API Security: A Complete Guide to Protecting APIs, Data and Access

APIs have become a fundamental part of modern digital infrastructure. They allow applications, cloud platforms, mobile apps, SaaS products and business systems to exchange data and trigger functions without requiring each system to understand how the other is built.

API adoption has accelerated as organizations move toward cloud services, microservices, distributed applications, third-party integrations and automated machine-to-machine communication. The same connectivity that makes APIs valuable, however, can also create security risks. An API can become a direct path to sensitive data or business functions when authentication is weak, authorization is incorrectly implemented, credentials are compromised or access permissions are excessive.

API security addresses these risks by protecting not only API endpoints, but also the data, applications and identities interacting through them.

This guide explains what API security is, how API security works, the main API security risks, OWASP guidance, testing approaches, security controls, governance considerations and practical best practices for building a stronger API security program.

What Is API Security?

API security is the practice of protecting application programming interfaces from unauthorized access, abuse, attacks, data exposure and misuse throughout their lifecycle.

API security combines controls for authentication, authorization, encryption, request validation, testing, threat monitoring, access governance and API lifecycle management. Its purpose is to ensure that only legitimate identities can interact with APIs, that they can perform only permitted actions, and that sensitive information and business functions remain appropriately protected.

This distinction matters because an API is not simply another webpage. APIs expose structured application functionality that can be called directly by users, applications, workloads and automated systems. Attackers can therefore manipulate API requests, credentials, object identifiers, parameters or workflows without necessarily interacting with the application’s normal user interface.

OWASP maintains a dedicated API Security Project to address security risks that are particularly relevant to APIs, including broken object-level authorization, broken authentication, security misconfiguration and improper API inventory management.

Effective API security management should therefore consider three questions continuously: Which APIs exist? Who or what can access them? And what are those identities allowed to do?

What Does API Security Protect?

API security protects the complete chain between an API request and the resource behind it.

This includes API endpoints that receive requests, the applications and services processing those requests, and the data being transmitted, retrieved or changed. It also protects the identities interacting with APIs, including employees, customers, applications, workloads, bots and service accounts.

Permissions are equally important. An authenticated identity should not automatically gain unrestricted access to every API function or data object.

Strong API security protection therefore connects endpoint security with identity, authorization, data protection and access governance so that legitimate connectivity does not become unnecessary exposure.

Why APIs Require Dedicated Security Controls

Traditional perimeter security is not sufficient for modern APIs because API communication routinely crosses network boundaries.

An API may be publicly accessible, called from a mobile app, consumed by a SaaS platform, connected to another cloud environment or used internally between microservices. In these architectures, being “inside” a trusted network does not necessarily mean a request should be trusted.

Organizations therefore need API-specific controls for discovery, authentication, authorization, request validation, testing and monitoring.

For a deeper implementation checklist, see [Internal Link: API Security Best Practices].

How Does API Security Work?

API security works as a layered security model rather than through one defensive technology.

Different controls answer different security questions. Authentication determines who or what is calling an API. Authorization decides whether that identity can perform a requested action. Encryption protects communications. Request validation checks whether submitted data is legitimate. Rate controls limit abuse, while logging and monitoring provide visibility into what happens after APIs are deployed.

A failure in one layer should not automatically result in unrestricted access to critical systems or information.

Authentication

API authentication verifies the identity making a request.

Depending on the architecture, organizations may use API keys, access tokens, OAuth 2.0, OpenID Connect, client certificates or other credential mechanisms.

The appropriate method depends on the identity involved and the sensitivity of the API. A user accessing personal information, for example, may require a different authentication model from a workload making automated system-to-system requests.

Authentication proves identity; it does not determine everything that identity should be allowed to access.

[Internal Link: API Authentication and Authorization]

Authorization

Authorization determines what an authenticated identity can access, which actions it can perform and what data it can retrieve or modify.

A legitimate user may be authorized to view their own record but not another person’s record. Similarly, a service account may require read access without needing administrative privileges.

Fine-grained authorization should therefore be enforced around objects, properties and functions. Applying least privilege further limits identities to only the access required for their legitimate purpose.

Encryption

APIs should use HTTPS with TLS to protect information while it is transmitted between clients, gateways and backend services.

Sensitive information should also receive appropriate protection when stored. Encryption reduces exposure from interception, but it does not replace authentication, authorization or other API security controls.

API Request Validation

APIs should validate incoming parameters, payloads, headers, data types and other inputs before processing them.

Validation helps prevent malformed or unexpected requests from reaching backend systems and reduces the risk of injection, manipulation and unauthorized data changes. APIs should accept only the input formats and values that the application genuinely requires.

