APIs are the backbone of how modern applications, services, and even AI-powered systems work.
However, that also makes them a prime target for attackers. In 2024 alone, there were 311 billion web attacks, and a significant portion of that traffic was aimed at APIs. In the first half of 2025, organizations across every industry report rising API abuse, misconfiguration exploits, and automated attacks that slip past traditional security tools.
Still, the challenge is not just how many attacks are happening, but how quickly and quietly they evolve. And the truth is: there is no single tool that can protect you. API security only works when it’s built on layered, well-defined best practices supported by industry guidance like the OWASP API Security Top 10.
As organizations scale and adopt AI systems that communicate through APIs, the attack surface is expanding faster than traditional protections can keep up. That’s why API security can’t be treated like a checklist you revisit once in a while, it has to be built into how you design, build, and maintain your APIs from day one.
In this article, you’ll find the top 10 API security best practices for 2026, a clear, actionable, and up-to-date framework for securing your APIs against today’s most common and costly threats.
The top 10 API security best practices at a glance:
- Enforce strong authentication and authorization
- Use encryption everywhere (in transit and at rest)
- Validate and sanitize all inputs
- Maintain a complete, continuously updated API inventory
- Implement Rate Limiting and Throttling
- Adopt secure-by-design API development practices
- Scan your APIs continuously
- Harden error handling and logging
- Integrate security testing into CI/CD
- Monitor APIs in production for anomalies and misuse
See below for in-depth coverage.
TL;DR
Aikido Security gives your team complete, automated API protection that traditional DAST, manual pentests, and basic OWASP checklists can’t match. Instead of relying on outdated specs or manual sample data, Aikido auto-discovers every endpoint, including shadow and undocumented APIs and generates realistic traffic to test them with deep, contextual scanning.
Its AI-driven fuzzing and push-request engine mimic real-world attacks across REST and GraphQL, uncovering broken authentication, injection flaws, misconfigurations, and other OWASP API Top 10 risks long before they hit production.
With Autofix and ready-to-merge PRs, teams can remediate issues in seconds, not days, turning API security from a slow, specialized process into something developers can act on instantly.
What is API Security?
API security is the practice of protecting application programming interfaces from misuse, data exposure, and unauthorized access. It focuses on securing the way systems communicate with each other, ensuring that only the right users, services, and applications can interact with your APIs. Because APIs often handle sensitive data and power critical workflows, even a small gap, like weak authentication or overly permissive endpoints, can lead to serious breaches.
API security also covers the processes, tools, and controls used to detect vulnerabilities before attackers can exploit them. This includes validating every request, enforcing least-privilege access, encrypting data, spotting abnormal behavior, and monitoring your entire API surface. As modern applications become more interconnected and API-driven, strong API security becomes essential for preventing attacks and maintaining trust.
Common API Security Vulnerabilities
APIs face a variety of threats, some overlapping with traditional web app issues and some unique to the API paradigm. Understanding these common vulnerabilities is the first step to defending against them. Many of these risks are captured in the OWASP Top 10, which as earlier stated, serves as a checklist for the most prevalent API weaknesses.
Here are the major API security vulnerabilities you should know:
- Broken Authentication & Authorization: These are the most frequent API weaknesses. Broken authentication occurs when identity verification mechanisms like tokens or API keys, are implemented incorrectly or are easily bypassed. Broken authorization refers to APIs not properly enforcing what users are allowed to do or access. For example, an attacker could fetch another user’s data by simply changing an ID in the request (a common Broken Object Level Authorization, or BOLA).
- Excessive Data Exposure: Many APIs return more data than necessary, leaving sensitive information exposed. Attackers can directly query these endpoints to access internal IDs, personal info, or other data not meant for external consumption. Using proper response schemas and validation can reduce this risk.
- Lack of Resource Limiting: Without rate limits or quotas, APIs can be abused for denial-of-service attacks or excessive resource consumption. Attackers may flood endpoints with requests or send complex queries that overwhelm your servers. Implementing throttling and payload size checks helps mitigate this.
- Injection Flaws: APIs are vulnerable to SQL, NoSQL, command, and cross-site scripting (XSS) injections if user input isn’t validated. For instance, an API that inserts unsanitized filters into database queries could allow attackers to execute arbitrary commands, potentially leaking or corrupting data. Strong input validation and parameterized queries are essential defenses.
- Security Misconfiguration: Misconfigured endpoints, verbose error messages, open CORS settings, default credentials, or directory listings create easy targets. Regular configuration reviews and secure defaults are crucial to avoid these pitfalls.
- Improper Assets Inventory & Version Management: Organizations with numerous APIs often lack up-to-date records of endpoints and versions, creating “zombie” or shadow APIs. Outdated or forgotten APIs can harbor known vulnerabilities. Maintaining a full API inventory and versioning strategy is critical.
