Base58 Encoder
Encode text to Base58 (Bitcoin alphabet) or decode it back.
About this tool
Base58 Encoder
Encode text to Base58 (Bitcoin alphabet) or decode it back.
The Base58 Encoder converts ordinary UTF-8 text to and from raw Base58 using the Bitcoin alphabet. It treats the UTF-8 bytes as one big integer and repeatedly divides with BigInt so long values stay exact. The alphabet is 123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz; 0, O, I and l are omitted to reduce visual ambiguity. This is raw Base58, not Base58Check, WIF, encryption, or a wallet-key recovery tool.
How to use Base58 Encoder
- 1
Open Base58 Encoder on AltFTool — it loads instantly in your browser.
- 2
Type or paste your text into the 'Input' box — or click the 'Encode Hello' chip in the 'Examples' row to load a sample — then set 'Mode' to 'Encode to Base58' or 'Decode from Base58'.
- 3
The 'Result' panel updates live as you type; there is no submit button. Encoding converts the text to UTF-8 bytes and shows accurate 'Input bytes' and 'Output chars' counts, while decoding validates the Base58 characters and recovers UTF-8 text.
- 4
Use 'Copy' or 'Download' to keep the result — Download saves base58-encoder.txt containing the tool title, your Input and Mode, and the Result — or 'Reset' to put the Input back to its default 'Hello'.
Why use Base58 Encoder
BigInt arithmetic, not floating point
The base conversion runs on BigInt, so long inputs convert exactly instead of losing precision past 2^53.
Both directions in one field
Flip the mode select to decode the same box you just encoded from. Invalid alphabet characters and byte sequences that are not valid UTF-8 are rejected instead of silently altered.
Leading zero bytes are preserved
Each leading zero byte in the input becomes a leading 1 in the output and is restored on decode, which is the rule that keeps Base58 addresses stable.
Common use cases
- Round-trip a short UTF-8 identifier through the Bitcoin Base58 alphabet while testing an application.
- Compare a raw Base58 implementation against known ASCII and Unicode test vectors.
- Check whether a Base58 string decodes to valid UTF-8 text without treating it as a Bitcoin address or wallet key.
Frequently asked questions
What characters does the Base58 alphabet leave out?
Four: the digit 0, the capital letter O, the capital letter I, and the lowercase letter l. Removing them leaves 58 symbols that cannot be confused with each other when a value is read aloud or copied by hand.
How is Base58 different from Base64?
Base58 drops the four ambiguous characters and both non-alphanumeric symbols (+ and /), and uses no padding, so a value can be double-clicked, typed, or written down safely. The trade-off is size: Base58 output is longer than Base64 for the same data.
Why does a leading 1 appear in my encoded output?
Because the input began with a zero byte. Base58 encodes the value as a number, which would otherwise lose those leading zeros, so each one is written back as a literal 1 character at the front.
Is this the same Base58 used by Bitcoin addresses?
It uses the same alphabet, but a Bitcoin address is Base58Check — a version byte plus a 4-byte double-SHA-256 checksum appended before encoding. This tool does the raw Base58 conversion only, so it will not validate or generate a checksummed address.