Base62 Encoder / Decoder
Encode text, hex bytes, or a decimal number to Base62 (0-9A-Za-z), or decode Base62 back — compact, URL-safe, no padding. Standard and inverted alphabets, arbitrary-precision numbers. Runs entirely in your browser, no server, no sign-up.
What this tool does
Encode any text, hex bytes, or a decimal number to Base62, or decode a Base62 string back to the original data — instantly, right in your browser. Nothing is sent to a server: it runs locally, works offline, and needs no sign-up. Pick a Mode, an Alphabet, and a Data format.
What is Base62?
Base62 represents data using the 62 alphanumeric characters — the digits
0-9, the uppercase letters A-Z, and the lowercase letters a-z. Because it
uses no padding (=) and none of the extra symbols that Base64 relies on
(+, /), a Base62 string is compact and safe to drop straight into a URL, a
filename, or a database key. That's why it's the go-to encoding for short IDs
and URL slugs — think the string in a shortened link.
Modes
| Mode | What it does |
|---|---|
| encode (default) | Turns your input into a Base62 string — e.g. Hello World! becomes T8dgcjRGkZ3aysdN. |
| decode | Reverses it — turns a Base62 string back into the original text, bytes, or number. |
Data format — text, hex, or number
| Format | When encoding | When decoding |
|---|---|---|
| text (default) | Reads the input as UTF-8 text | Renders the bytes as UTF-8 text (errors if they aren't valid UTF-8) |
| hex | Reads the input as a hex byte string (48 65 6c or 0x48656c) | Renders the decoded bytes as hex — use this for binary data |
| number | Reads the input as a non-negative decimal integer of any size | Renders the value back as a decimal integer |
Use number when you want to shorten an integer ID — for example turning the
database row 12345 into the slug 3D7, or a 128-bit counter into a handful of
characters. Numbers are handled at arbitrary precision, so values far larger
than 64 or 128 bits round-trip exactly.
Use hex whenever your data is binary and not readable text — for example a raw hash or a random token.
Alphabets
Base62 uses all 62 alphanumerics; the two common variants differ only in the order of the letters:
| Alphabet | Order | Notes |
|---|---|---|
| standard (default) | 0-9 A-Z a-z | Digits, then uppercase, then lowercase — the GMP order used by most short-ID libraries. |
| inverted | 0-9 a-z A-Z | Digits, then lowercase, then uppercase. |
Both variants have no padding. For byte input, each leading 0x00 byte is
preserved as a leading 0 in the output; for number input there is no
leading-zero padding (the integer 0 encodes to 0).
Examples
| Input | Settings | Output |
|---|---|---|
Hello World! | encode · standard · text | T8dgcjRGkZ3aysdN |
T8dgcjRGkZ3aysdN | decode · standard · text | Hello World! |
12345 | encode · standard · number | 3D7 |
4294967295 | encode · standard · number | 4gfFC3 |
516b6fcd0f | encode · standard · hex | 69hruW7 |
FAQ
Is it free and private?
Yes — your input never leaves your device, and it keeps working offline once the page has loaded.
What's the difference from Base64?
Base64 uses 64 symbols including +, /,
and = padding, which aren't URL-safe without extra escaping. Base62 sticks to
the 62 letters and digits, so its output needs no padding and is safe in URLs,
filenames, and IDs — at the cost of being slightly longer than Base64.
How is Base62 different from Base58?
Base58 drops the four visually
ambiguous characters 0 O I l (leaving 58), which makes it easier to read and
type by hand. Base62 keeps all 62 alphanumerics, so it's a bit more compact but
not optimised for hand-copying.
Which alphabet should I pick?
Use standard (0-9A-Za-z) unless a
specific library you're matching uses the inverted order. The two are not
interchangeable — a string encoded with one alphabet must be decoded with the
same one.
Can I shorten a big number?
Yes — set the Data format to number and paste the integer. There's no size limit; huge counters and UUID-sized values round-trip exactly.
My decoded output looks garbled.
The bytes probably aren't UTF-8 text. Switch the Data format to hex to see the raw bytes, or number if the value is an integer.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool base62-codec "Hello World!"New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/base62-codec/?input=Hello%20World%21&mode=encode&variant=standard&format=textMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.