JWT Signer

JWT Signer is a free online Security Tools tool that seal a payload with RS256 (or HS256/HS384/HS512 and ES256) right in the browser: paste claims and a PKCS#8 private key — or generate an RSA/EC pair on the spot — then verify the result on the same page. "none" is never accepted, and your keys never leave this machine instantly in your browser. Paste your data, adjust the options and get the result in real time — no installation, no sign-up, and nothing is ever uploaded to a server.

How to use: JWT Signer →

Description

Seal a payload with RS256 (or HS256/HS384/HS512 and ES256) right in the browser: paste claims and a PKCS#8 private key — or generate an RSA/EC pair on the spot — then verify the result on the same page. "none" is never accepted, and your keys never leave this machine.

  • Because everything is computed client-side, JWT Signer is safe to use with sensitive data such as API keys, tokens or private logs.

How to use

Using JWT Signer takes three steps:

  1. Paste your data into the input box (or load the example).
  2. Configure the options to match your target format or scenario.
  3. Copy, download or inspect the output — it updates live as you type.

Use cases

Common situations where JWT Signer helps:

  • Seal a payload with RS256 (or HS256/HS384/HS512 and ES256) right in the browser: paste claims and a PKCS#8 private key — or generate an RSA/EC pair on the spot — then verify the result on the same page. "none" is never accepted, and your keys never leave this machine.
  • Because everything is computed client-side, JWT Signer is safe to use with sensitive data such as API keys, tokens or private logs.

FAQ

What is JWT Signer?

JWT Signer seal a payload with RS256 (or HS256/HS384/HS512 and ES256) right in the browser: paste claims and a PKCS#8 private key — or generate an RSA/EC pair on the spot — then verify the result on the same page. "none" is never accepted, and your keys never leave this machine. It runs entirely in your browser, so your data stays private.

Is JWT Signer free to use?

Yes. JWT Signer is free, unlimited and works without registration or installation.

Does my data get uploaded?

No. All processing happens locally in your browser; nothing is sent to any server.

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