tool
Onion v3 Validator
Check whether a v3 .onion address is well-formed: decodes the base32, verifies the version byte and recomputes the SHA3-256 checksum exactly as the Tor spec defines. No network lookups: a valid address does not mean the service exists.
examples:
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Enter a .onion address to validate it.
ed25519 public key (32 bytes, hex)
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Version byte
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Checksum in address
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Recomputed checksum
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Spec (rend-spec-v3): address = base32(PUBKEY ‖ CHECKSUM ‖ VERSION) + ".onion", where CHECKSUM = SHA3-256(".onion checksum" ‖ PUBKEY ‖ VERSION)[:2] and VERSION = 0x03. The 56 base32 characters decode to 35 bytes.
Runs entirely in your browser — nothing is sent to any server.