When should I use it?
Use during auth debugging when you need to inspect claims safely.
Developer Data Toolkit
JWT Decoder
Advanced JWT inspection for API developers — decode locally, verify only with your secret.
Privacy-first — format, validate and inspect data entirely in your browser. Nothing is uploaded to FreeConverter.
✓ Browser Processing
✓ No Upload
✓ Privacy First
✓ Free Forever
✓ Works Offline
Tip: drag & drop a supported file onto this area.
Tool Options
Signature is never verified unless you provide a secret. Do not paste production secrets on untrusted devices.
Results
Results will appear here…
Building data migration or inspection workflows?
Continue with related FreeConverter.app developer tools — private, free, no registration.
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FreeConverter.app Guide
What does JWT Decoder do?
Decode JWT header and payload claims in the browser without sending tokens to a server.
Who is it for?
Developers, marketers, students, and anyone who needs a free browser utility.
Example input
Paste text, markup, or choose a local file (processed only in this browser tab).
Example output
Instant on-device result you can copy or download — nothing leaves your device.
Browser processing100% in-browser
PrivacyLocal Processing
UploadNot required
DifficultyEasy
How It Works
Inspector + formatter workflows for developers and QA.
1
Paste or upload
Paste data or drop XML, YAML, JSON, CSV, SQL or TXT. Nothing is uploaded to our servers.
→
2
Inspect & process
Format, validate or convert in your browser with structure stats and quality warnings.
→
3
Copy or download
Export TXT, JSON, YAML, CSV, SQL, Excel or ZIP instantly.
Your data stays on your device — format, validate and convert locally.
About JWT Decoder
Decode JWT header and payload with claims analysis, token age and security warnings (none alg, expired, missing exp/aud). Optional HMAC verify only when you provide a secret — 100% in browser. Part of FreeConverter’s Developer Data Toolkit for XML, YAML, CSV, SQL and API payloads.
FAQs
Decoding shows claims. Signature verification is a separate security step and may need your secret/JWKS.
No. Decoding is local.
Prefer non-production tokens. Even local tools can be shoulder-surfed — clear the field when done.
Modern browsers with atob/TextDecoder support.
Backend and frontend developers debugging OAuth/OIDC flows.
Pretty-print payload JSON with JSON Formatter after decoding.
No. The Developer Data Toolkit runs entirely in your browser. FreeConverter servers never receive your input.
Developers, DevOps, API engineers, DBAs and QA — for formatting, validating and inspecting structured data.
Yes. FreeConverter.app browser developer tools are free to use.
No. FreeConverter.app processes this tool locally in your browser. Your input is not uploaded to our servers.
No. JWT Decoder on FreeConverter.app is free to use without creating an account.
Developers, marketers, students, and anyone who needs a free browser utility.