How do you handle API authentication securely in production apps?

Hi everyone,
I’m working on a web application and I want to understand the best practices for handling API authentication in production.

What are the most secure methods you recommend (JWT, OAuth, sessions, etc.) and how do you usually store and manage tokens safely on frontend and backend?

Would also appreciate any tips on common mistakes to avoid when implementing authentication systems.

Thanks!

Depends on your users/market needs, but as bullet points:

Prefers headless architecture (trust me, give you a favor for the future)
JWT (yep), but PASETO is an option if you want to have a confidential payload encrypted.
Remember to create access and refresh tokens with short TTLs.
Never store the JWT or similar in the db. First, verify the signature/expiration; then, if needed, compare it with the jti (ID) in your table/collection to extract user data (or the token payload)
Never set confidential info (email, name, etc) in the JWT payload, but userId, orgId, etc. is fine
Caution with the algorithm, sign the JWT with an explicit option
In frontend, prefer cookies httpOnly, but localStorage 🤷🏻‍♂️ : XSS, supply chain attack or 3rd party scripts
Handle access token expiration with 401, set interceptors in the frontend to fetch /renew and get a new token
In authentication, implement captcha. Otherwise, protect it against brute-force attacks with an incremental delay that ends with a temporal block per IP.
Wildcard suggestion: Put Cloudflare in front of your app and configure WAF rules.

Really solid breakdown, especially the points about short-lived access tokens, httpOnly cookies, and avoiding sensitive data in JWT payloads. I also agree that many projects underestimate brute-force protection and frontend token handling until it becomes a problem later.

Interesting mention of PASETO too not something people bring up often, but definitely worth considering depending on the architecture and security requirements.

Good question and one that trips up a lot of teams early on.

A few things that actually matter in production:

JWT is fine, but don't treat it as a session. Keep expiry short, 15 minutes is a common baseline, though your use case might call for less. Refresh tokens should live in httpOnly cookies, not localStorage. That one mistake alone accounts for a huge number of auth vulnerabilities in production apps.

Sessions still make sense for server-rendered apps, simpler to revoke, easier to manage. JWT shines more in stateless or API first setups. Pick based on your architecture, not the hype.

OAuth is the right call if you're dealing with third-party integrations. Don't roll your own if you don't have to. The surface area for mistakes is too large.

On the backend, never log tokens. Ever. It sounds obvious until you're debugging a prod issue at midnight and someone adds a catch-all logger.

The common mistake I see most is teams' focus on the happy path and forgetting token revocation. What happens when a user logs out? When a token is compromised? Having a clear invalidation strategy from day one saves a lot of pain later.

Start simple, but think about rotation and revocation before you go live, not after.

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How do you handle API authentication securely in production apps?

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How do you handle API authentication securely in production apps?

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