API Fundamentals
API Security Best Practices for Public and Private Endpoints
A practical API security checklist covering authentication, authorization, validation, rate limiting, and monitoring.
Validate input and limit payload risk
APIs should never trust incoming data. Validation protects the application from malformed requests, injection attempts, and unexpected edge cases.
Strict input rules also make debugging easier for consumers.
Action checklist
- Validate required fields and data types.
- Reject oversized or malformed payloads.
- Sanitize data before it reaches internal logic.
Add rate limiting and abuse detection
Even well-intentioned consumers can create load spikes, and malicious actors can do much worse.
Rate limits, quotas, and anomaly detection help preserve service availability and reduce noisy traffic.
Action checklist
- Set request limits by identity or key.
- Watch for unusual burst patterns.
- Return clear throttling responses when limits are reached.
Log, monitor, and review regularly
Security is not a one-time configuration. Logs, alerts, and periodic reviews help catch bad behavior before it spreads.
Use monitoring to see who is calling the API, what they are asking for, and where errors are happening.
Action checklist
- Log authentication failures and permission denials.
- Alert on unexpected traffic or error spikes.
- Review API keys, tokens, and access rules on a schedule.