Encode, decode and validate Base58Check with version byte and checksum
Base58 is a binary-to-text encoding that uses 58 alphanumeric characters, deliberately dropping 0 (zero), O (uppercase o), l (lowercase L) and I (uppercase i), exactly the ones people confuse when reading. It was created by Satoshi Nakamoto for Bitcoin addresses and shows up in cryptocurrencies, in IPFS (CIDv0) and in any system where an identifier will be typed or spoken by a human. Plain Base58, however, does nothing against typos: that job belongs to Base58Check, which puts a version byte in front of the payload and four checksum bytes (the first four of a double SHA-256) at the end. This tool does both directions, verifies the checksum instead of silently accepting corrupted input, and accepts input as text or as hexadecimal bytes, which is how Base58Check is actually used.
A Base58Check string is not an indivisible blob. Before encoding, it is the concatenation of three parts: a version byte, saying what kind of object it is and on which network; the payload, usually a 20-byte hash or a 32-byte key; and four checksum bytes, the first four of SHA-256 applied twice over version plus payload. Only then does the whole thing become Base58, with every leading zero byte turning into the first symbol of the alphabet.
That is why the validation tab shows the fields separately. When the checksum fails, the payload is almost always fine and one character was swapped, or the string was truncated. Seeing version, payload and both checksums side by side turns a generic error into a diagnosis: a P2PKH address is 25 bytes in total, 1 of version, 20 of payload and 4 of checksum, and anything outside that already tells you where to look.
In Bitcoin, Base58Check encodes legacy addresses and private keys in WIF format. Newer bech32 addresses do not use Base58, but the installed base of legacy addresses is still enormous, and WIF keys remain the most common wallet export format.
In IPFS, a CIDv0 is a SHA-256 multihash encoded in Base58 with the Bitcoin alphabet, which is why it always starts with Qm. CIDv1 moved to lowercase Base32, which is case-insensitive and fits a DNS label. Outside that world, the Flickr alphabet was used to generate short photo identifiers, and the Ripple one shows up in that network addresses. In every case the reason to pick 58 symbols is the same: someone, at some point, will have to read or type the thing.
Paste the code into your HTML and the tool shows up on your page, without J-Kit's navigation and ads. It still runs in the browser of whoever visits your site.
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></iframe>These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
Base58 drops 0 (zero), O (uppercase o), l (lowercase L) and I (uppercase i) because they look alike in common fonts and are hard to tell apart when read aloud. That reduces transcription errors, which is critical for wallet addresses, where one swapped character can mean permanently lost funds.
123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyzEverything is computed in your browser, including the SHA-256 behind the checksum. No key or address leaves this device.