Rate Limiting and Throttling

Rate limiting restricts how frequently API operations can be performed.

Appropriate limits can reduce brute-force attempts, automated abuse and resource exhaustion. Limits may need to account for identities, endpoints, operations and workload patterns rather than relying solely on an originating IP address.

OWASP identifies unrestricted resource consumption as a major API risk.

Logging and Monitoring

Logging and monitoring provide visibility into how APIs are being used.

Security teams should be able to investigate authentication failures, unusual request volumes, access to sensitive endpoints, unexpected identities and abnormal usage patterns. Monitoring complements preventive controls by identifying suspicious activity that may otherwise appear technically valid.

[Internal Link: API Security Monitoring]
[Internal Link: API Runtime Protection]

Why Is API Security Important?

APIs frequently connect directly to valuable business resources. A single interface may provide structured access to customer information, payment functions, internal records, administrative actions or connections between critical enterprise systems.

As organizations expose more APIs to the internet and distribute workloads across SaaS and cloud environments, the attack surface becomes harder to define using traditional network boundaries alone.

Machine-to-machine communication adds another layer of complexity. Applications, workloads, service accounts and automation may make API requests continuously without human involvement. If the credentials associated with one of those identities are compromised, malicious activity may resemble legitimate automated traffic.

Excessive permissions can amplify the impact. An attacker who compromises an identity with narrow privileges may reach only a limited set of resources. A compromised overprivileged identity can potentially reach much more.

Third-party integrations create additional dependencies because organizations may provide vendors or external applications with credentials and permissions to access internal API resources.

These factors make web API security both a technical and an access-management challenge. Protecting APIs requires organizations to understand not only malicious requests, but also legitimate identities that hold inappropriate or unnecessary permissions.

API Security and Identity Security

API security and identity security intersect through a simple chain:

Identity → Access → Permissions → API Resources → Data

Before an API request can be considered trustworthy, the organization needs confidence in the identity behind it and the permissions granted to that identity.

This applies to humans as well as service accounts, applications, bots, workloads and other machine identities.

Authentication establishes identity. Authorization determines permitted actions. Least privilege limits unnecessary access. Access governance helps determine whether those permissions remain appropriate over time.

SecurEnds supports periodic reviews for non-human identities, including service accounts, and provides visibility into entitlements, usage history and ownership to identify dormant or overprivileged identities.

[Internal Link: Non-Human Identity Management]

What Are the Common API Security Risks?

API security vulnerabilities can originate in design, authentication, authorization, data handling, configuration and lifecycle management.

Rather than treating every issue as an isolated vulnerability, organizations can group API security risks according to where security controls fail.

Authentication and Authorization Risks

Broken authentication can allow an attacker to impersonate a legitimate identity or misuse an authentication mechanism.

Broken authorization occurs when an API authenticates an identity correctly but fails to enforce what that identity is permitted to access. Excessive permissions create another risk by allowing legitimate users or machine identities to reach more resources than their roles require.

Authorization failures are particularly significant in APIs because object, property and function access can often be manipulated directly through requests.

Data and Credential Risks

API keys, tokens and secrets may be exposed through source code, repositories, configuration files, logs or insecure client implementations.

Once stolen, those credentials can provide attackers with seemingly legitimate API access.

APIs can also expose sensitive information by returning fields a caller does not need. Security teams should therefore consider both direct sensitive-data exposure and excessive data exposure, where a legitimate API response contains unnecessarily broad information.

API Configuration and Application Risks

Poor request validation can create opportunities for injection or other backend attacks.

Security misconfiguration can expose unnecessary functionality, verbose errors, weak headers or insecure defaults. Weak rate controls may allow attackers to automate credential attacks, scraping, enumeration or resource-intensive operations at scale.

Together, these weaknesses show why secure API development needs to address both code-level vulnerabilities and operational controls.

API Visibility and Lifecycle Risks

Security teams cannot protect APIs they do not know exist.

Shadow APIs, undocumented endpoints, rogue APIs and abandoned versions can remain outside normal security processes. Deprecated APIs are particularly risky when newer versions receive security improvements while the older endpoint remains reachable.

Maintaining an accurate API inventory is therefore a foundational security control, not merely an asset-management exercise.

[Internal Link: API Discovery]

Third-Party API Risks

Organizations often consume data and functions from external APIs.

If a third-party service is compromised, misconfigured or returns unexpected information, the consuming application can inherit additional risk. External API responses should therefore be validated rather than automatically trusted.

