JWT vs API Key Authentication
JWT and API keys both authenticate requests. When to use each—stateless vs stateful, revocation, and use cases.
What this problem means
You need to authenticate API requests. Two common options: API keys (static secrets) and JWTs (signed tokens). Both work, but they have different strengths and trade-offs.
Why this matters
- Security: Weak auth leads to abuse and data access.
- Revocation: API keys are easy to revoke. JWTs are harder—they're valid until expiry.
- Stateless: JWTs are stateless; the server doesn't need to look up the key.
Real-world example
A startup used API keys for their B2B API. When a customer's key was leaked, they revoked it immediately. Simple. Another team used JWTs with 24-hour expiry. When they needed to revoke a compromised token, they had to wait—or add a blocklist (which adds state).
How to choose
API keys when you need:
- Simple revocation (delete the key)
- B2B or server-to-server
- Per-key rate limiting or quotas
- No user session (machine-to-machine)
JWTs when you need:
- Stateless auth (no DB lookup per request)
- User sessions (short-lived tokens)
- Claims (user ID, roles) in the token
- Microservices (pass token between services)
Tools and configurations
- API keys: Store hashed in DB. Validate on each request. Revoke by deleting.
- JWTs: Sign with HS256 or RS256. Set short expiry (e.g., 15 min access + refresh token).
- Both: Use HTTPS. Never log tokens or keys.
Common mistakes
- JWTs with long expiry (hard to revoke).
- API keys in frontend code (use backend proxy).
- No rate limiting per key or token.
Quick checklist
- [ ] Use API keys for B2B, JWTs for user sessions
- [ ] Short JWT expiry (15 min) + refresh token
- [ ] Store API keys hashed, never in frontend
- [ ] Rate limit per key or token
- [ ] HTTPS only
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Frequently asked questions
- When should I use JWT vs API key?
- Use API keys for B2B or server-to-server when you need simple revocation. Use JWTs for user sessions when you need stateless auth and claims in the token.
- How do I revoke a JWT?
- JWTs are valid until expiry. To revoke: use short expiry (15 min) + refresh token, or add a blocklist (adds state). API keys are easier to revoke—just delete the key.
- Are API keys or JWTs more secure?
- Both can be secure. API keys are easier to revoke. JWTs are stateless but harder to revoke. Use short expiry for JWTs. Never put either in frontend code.