Use this base36 converter to encode text or numbers into Base36, or perform a base36 decode back to text or decimal. Base36 uses the digits 0-9 plus the letters a-z. It is shorter than decimal and stays alphanumeric, making it useful for compact IDs, invite codes, and URL-friendly values.
Text and number input modes
The base36 encoder handles two different jobs depending on your selected Input Type.
Text mode converts the UTF-8 bytes of the input string into one Base36 value. This mode is for strings, labels, and other byte-based input. It preserves the UTF-8 byte sequence, so decoding rebuilds the original text.
Number (Decimal) mode mathematically converts whole decimal integers into Base36. It also maps base36 to decimal when decoding. It uses BigInt internally, supporting integers far beyond standard JavaScript precision.
Alphabet and uppercase output
The base36 alphabet is 0123456789abcdefghijklmnopqrstuvwxyz. Unlike alphabets that use punctuation, Base36 is easy to paste into forms, spreadsheets, and filenames.
By default, the encoded output uses lowercase letters. You can toggle Uppercase output when encoding to use A-Z instead. The base36 decoder automatically accepts either case.
Batch conversion
If you need to process multiple items at once, enable Batch by newline. This reads one value per line and returns one output line per input line, making it easy to convert ID lists, test fixtures, or log samples.
Combine this with Trim lines to strip invisible leading or trailing spaces from each line before it gets converted. Failed lines return an inline error instead of stopping the whole batch.