Are my Firebase tokens sent anywhere?

No, all decoding happens locally in your browser ensuring your Firebase credentials remain secure.

Can I verify the signature?

Decoding and signature verification are different steps. You can see the claims without the private key.

JWT token

Optional public key (PEM)

Example

token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VyIjoiZGVtbyIsImlhdCI6MTcwMDAwMDAwMH0.signature

Run the tool to generate output.

The Firebase JWT Decoder allows you to inspect authentication tokens and specific claims from Firebase.

Open Firebase JWT Decoder and enter the source input you want to work with.
Run the tool once with a small sample so you can confirm the result format.
Copy, download, or reuse the output in your target app after a quick verification pass.

Inspect Firebase session token claims and expiration.

Verify your Firebase integration payload structure.

Debug authorization issues locally during Firebase development.