[Internal Link: API Threat Detection]
[Internal Link: API Vulnerability Scanning]

OWASP API Security Top 10 Explained

The OWASP API Security Top 10 is an awareness framework designed to help developers, architects, security professionals and organizations understand important API security weaknesses.

The current published API Security Top 10 is the 2023 edition, which contains ten major risk categories. OWASP explains that the project’s goal is to educate people involved in API development and maintenance about common API security weaknesses and ways to address them.

Broken Object Level Authorization

Broken Object Level Authorization, or BOLA, occurs when an API exposes an object identifier but does not adequately verify whether the requesting identity is authorized to access that specific object.

Attackers may manipulate identifiers in URLs, parameters, headers or payloads to access another user’s resources.

Broken Authentication

Broken Authentication occurs when weaknesses in authentication mechanisms allow attackers to impersonate legitimate users or compromise API sessions.

Weak credential protection, token-handling flaws and authentication flows vulnerable to automated attacks can all contribute to this risk.

Broken Object Property Level Authorization

An identity may legitimately access an object while still being unauthorized to view or modify every property within it.

This category addresses inadequate property-level authorization that can result in unauthorized data exposure or modification.

Unrestricted Resource Consumption

API calls consume network, compute, memory, storage and other resources.

Without suitable controls, attackers can generate expensive or high-volume requests that affect service availability, increase operational costs or facilitate brute-force and automated abuse.

Broken Function Level Authorization

Some API operations should be available only to specific roles or identities.

Broken function-level authorization occurs when an API fails to restrict privileged functions appropriately, allowing ordinary users to invoke administrative or sensitive operations.

Unrestricted Access to Sensitive Business Flows

Attackers may abuse legitimate business functionality through automation.

A technically valid API operation can still create risk when attackers repeatedly execute sensitive processes such as registrations, purchases, bookings or transactions at unintended scale.

Server-Side Request Forgery

Server-Side Request Forgery, or SSRF, can occur when an API retrieves a remote resource using a destination influenced by user-supplied input.

Attackers may attempt to make the server connect to internal, restricted or otherwise unintended resources.

Security Misconfiguration

Security misconfiguration can include insecure defaults, unnecessary features, missing protections, overly detailed errors or inconsistent API configurations.

Configuration requirements should be defined and maintained across development, testing, cloud and production environments.

Improper Inventory Management

Organizations may operate multiple API versions, environments and hosts.

Without an accurate inventory, deprecated, undocumented or forgotten endpoints can remain exposed and may not receive the same testing, monitoring and controls as known production APIs.

Unsafe Consumption of APIs

Applications frequently consume data from external APIs.

OWASP warns against placing greater trust in information received from third-party APIs than in other user-controlled input. Responses should therefore be validated and processed using appropriate security controls.

The OWASP list demonstrates why no single product or control can solve API security. Organizations need continuous API discovery, secure authentication, granular authorization, testing, inventory management, request validation and monitoring working together.

For a deeper breakdown of each category and mitigation approach, see [Internal Link: OWASP API Security].

Authentication vs Authorization in API Security

Authentication and authorization are closely related, but they solve different security problems.

Authentication	Authorization
Who are you?	What can you access?
Verifies identity	Determines permissions
Establishes the caller’s identity	Controls permitted resources and actions
Typically occurs before protected access	Applies after identity has been established

Consider an employee using an API-enabled HR application.

Authentication may confirm that the employee is who they claim to be. Authorization then determines whether that employee can access only their own information, information belonging to their team or administrative records across the organization.

The same distinction applies to machine identities.

A service account can possess a valid certificate or token and therefore authenticate successfully. That does not mean it should have access to every API endpoint or administrative function.

This is why authorization deserves the same attention as authentication in API security. Several OWASP API Security Top 10 categories specifically address failures in object-, property- and function-level authorization.

Why Least Privilege Matters for APIs

Least privilege limits users and machine identities to only the access needed for their legitimate responsibilities.

A reporting workload that only retrieves information should not automatically have write or delete permissions. An integration created for one application should not receive broad administrative access simply because it is simpler to configure.

Applying least privilege reduces the potential impact of compromised credentials and limits unnecessary pathways to sensitive information.

The principle must also be maintained over time because roles, integrations, applications and responsibilities change.

Why Access Reviews Matter for API Permissions

Permissions that were appropriate when initially granted can become stale or excessive.

Periodic reviews help organizations examine user access, application permissions, service accounts, privileged access and entitlements to determine whether each remains justified.

SecurEnds user access reviews are designed to collect access information, support reviewer attestation, identify inappropriate or outdated permissions and facilitate remediation. Its non-human identity capabilities extend periodic access reviews to service accounts and other machine identities.

