Base58 decode
Base58 decode. Runs on your device, nothing is uploaded.
Base58 decode treats the Bitcoin-style alphabet, which drops the confusable 0, O, I and l, as one big number and converts it back into bytes. Each leading character matching the alphabet's first symbol becomes a leading zero byte in the output, mirroring how Bitcoin addresses keep their leading zeros. An unrecognised character stops decoding and names its position.
Questions
What alphabet does it use?
The Bitcoin-style alphabet, which drops the easily confused characters 0, O, I and l.
How are leading zero bytes handled?
Each leading character equal to the alphabet's first symbol becomes one leading zero byte in the output, the same convention Bitcoin addresses use.
What happens with an invalid character?
The tool refuses, naming the character and its position.
Is this the same as Base64?
No, base58 uses a smaller alphabet and a big-number conversion rather than bit-packing, which is why it produces no visually confusing characters.
Can I use this from the command line?
Yes, the same code runs on the page, the CLI and MCP.