2026-08-31
A JWT debugger is one of those tools where "where does my pasted token go" actually matters — a decoded token often contains real user claims, session data, or internal identifiers.
| Tool | Decodes header/payload | Runs fully in your browser | Signature verification | Free |
|---|---|---|---|---|
| iLoveDevTools | Yes | Yes | View only (no server round-trip) | Yes |
| jwt.io | Yes | Partial (site loads a debugger UI, Auth0-hosted) | Yes, with secret/key input | Yes |
The JWT Debugger splits a token into header, payload, and signature the moment you paste it, with clear formatting on each section — no page reload, no request to a server, and no account. It's built for the common case: you have a token from a request or a log line and you want to see its claims immediately.
The original and most widely known JWT tool, maintained by Auth0. It goes further than most alternatives by letting you verify a signature against a secret or public key directly in the page, which is genuinely useful if you're debugging a signing mismatch rather than just reading claims.
If you need to verify a signature against a known key, jwt.io's verification UI is the more complete tool for that specific job. If you just need to decode and read a token's claims quickly — the far more common case — iLoveDevTools does it with one less concern about where the token content goes.