- Insufficient Logging & Monitoring: Many breaches go unnoticed because unusual API behavior isn’t logged or monitored. Without proper alerts, attackers can operate undetected. Comprehensive logging and active monitoring help catch attacks early.
- Server-Side Request Forgery (SSRF): SSRF occurs when APIs fetch external resources based on unvalidated user input, potentially exposing internal systems. Whitelisting allowed domains and validating outbound requests can mitigate SSRF risks.
- Business Logic Vulnerabilities: These flaws exploit intended API functionality rather than code bugs. For example, repeated use of a discount API or exploiting a money-transfer workflow can lead to fraud. Thorough threat modeling and custom checks are needed to prevent logic abuse.
- Third-Party API Risks: Integrating external APIs without validation can introduce vulnerabilities. Attackers may manipulate third-party data to compromise your system. Always treat external API inputs as untrusted and handle errors safely.
Many API vulnerabilities compound. For example, a misconfiguration may enable broken authentication, which then allows excessive data exposure. Using the OWASP API Security Top 10 as a guide helps teams identify, prioritize, and mitigate these risks before attackers do.
Top 10 API Security Best Practices
APIs are the backbone of modern digital business, powering apps, integrations, and ecosystems. With this importance comes increased risk, APIs are now among the top targets for attackers. Securing them effectively requires a multi-layered, proactive approach that combines design, testing, monitoring, and automation.
1. Enforce Strong Authentication and Authorization
This is the bedrock of API security. If you can't verify who is making a request and what they're allowed to do, nothing else matters.
- Authentication (The "Who"): Always verify the identity of the user or service calling your API. Don't leave any endpoints open unless they are explicitly public and serve non-sensitive data.
- Standards to Use: Use robust, industry-standard protocols like OAuth 2.0 and OpenID Connect (OIDC) for user-facing applications. For service-to-service communication, use API keys with strong, randomly generated values or implement mutual TLS (mTLS) for a higher level of trust.
- Authorization (The "What"): Once a user is authenticated, you must enforce what they are permitted to access. This is where the most common and dangerous API vulnerabilities, like Broken Object Level Authorization (BOLA), occur.
Best Practices:
- Authentication: Use OAuth 2.0 and OpenID Connect (OIDC) for user-facing APIs. For service-to-service communication, implement API keys or mutual TLS (mTLS).
- Authorization: Enforce permission checks on every request. Avoid trusting client-side restrictions. For example, /users/{id}/profile should only be accessible to the correct user.
- Extra Tip: Consider token expiration, revocation, and scope limitations to further reduce exposure.
2. Use Encryption Everywhere
Unencrypted data is an open book for anyone listening in. Encrypting data both in transit and at rest is non-negotiable.
Best Practices:
- Data in Transit: All API traffic must use HTTPS with TLS 1.2 or higher. This prevents man-in-the-middle attacks where an attacker could intercept, read, or modify API requests and responses. For up-to-date recommendations, see the Mozilla TLS/SSL Configuration Best Practices.
- Data at Rest: Sensitive data stored in databases or file systems should also be encrypted. This provides a crucial layer of defense if an attacker manages to breach your infrastructure.
3. Validate and Sanitize All Inputs
Treat all data coming from a client as untrusted. Rigorous input validation is your primary defense against a wide range of attacks, especially injection flaws. For in-depth guidance, review the OWASP guide to input validation and injection prevention.
Best Practices:
- Schema Validation: Define a strict schema for your API requests and responses using a format like the OpenAPI Specification. Your API gateway or application logic should reject any request that doesn't conform to this schema (e.g., wrong data types, unexpected properties, incorrect format).
- Content Validation: Sanitize inputs to prevent injection attacks (SQLi, NoSQLi, Command Injection). Use parameterized queries or prepared statements instead of manually constructing query strings.
- Payload Size Limiting: Enforce reasonable size limits on request bodies, headers, and URL parameters to prevent resource exhaustion and denial-of-service attacks.
4. Maintain a Complete, Continuously Updated API inventory
You can't protect what you don't know you have. As organizations scale, it's easy to lose track of all the APIs being deployed, leading to "shadow" (undocumented) and "zombie" (outdated but still active) APIs, as stated previously above.
Best Practices:
- Discovery: Use an API discovery tool to automatically scan your environment and identify all API endpoints. These tools can analyze network traffic or connect to your repositories to create a complete inventory.
- Documentation: Maintain up-to-date documentation for every API, including its owner, purpose, data sensitivity level, and version. This is essential for both security reviews and incident response.
Aikido’s platform simplifies this by automatically discovering your APIs from your source code and running applications, giving you a single source of truth for your entire API attack surface. You can get a complete view of your API landscape by trying Aikido.
