Signature checker

Paste a request body or a webhook body. This page computes the signature step by step the way Cryptomus does, compares each step with yours and marks the first difference. Everything runs in your browser: this page cannot make network requests at all, so your API key never leaves your computer.

Request body: paste the exact JSON string you send (the signature covers it byte for byte, including spaces, newlines and escapes)

API key (same mode as the merchant; leave empty to see the first two steps)

The sign you computed (optional)

Your intermediate result (optional): the JSON string you encoded, or its base64. When a request is rejected for its signature, the 401 response's debug.body_base64 can go here too