Developer Data Tools
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JWT tool

JWT Decoder / Validator

Decode JWT headers and payloads locally, inspect claims and check basic expiration timing without verifying signatures.

Tool Workspace

This tool runs in your browser. Developer Data Tools does not save pasted input to a server, but avoid using production secrets, access tokens, private keys or sensitive business data in any online page.

Ready. Processing runs in your browser.

Core Features

  • Decode Base64URL JWT sections.
  • Show header, payload and basic exp status.
  • Generate unsigned test tokens for local demos.
  • Keep token text in the browser.

Common Errors

  • Confusing decoding with signature verification.
  • Pasting production access tokens into online pages.
  • Trusting alg=none or unverified claims.

Real Developer Use Cases

  • Inspecting local test tokens.
  • Checking exp, iat, aud and iss claims.
  • Explaining why decoded JWT payloads are not proof of validity.
JSON Formatter & Validator

Format and validate copied API responses.

Text Diff Checker

Compare generated output and source snippets.

Base64 Encoder/Decoder

Inspect encoded data fragments.