Bitcoin Address Validator

Bitcoin address formats: Legacy, P2SH, SegWit and Taproot

A Bitcoin address encodes the destination for a payment. Over Bitcoin's history several formats have appeared, each recognisable by its prefix. This tool checks the structural format — prefix and character set — and reports the address type; it does not (and a client should) verify the cryptographic checksum.

The four mainnet families

• Legacy P2PKH — starts with 1, Base58Check, 26–34 chars. The original "pay to public key hash".
• P2SH — starts with 3, Base58Check. "Pay to script hash": multisig, or older wrapped-SegWit.
• Native SegWit (bech32) — starts with bc1q; P2WPKH (~42 chars) or P2WSH (~62 chars). Lower fees, defined in BIP 173.
• Taproot (bech32m) — starts with bc1p, defined in BIP 350. Better privacy and smart-contract flexibility.

Two different checksums

• Base58Check (Legacy / P2SH): the last 4 bytes are a double-SHA-256 checksum; Base58 omits 0, O, I, l to avoid visual confusion.
• Bech32 / bech32m (SegWit / Taproot): a BCH-code checksum over a lowercase charset (qpzry9x8…) that detects most typos and is case-insensitive (but never mixed-case).
• Why it matters: a real wallet verifies the checksum before sending — format alone is not enough to prove an address is spendable.

Gotchas

• Case rules differ: Base58 is case-sensitive; bech32 must be all-lowercase (or all-uppercase) — mixed case is invalid.
• Prefix ≠ ownership: a valid format says nothing about who controls the keys or whether funds exist.
• Testnet looks different: testnet uses m/n, 2 and tb1 prefixes — don't send mainnet funds to them.
• bech32 vs bech32m: SegWit v0 uses bech32; Taproot (v1) uses bech32m. Using the wrong constant makes a valid-looking address fail checksum.

FAQ

Does a valid format mean the address is real? No. Only the Base58Check or bech32 checksum confirms the address isn't a typo; existence of funds requires a chain lookup.

Why are bc1 addresses cheaper to spend from? SegWit moves signature data into the witness, reducing the weight that counts toward fees.

Can I send to any address type? Yes, modern wallets pay all four types; only very old wallets may not recognise bc1p Taproot.