Base62 Encoder / Decoder
Encode and decode Base62 — the 62-symbol alphabet 0–9 A–Z a–z used by URL shorteners, database object IDs (e.g. YouTube, Flickr), and short link codes. Convert arbitrary text/bytes to a compact Base62 string and back, or convert an integer to and from Base62. Leading zero bytes are preserved (prefixed as 0 characters, mirroring how Base58 handles them). All arithmetic uses BigInt, so any length stays exact. Everything runs locally in your browser.
Output
Base62 maps bytes (or an integer) to the 62 characters 0–9 then A–Z then a–z. To encode bytes, the whole byte sequence is read as one big-endian integer and repeatedly divided by 62, the remainders indexing the alphabet; leading zero bytes would be lost, so they are instead emitted directly as leading 0 characters (and stripped back on decode). This is the same leading-zero trick Bitcoin's Base58 uses. Base62 avoids the visually-similar symbols Base58 drops (0/O, l/I) but is still URL- and filename-safe with no punctuation, making it popular for short identifiers. It is less compact than Base64 (log₂62 ≈ 5.95 bits/char vs 6) but has no +, /, or = padding. Pairs with the Base58, Base64, and Ascii85 tools. Everything runs locally — nothing leaves your browser.