Wallet Import Format (WIF)

WIF (Wallet Import Format) is a Base58Check encoding of a single Bitcoin private key. It wraps the raw 32-byte private key with a network prefix byte, an optional compression flag, and a 4-byte checksum so a typo at the wallet import screen fails fast instead of silently loading a different key.

What WIF strings look like:

• 5... - uncompressed-public-key form. Legacy; only present in pre-2012-ish wallets and a few collector wallets.
• K... or L... - compressed-public-key form. The standard format for modern WIF.
• p2... (or other prefixes) - BIP 38 encrypted private keys: a WIF protected with a passphrase. The user must decrypt before use.

Where you still encounter WIF in 2026:

• Sweeping a paper wallet. Older paper wallets stored a single WIF; importing it into a modern wallet moves the coins to your HD-managed addresses.
• One-off private key recovery. A long-dormant address resurfaces, you have the raw private key somewhere, and you need to spend it once.
• Educational tools. Some teaching wallets and Bitcoin developer playgrounds use WIF because it's compact and human-readable.

WIF is a single-key format. There's no derivation, no tree, no children. If you import a WIF and then spend from the resulting address, modern wallets typically don't track future addresses derived from any related key - because there isn't a related key tree. For ongoing custody, modern practice is BIP 39 mnemonic seed phrases driving BIP 32 HD wallets. WIF lives on as the legacy single-key compatibility format.

Security note: a WIF is exactly as sensitive as a raw private key. Anyone with the string can spend the coins. Treat it like cash, not like a public address.