JWT Decoder
Decode JWT header, payload, and signature fully client-side, with formatted JSON and copy/download.
JWT Input
Decoded
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Frequently Asked Questions
Is my token uploaded?
No, decoding happens entirely in your browser.
Do you verify signatures?
Not in MVP; decoding only. Verification can be added.
JWT Decoder: Safely Inspect JSON Web Tokens
JSON Web Tokens (JWTs) are widely used for authentication and API authorization, but debugging them in production can be risky if you send tokens to third‑party services. This JWT decoder runs entirely in your browser so you can inspect headers, payloads, and signatures without exposing secrets or user data.
Use it during development, incident response, or integration work to quickly verify claims, expiry times, and audience/issuer alignment. For security‑sensitive environments, pair it with our Base64 Encoder / Decoder to debug encoded segments or JSON Formatter to explore complex nested payloads.
JWT Debugging Best Practices
✅ Recommended checks
- • Confirm token is signed with the expected algorithm
- • Verify
iss,aud, andsubclaims - • Check
expandnbftimestamps - • Validate custom claims match your environment (tenant, role, scope)
❌ Avoid unsafe patterns
- • Never paste production tokens into online tools that send data to servers
- • Don't rely on decoding alone to verify authenticity—always validate signatures in code
- • Avoid logging full tokens in application logs