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Bitcoin address validator
Check whether a legacy Bitcoin address is valid by verifying its Base58Check checksum and version byte. Detects mainnet vs testnet.
Input
Bitcoin address check
—Paste a legacy (Base58) Bitcoin address to verify its checksum.
A free Bitcoin address validator that verifies a legacy P2PKH address by decoding its Base58Check checksum and checking the version byte. It confirms the address is correctly encoded and identifies it as mainnet or testnet — entirely in your browser, nothing is sent anywhere.
How to validate a Bitcoin address
- Paste a legacy Bitcoin address (starts with 1 for mainnet, m or n for testnet) into the input.
- The tool Base58-decodes the address and verifies the embedded 4-byte checksum.
- It checks the version byte to identify mainnet vs testnet.
- Result shows valid (with network), invalid checksum, invalid length, or invalid characters.
What Base58Check validation confirms
Base58Check encodes 25 bytes: a 1-byte version prefix, a 20-byte payload, and a 4-byte checksum (the first 4 bytes of double-SHA-256 of the version+payload). Validation decodes the Base58 string, separates the checksum, recomputes it from the payload, and confirms they match. A passing result means the address is correctly encoded and the version byte identifies a known network. It does not confirm the address has ever been used, has a balance, or corresponds to any private key.
What this validator does not check
- Whether the address has ever appeared on the blockchain.
- Whether the corresponding private key exists or is known.
- Whether funds have been sent to or from the address.
- SegWit (bech32) addresses — those start with bc1 and use a different encoding scheme.
Frequently asked questions
What does Bitcoin address validation check?
It decodes the Base58Check encoding and verifies the 4-byte checksum. A valid result means the address is correctly formatted and not corrupted — it says nothing about blockchain activity or wallet ownership.
Does this tool support SegWit or bech32 addresses?
Currently only legacy P2PKH addresses (starting with 1, m, or n) are supported. SegWit addresses starting with bc1 use bech32 encoding, which is a different scheme.
What is the version byte?
The first byte of a decoded Bitcoin address specifies the network. 0x00 means mainnet (addresses start with 1), 0x6F means testnet (addresses start with m or n). Other values indicate different address types.
Does this tool transmit my Bitcoin address to any server?
No. The entire validation runs locally in your browser using JavaScript. Nothing is sent anywhere.