This supports least privilege as an ongoing governance process rather than a one-time configuration decision.

[Internal Link: SecurEnds User Access Reviews]
[Internal Link: API Authentication and Authorization]

API Security Across the API Lifecycle

Effective API security begins before an endpoint is publicly deployed and continues until the API is completely retired.

API Design

Security requirements should be established alongside API functionality.

Teams should define authentication, authorization, expected identities, sensitive data exposure, permitted operations and potential misuse scenarios before implementation begins.

API Development

Developers should implement secure input handling, appropriate authorization checks, secrets management and safe dependency practices.

Security decisions should be enforced server-side rather than relying on what the application interface allows users to see.

API Testing

Testing should evaluate authentication, authorization, object access, input processing, configuration and business logic.

Direct API testing is essential because attackers are not limited to requests generated by the normal user interface.

API Deployment

Production deployments should enforce secure configurations, encryption, authentication policies, traffic controls and appropriate API gateway or runtime protections.

Credentials and secrets should be managed securely rather than embedded in code.

API Monitoring

After deployment, organizations need visibility into API behavior.

Monitoring should help identify unusual usage volumes, authentication failures, unexpected endpoints, suspicious identities and deviations from normal API activity.

API Retirement

Retiring an API means more than removing it from documentation.

Organizations should disable obsolete endpoints, revoke credentials, remove unnecessary permissions and confirm that deprecated versions can no longer be accessed.

API security must therefore be continuous across design, development, deployment, runtime and retirement, rather than treated as a one-time penetration test before release.

API Security for REST, SOAP and GraphQL APIs

The fundamentals of API security remain consistent across different architectures, but implementation risks can vary.

REST API Security

REST API security commonly includes HTTPS, token-based authentication, OAuth where appropriate, object-level authorization, input validation, rate controls and monitoring.

Because REST APIs expose predictable HTTP operations and resource-oriented endpoints, authorization must be enforced independently for every relevant object and function rather than relying on the frontend application to limit access.

SOAP API Security

SOAP APIs commonly exchange structured XML messages and may use controls such as WS-Security for message-level protection.

Organizations should consider transport security, authentication, authorization, XML parsing and message integrity. Complex XML processing and legacy implementations can also create security considerations that differ from modern REST environments.

GraphQL API Security

GraphQL allows clients to specify exactly which fields and relationships they want returned, creating significant flexibility but requiring careful security controls.

Teams should account for query depth, query complexity, excessive requests, field-level authorization, schema exposure and rate limiting.

GraphQL batching can also complicate conventional request-based limits. OWASP provides an example in which multiple authentication attempts are bundled into a GraphQL request to bypass simple rate-limiting approaches.

The goal is not to restrict GraphQL’s flexibility unnecessarily, but to apply authorization and resource controls at the level where the API actually processes requests.

API Security for Cloud and SaaS Environments

Cloud and SaaS adoption makes API environments more distributed.

A single business process may involve a SaaS application, cloud workload, identity provider, API gateway, data platform and third-party service. Each connection can introduce another API, identity and set of permissions that must be understood.

As environments become more distributed, organizations need consistent visibility across APIs rather than assuming each platform can be secured in isolation.

API Security in Multi-Cloud Environments

Multi-cloud environments can introduce different identity models, API gateways, policy frameworks and logging systems across cloud providers.

Security teams must maintain consistent authentication, authorization and monitoring expectations even when implementation varies.

Centralized visibility into identities and entitlements can help organizations understand access that spans multiple cloud and SaaS systems.

API Security for Third-Party Integrations

Third-party integrations often receive tokens or application permissions that provide ongoing API access.

Organizations should know who owns each integration, what resources it can access, how its credentials are protected and how access will be removed when the relationship changes.

Permissions should be scoped to the specific integration requirement rather than granted broadly for convenience.

External API responses should also be validated before trusted application processing occurs.

Machine Identities and Service Accounts

Much of today’s API traffic does not originate directly from human users.

Applications, workloads, bots, automation platforms, AI agents and service accounts may all authenticate to APIs independently. These non-human identities can accumulate privileges, persist beyond their original purpose or lose clear ownership.

SecurEnds provides a centralized inventory for service accounts and non-human identities, supports ownership tracking and enables periodic access reviews using entitlement, usage and login information.

Machine identity governance helps organizations answer a critical API security question: not just whether a credential is valid, but whether the identity behind it should still possess the associated access.

[Internal Link: Non-Human Identity Management]

What Is Zero Trust API Security?

