Paste a public key, a message and a signature. The verifier auto-detects the curve, the signature format (DER or raw r‖s) and the encoding, then checks the signature locally.
100% local — everything runs in your browser, nothing is sent to any server
This free ECDSA signature verifier checks a digital signature against a public key and a message, entirely in your browser — no key, message or signature ever leaves your machine. It accepts public keys as PEM (SPKI), JWK or raw SEC1 points, and signatures in DER (ASN.1) or raw r‖s form, in hex or base64, detecting the format and encoding automatically. The curve — P-256, P-384, P-521 or secp256k1 — is read from the key when possible, or inferred by trying every curve that fits the key length. The message is hashed with SHA-256, SHA-384 or SHA-512 (or treated as a precomputed digest), and the signature is verified with the audited @noble/curves library. It also flags non-canonical high-S signatures that Bitcoin and several other ecosystems reject.