JOSE/JWT libraries usually want keys in JWK (JSON Web Key) format, while OpenSSL and most TLS tooling produce PEM. Converting between them normally means writing a script — this tool does it directly in your browser with the Web Crypto API.
What Is the JWK ⇄ PEM Key Converter?
Paste a PEM key or a JWK JSON object, choose the key type (public/private) and algorithm (RSA or EC), and convert it to the other format — no key ever leaves your browser.
How to Use It
- Open the tool at /tools/jwk-converter.
- Choose your conversion direction, key type, and algorithm.
- Paste your PEM or JWK input.
- Click Convert and copy the result.
Key Features
- Real Web Crypto API conversion, not a hand-rolled parser.
- RSA and EC (P-256) support.
- Entirely client-side — private keys never touch a server.
- Clear error messages when a key/format/algorithm combination doesn’t match.
When to Use This Tool
- Converting an existing PEM key for use with a JOSE/JWT library that expects JWK format.
- Converting a JWK from an identity provider’s JWKS endpoint into PEM for use with OpenSSL-based tooling.
- Learning the structural difference between PEM and JWK key representations.
Try It Now
Open JWK ⇄ PEM Key Converter directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Security & Crypto collection on WebdevToolbox — free, browser-based developer tools with no login required.