Zero Trust API security applies Zero Trust principles to API interactions by requiring requests to be explicitly authenticated, authorized and evaluated rather than trusted automatically because they originate from an internal network or previously trusted environment.

NIST describes Zero Trust as an approach that moves security away from static network perimeters and toward users, assets and resources. It also emphasizes eliminating implicit trust based solely on network location or ownership.

For API environments, Zero Trust principles can include:

• Verifying identities making requests
• Authenticating human and machine identities
• Authorizing each relevant resource and action
• Applying least privilege
• Protecting communication
• Monitoring activity continuously
• Reducing opportunities for lateral movement

Zero Trust does not mean repeatedly challenging every user without context. It means that trust is not granted automatically simply because traffic appears to originate from a familiar location.

Identity as the Foundation of Zero Trust API Security

Zero Trust API security can be understood through another chain:

Identity → Authentication → Authorization → Least Privilege → Monitoring

First, the organization establishes who or what is making a request. It then verifies that identity and determines which resources and operations are permitted.

Least privilege limits the consequences of compromise, while ongoing monitoring looks for behavior that may indicate credentials or access are being misused.

Identity therefore becomes a critical control point for both human and machine API access.

What Is API Security Testing?

API security testing evaluates APIs for weaknesses in authentication, authorization, request processing, configuration and business logic before those weaknesses can be exploited.

Testing an API directly is important because attackers can construct requests that the normal web or mobile interface would never generate.

A mature testing program combines different approaches rather than expecting a single scanner to discover every API security vulnerability.

API Penetration Testing

API penetration testing simulates attacker behavior against API endpoints.

Testing may investigate authorization bypass, business-logic abuse, authentication weaknesses, object manipulation, insecure configuration and other paths through which an attacker could reach protected resources.

Authentication Testing

Authentication testing evaluates how securely APIs establish identity.

It can assess credential handling, token validation, session behavior, login flows, token expiry and whether authentication mechanisms can be bypassed or abused.

Authorization Testing

Authorization testing verifies that authenticated identities cannot access objects, properties or functions outside their permissions.

Testing should evaluate both horizontal access between equivalent users and vertical access to privileged functions.

Input Validation Testing

Input validation testing sends malformed, unexpected or manipulated values to API parameters, headers and payloads.

The objective is to determine whether untrusted information can reach sensitive backend processing or produce unintended application behavior.

Vulnerability Scanning

Automated vulnerability scanning can identify known weaknesses and security misconfigurations across large API environments.

Scanning adds scale but should complement, rather than replace, authorization testing and business-logic analysis.

Continuous API Security Testing

API environments change as code, schemas, dependencies, permissions and infrastructure evolve.

Security testing should therefore be integrated throughout development and deployment, with production monitoring providing additional visibility once APIs are live.

For deeper testing methodologies, see [Internal Link: API Security Testing].

API Security Tools and Technologies

API security usually requires several categories of technology because different controls address different parts of the risk.

API Gateways

API gateways centralize traffic between clients and backend services.

They can enforce authentication, traffic policies, routing and rate limits, but gateway controls do not automatically eliminate vulnerabilities in API code or business authorization.

Web Application Firewalls

A web application firewall can detect and block certain malicious HTTP traffic patterns.

WAF protection remains useful, but API security also requires endpoint context, identity awareness, authorization testing and visibility into machine-driven API activity.

API Discovery Tools

API discovery tools identify known and previously unmanaged endpoints.

They help security teams build inventories, identify deprecated or shadow APIs and reduce the visibility gap associated with improper API inventory management.

API Security Testing Tools

Testing tools evaluate APIs for vulnerabilities, incorrect configurations and insecure behavior.

Different technologies may support automated scanning, fuzzing, specification testing or specialized authentication and authorization analysis.

IAM and Identity Governance

IAM establishes and manages identity access, while Identity Governance and Administration (IGA) adds oversight around whether access is appropriate.

Identity governance helps organizations review entitlements, enforce access policies, certify permissions and remove access that no longer has a valid business purpose.

SecurEnds provides user access reviews and governance capabilities across human and non-human identities.

SIEM and Security Monitoring

SIEM and monitoring technologies aggregate security events and API telemetry to help teams detect suspicious behavior, investigate incidents and correlate API activity with events occurring across other systems.

Secrets Management

Secrets-management technologies protect credentials such as API keys, tokens, passwords and certificates.

Strong processes should also address secret creation, storage, rotation, ownership and revocation.

API Security vs Web Application Security

API security and web application security overlap, but they address different interaction models.