5. Implement Rate Limiting and Throttling
Attackers often rely on automation to abuse APIs, whether for brute-forcing credentials, scraping data, or launching denial-of-service attacks.
Best Practices:
- Rate Limiting: Set limits on how many requests a user or IP address can make within a certain time frame (e.g., 100 requests per minute).
- Throttling: Slow down responses for clients who exceed their rate limits.
- API Gateway Implementation: Most API gateway security best practices emphasize configuring rate limits at the edge. This protects your backend services from being overwhelmed by abusive traffic.
6. Adopt Secure-by-Design API Development Practices
Security should be integrated into the API lifecycle from design through deployment. This “shift-left” approach reduces vulnerabilities before they reach production.
Best Practices:
- Design Phase: During the API design phase, conduct threat modeling exercises. Ask questions like, "How could this endpoint be abused?" and "What is the worst-case scenario if this data is exposed?"
- Development Phase: Provide developers with tools that can scan API specifications and code for security issues directly in their environment. An API vulnerability scanner integrated into the IDE or CI/CD pipeline can provide instant feedback, allowing developers to fix issues before they become part of the codebase. Our list of Top API Security Tools provides a comparison of platforms that streamline this workflow.
- Testing Phase: Automate API security testing as part of your CI/CD pipeline. This includes running DAST scans against staging environments to check for runtime vulnerabilities. For more details on this, see our in-depth guide on API Security Testing: Tools, Checklists & Assessments.
- Production Phase: Continuously monitor API traffic for anomalies and potential attacks. Real-time monitoring helps you detect threats that may have slipped through pre-production testing.
7.Scan your APIs Continuously
APIs ship fast, which means new vulnerabilities can appear at any time. Continuous scanning helps you catch broken access control, injection flaws, insecure GraphQL resolvers, and misconfigurations before attackers do.
In cases like this, a tool like Aikido can be of help. It helps with this by automatically discovering your APIs, scanning both REST and GraphQL endpoints for real vulnerabilities, and using techniques like fuzzing, traffic generation, and context-aware analysis to surface issues early. This gives teams full coverage of their attack surface and clearer, developer-friendly fixes.
Best Practices:
- Scan REST APIs: Test endpoints for authentication and authorization flaws, injection risks, insecure headers, misconfigurations, and weak validation.
- Scan GraphQL APIs: Check for excessive data exposure, missing authorization checks in nested resolvers, injection flaws, and schema-level weaknesses.
- Use automated discovery: Ensure your scanner can detect undocumented or shadow APIs so nothing is missed.
- Validate OpenAPI/Swagger accuracy: Outdated or incomplete specs lead to blind spots, so keep them updated or auto-generated.
- Integrate scans into your workflow: Run scans continuously or on every release, not quarterly.
8. Harden Error Handling and Logging
Error messages can be a goldmine for attackers if they reveal too much information.
Best Practices:
- Generic Messages: Return generic, non-descriptive error messages to the client. For example, instead of "Database connection failed for user 'admin'," simply return "An internal error occurred."
- Detailed Logs: Log the detailed error information on the server side for debugging purposes. This gives your team the information they need without exposing system internals to potential attackers.
9. Integrate Security Testing into CI/CD
Automation ensures that vulnerabilities are caught early and continuously throughout development.
Best Practices:
- Automate SAST, DAST, and IAST in your pipelines.
- Use AI to prioritize vulnerabilities and reduce noise.
- Automatically create tickets for remediation and enforce security gates.
- Combine automated tests with periodic manual penetration tests for business logic coverage.
10. Monitor APIs in Production for Anomalies and Misuse
The last thing you want to do is ignore your APIs just because they’ve been deployed. Even post-deployment, APIs remain targets, this is where real-time monitoring can help you detect any abnormal activity and emerging threats.
Best Practices:
- Use AI-powered anomaly detection to identify unusual request patterns.
- Monitor for business logic abuse, chained attacks, and spikes in traffic.
- Integrate monitoring with automated remediation where possible.
A Practical API Security Checklist
The following checklist will help you in accessing the current security posture of your APIs and your adherence to API security best practices:
Conclusion
API security can’t be a one-off effort. APIs grow and change as fast as the systems built on top of it, so protection must be an ongoing process.
Aikido Security helps teams stay ahead by scanning both REST and GraphQL APIs for authentication flaws, injection risks, excessive data exposure, misconfigurations, and business logic weaknesses. With automated API discovery, schema-aware scanning, and deep testing that integrates directly into CI workflows, Aikido gives engineering teams the clarity they need without slowing them down.
Ready to secure every API across your stack with one platform? Start your free trial or book a demo with Aikido Security today.
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