jwtpeek

A tiny, no-nonsense, clipboard-based JWT inspector for the terminal.

jwtpeek reads a JWT from your clipboard, decodes the header and payload, and prints them in a clean, readable format.
No browser tabs. No network calls. No ceremony.

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Features

• Decode JWT header and payload
• Works on text containing JWTs (logs, curl commands, headers, etc.)
• Clear expiry information (expired / expires soon)
• Optional clipboard write-back of payload JSON
• Colored output (TTY only)
• Works fully offline

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Installation

From source

git clone https://github.com/Lillevang/jwtpeek.git
cd jwtpeek
crystal build src/jwtpeek.cr --release

This produces a jwtpeek binary in the current directory. You can then move it somewhhere on your PATH:

mv jwtpeek ~/.local/bin

Usage

1. Copy a JWT (or text containing one) to your clipboard
2. Run:

jwtpeek

Optional: copy the decoded payload JSON back to the clipboard:

jwtpeek --copy  

Example output

HEADER
──────
{
  "alg": "HS256",
  "typ": "JWT"
}

PAYLOAD
───────
{
  "sub": "1234567890",
  "name": "John Doe",
  "admin": true,
  "iat": 1769379926
}

iat: 2026-01-25T22:25:26Z (in 23h 47m)

SIGNATURE
─────────
bytes: 32 (not verified)

⚠ token expires soon
✔ payload copied to clipboard

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Notes

• JWT signatures are not verified (yet)
• The tool is intended for inspection and debugging
• No configuration files
• No network access

Roadmap (rough)

• Signature verification (HS256 / RS256 / ES256 / etc)

License

MIT

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Created by

Jeppe Lillevang Salling https://github.com/Lillevang