A traditional web application primarily presents an interface to a human user. An API exposes programmatic endpoints that can be called by users, mobile applications, workloads, partners and automated systems.

This creates differences in several areas.

Attack surface: APIs may expose many individual objects and business functions directly.

Authentication: API environments rely heavily on tokens, keys, OAuth and machine credentials in addition to human authentication.

Data exposure: APIs commonly return structured information that can be programmatically extracted at scale.

Machine identities: Automated workloads can interact without a human session.

Access patterns: High-volume API traffic may be legitimate, making behavioral context important.

Testing: API testing frequently requires manipulating requests directly rather than relying on a browser interface.

OWASP maintains separate projects for web application and API security risks, reflecting these distinctions.

Organizations generally need both disciplines. Web application security protects the application experience, while API security addresses the programmatic interfaces and resources supporting it.

API Security vs API Management

API management and API security also serve different purposes.

API management typically focuses on:

• Publishing APIs
• Managing versions and lifecycle
• Routing and controlling traffic
• Usage analytics
• Developer onboarding and experience

API security focuses on:

• Protecting API endpoints
• Authenticating identities
• Enforcing authorization
• Preventing abuse and attacks
• Monitoring suspicious activity
• Managing API-related risk
• Governing access

The disciplines overlap because API management platforms and gateways may provide security functions such as authentication or rate limiting.

However, deploying an API gateway does not automatically provide complete API security protection. It cannot by itself guarantee that every object-level authorization rule is correct, that unknown APIs have been discovered, that service-account permissions remain appropriate or that application business logic cannot be abused.

Organizations therefore need to view API management as one part of the operating environment rather than a substitute for a comprehensive API security program.

API Security Best Practices

Strong API security controls should reduce risk throughout the API lifecycle while keeping protection practical for development, security and identity teams.

Maintain a Complete API Inventory

Discover and document public, internal, partner, development and legacy APIs.

Track ownership, environment, version, data sensitivity and lifecycle status so unmanaged endpoints do not remain outside security processes.

Use Strong Authentication

Choose authentication mechanisms according to API sensitivity and caller type.

Protect tokens, credentials and certificates carefully, and avoid depending on weak or long-lived credentials when stronger alternatives are appropriate.

Enforce Fine-Grained Authorization

Apply authorization to objects, properties and functions.

Never assume that successful authentication or access to one resource means an identity should automatically reach related data or administrative operations.

Apply Least Privilege

Users, workloads and service accounts should receive only the permissions needed for their current responsibilities.

Restrict scopes and privileged operations instead of granting broad access for implementation convenience.

Regularly Review API Access

Periodically review user, application and machine permissions.

Look for role changes, unnecessary entitlements, dormant accounts, orphaned service identities and privileged access that no longer has a business justification.

Secure API Keys, Tokens and Secrets

Keep secrets out of public repositories and exposed client-side code.

Establish secure storage, rotation, ownership and revocation processes so compromised or obsolete credentials can be contained quickly.

Encrypt API Traffic

Use HTTPS with TLS to protect API communication in transit.

Apply appropriate data-protection controls to sensitive information stored by applications and supporting infrastructure.

Apply Rate Limits

Define rate and resource limits according to legitimate usage patterns.

Protect authentication endpoints, expensive operations and sensitive business workflows from high-volume automated abuse.

Validate Inputs

Validate parameters, headers, payloads, data types and expected formats.

Treat data received from users and third-party APIs as untrusted until it has been appropriately checked.

Monitor API Activity

Monitor API usage for suspicious authentication behavior, unusual traffic volumes, unexpected endpoints, sensitive operations and abnormal identities.

Combine logs with security context so activity can be investigated effectively.

Govern Machine Identities

Maintain ownership and visibility for service accounts, workloads, API credentials, bots and automation.

Review whether their entitlements remain necessary instead of allowing non-human access to persist indefinitely.

Test APIs Continuously

Integrate security testing throughout development and deployment.

Combine automated scanning with authorization, business-logic and runtime analysis rather than relying on a one-time pre-release assessment.

Retire Deprecated APIs

Disable obsolete endpoints, revoke associated credentials and remove outdated permissions.

Verify retirement technically instead of simply removing the old API from documentation.

For an expanded implementation framework, see [Internal Link: API Security Best Practices].

API Security Governance and Compliance

API security is not only a technical engineering concern. Organizations also need policies, ownership, review processes and evidence showing that security controls are operating as intended.

Governance connects technical API controls with broader cybersecurity and compliance responsibilities.

API Security Standards and Frameworks

Organizations can use established frameworks to inform their API controls.

OWASP API Security Top 10 provides an API-specific risk framework. NIST guidance supports principles around Zero Trust, identity and cloud-native access control. ISO/IEC 27001 provides a broader information-security management framework, while PCI DSS establishes security requirements relevant to organizations handling payment-card data.

The appropriate framework depends on the organization’s systems, regulatory obligations and risk profile.

The frameworks should guide security decisions rather than become checklist exercises disconnected from actual API risk.

[Internal Link: API Security Standards]

API Access Governance

API access governance determines how permissions are requested, approved, reviewed and removed.

Organizations should define policies covering entitlements, privileged access, service identities and application access.

Least privilege establishes the access objective; periodic access reviews help verify whether real permissions continue to meet that objective.

When unnecessary or inappropriate access is identified, governance processes should include remediation rather than stopping at visibility.

SecurEnds supports access reviews, attestation and remediation workflows designed to help organizations identify excessive or outdated permissions.

API Security Compliance

Compliance requires organizations to demonstrate that relevant security controls are not merely documented but consistently applied.

Evidence may need to show how APIs are authenticated, how authorization is controlled, how sensitive information is protected, how activity is monitored and how identity access is reviewed.

API security compliance should therefore connect technical controls with risk management, access governance, policy enforcement and audit evidence.

The specific controls required depend on the organization’s applicable regulations and standards, so API security programs should map technical practices to the requirements that genuinely apply.

[Internal Link: API Security Compliance]

How Identity Governance Strengthens API Security

API gateways, runtime controls and security testing help protect API endpoints. But another question remains:

Should the identity making a legitimate request have that access in the first place?

This is where identity governance strengthens API security.

Discover Who Has Access

Security teams need visibility into human and machine identities before access risk can be evaluated.

A consolidated view of users, applications, service accounts and their entitlements helps reveal who can reach sensitive systems and resources.

Identify Excessive Permissions

Permissions can expand as employees change roles, applications evolve and integrations accumulate new capabilities.

Identity governance helps identify accounts with access broader than their legitimate responsibilities require.

Review and Certify Access

Access reviews allow managers, application owners and entitlement owners to confirm whether existing access remains justified.

SecurEnds supports both user access reviews and recurring reviews for non-human identities such as service accounts.

Remove Unnecessary Access

Visibility alone does not reduce risk.

When reviews identify obsolete, excessive or inappropriate permissions, organizations need a process for revocation or adjustment so the actual access environment moves closer to least privilege.

Govern Privileged Access

Administrative and highly sensitive permissions deserve greater scrutiny because compromise can have a disproportionate impact.

Governance helps organizations identify privileged entitlements and establish accountability around their continued use.

Improve Visibility Across Applications

API-related identities often interact with multiple SaaS, cloud and enterprise applications.

Centralized governance can reveal access relationships that are difficult to understand when every application is evaluated separately.

Support Least-Privilege Policies

Least privilege changes as business requirements change.

Recurring certification and remediation provide a mechanism for keeping permissions aligned with current responsibilities instead of allowing access to accumulate indefinitely.

The central principle is straightforward:

API security is not only about securing the endpoint. It is also about governing the identities and permissions that can reach the endpoint.

How SecurEnds Supports Identity-Centric API Security

SecurEnds combines identity-governance capabilities with dedicated API security functionality.

From the identity perspective, SecurEnds supports user access reviews, entitlement visibility, access certification, remediation workflows and governance for non-human identities such as service accounts. Its non-human identity capabilities include centralized inventory, ownership tracking and recurring access reviews using entitlement and usage information.

SecurEnds also currently provides dedicated API Security capabilities including API inventory and discovery, threat detection, schema and specification validation, identification of authentication and authorization vulnerabilities, and API-to-API adaptive MFA.

Its API discovery offering describes scanning traffic, code, gateways and ingress to build an API inventory, classify endpoints and understand risk posture.

These capabilities address different layers of API security rather than treating identity governance, endpoint visibility and runtime security as interchangeable controls.

[Internal Link: SecurEnds API Security]
[Internal Link: SecurEnds User Access Reviews]
[Internal Link: SecurEnds Non-Human Identity Management]

Building an Effective API Security Strategy

A practical API security strategy should move from visibility to control and then to continuous verification.

Step 1: Discover Your APIs

Identify APIs operating across public, private, cloud, SaaS, development and partner environments, including endpoints that may not appear in existing documentation.

Step 2: Inventory API Assets

Record API ownership, versions, environments, business purpose, data sensitivity and lifecycle status.

An inventory should help teams distinguish active production APIs from test, shadow and deprecated endpoints.

Step 3: Identify Human and Machine Identities

Determine which employees, customers, applications, service accounts, workloads, bots and external integrations interact with each API.

Establish ownership for non-human identities where possible.

Step 4: Map API Permissions and Data Access

Understand which identities can read, modify, create, delete or administer API resources.

Map those permissions to the sensitive data and business functions they expose.

Step 5: Prioritize High-Risk APIs

Prioritize protection according to exposure, business criticality, sensitive data, privileged functionality, known vulnerabilities and the identities permitted to interact with the API.

Step 6: Strengthen Authentication and Authorization

Use appropriate authentication mechanisms and verify authorization at object, property and function levels.

Do not treat a valid credential as proof that every requested action should be allowed.

Step 7: Apply Least Privilege

Reduce permissions to what users and machine identities actually require.

Pay particular attention to privileged integrations, old service accounts and credentials with broad scopes.

Step 8: Test and Monitor APIs

Combine development-stage security testing with production monitoring and runtime protection.

Testing finds weaknesses before exploitation; monitoring helps identify suspicious behavior after deployment.

Step 9: Review and Remediate Access

Periodically reassess API-related permissions and remove stale, excessive or inappropriate access.

Repeat the process as APIs, identities and business requirements change.

Protect APIs, Data and the Identities That Connect Them

API security requires more than protecting a URL from malicious traffic.

A complete approach connects API endpoints + data + identities + permissions + monitoring + governance.

Organizations need visibility into which APIs exist, strong authentication and granular authorization, secure data handling, continuous testing and monitoring, and governance processes that prevent human and machine identities from retaining unnecessary access.

OWASP’s API Security Top 10 reinforces how closely API risk is tied to authorization, authentication, resource controls and inventory management.

SecurEnds supports this broader security model through API security capabilities alongside access reviews, entitlement governance and non-human identity management.

Explore how SecurEnds can help improve visibility and control across APIs and the identities accessing critical enterprise resources.

[Internal Link: SecurEnds API Security]

Frequently Asked Questions

What is API security?

API security is the practice of protecting APIs from unauthorized access, misuse, attacks and unintended data exposure.

It includes controls for API discovery, authentication, authorization, encryption, request validation, monitoring, testing and access governance. Strong API security protects endpoints as well as the applications, data and human or machine identities interacting through them.

Why is API security important?

API security is important because APIs often provide direct access to sensitive data and business functionality.

Compromised credentials, broken authorization, excessive permissions, unmanaged endpoints or insecure integrations can give attackers pathways into critical resources. Modern cloud, SaaS and machine-to-machine environments also increase the number of APIs and identities organizations need to protect.

What are the biggest API security risks?

Major API security threats include broken authentication, broken object- and function-level authorization, excessive permissions, exposed API keys, token theft, sensitive-data exposure, resource abuse, security misconfiguration, shadow APIs and unsafe third-party API consumption.

OWASP’s API Security Top 10 provides a widely used framework for understanding several of these risks.

What is the OWASP API Security Top 10?

The OWASP API Security Top 10 is an awareness framework covering important security risks specific to APIs.

The 2023 edition includes Broken Object Level Authorization, Broken Authentication, Broken Object Property Level Authorization, Unrestricted Resource Consumption, Broken Function Level Authorization, Sensitive Business Flow abuse, SSRF, Security Misconfiguration, Improper Inventory Management and Unsafe Consumption of APIs.

What is the difference between API authentication and authorization?

Authentication verifies who or what is making an API request.

Authorization determines what that authenticated identity is allowed to access or do.

An identity can authenticate successfully and still be unauthorized to access a particular record, property or administrative function. Both controls are therefore essential to secure APIs effectively.

How does Zero Trust improve API security?

Zero Trust removes the assumption that an API request should be trusted simply because it originates from an internal or familiar environment.

Instead, identities are authenticated, access is explicitly authorized, least privilege is applied and activity is monitored continuously. NIST describes Zero Trust as shifting security away from static perimeter assumptions toward users, assets and resources.

What is API security testing?

API security testing evaluates endpoints for vulnerabilities in authentication, authorization, data handling, configuration, request processing and business logic.

Common approaches include penetration testing, authorization testing, input validation, vulnerability scanning and continuous security testing throughout development and deployment.

[Internal Link: API Security Testing]

How does identity governance help secure APIs?

Identity governance helps organizations understand which human and non-human identities possess access, whether their permissions remain appropriate and whether unnecessary entitlements should be removed.

Access reviews, certification, remediation and machine-identity governance complement technical API controls by reducing excessive and stale permissions.