Base62 encoder.

Base62 writes a number with all 62 letters and digits, 0 to 9, A to Z then a to z, and no symbols. It is the densest alphabet that needs no escaping anywhere: not in a URL, a file name, a JSON string or a shell. The tool treats the input bytes as one big number and writes that.

The bytes are read as one integer, big end first, and written in base 62 by repeated division. Each character carries about 5.95 bits, so the output is about 34% larger than the input, close to Base64. Leading zero bytes are kept as leading 0 characters. There is no padding.

URL shorteners (bit.ly's slugs), short unique ids, invite and referral codes, session and API tokens, and anywhere a 64-bit id has to become an 11-character string that fits a URL untouched.

Yes: letters and digits only, nothing to escape.

Nearly as short as Base64 with none of its symbols, which is why web ids use it; but case-sensitive, so a person transcribing it can slip, and converted as one number, so it is slow on anything big. Base58 drops the look-alike characters for the same job; Base36 drops case; Base64 streams.

No. Base62 is an encoding, not encryption: it changes how bytes are written, not who can read them, and anyone can decode it with no key. Encrypt first (AES, age, a library's sealed box) when the content needs protecting, then encode the ciphertext if it has to travel as text.

Type or paste into the input and the Base62 appears as you type: "Hello" becomes 5TP3P3v. Text is encoded as UTF-8 bytes, so accents and emoji come out the same as in every language's standard library. Copy the result, download it as a text file, or press Swap to decode it back.

Drop a file onto the input or choose one with the button, and its bytes are encoded directly, not as text. Base62 treats the whole input as one number, so the tool takes up to 512 KB at once; past that the conversion would stall the page.

Nothing leaves your browser. The text or file is read into memory on your machine and the encoding is computed there, in plain JavaScript; the page makes no request with it. Load the page, go offline and it keeps working.

No. The Base62 encoder is free and opens without a sign-in, an account or an install.

Nothing. The Base62 encoder holds your input in the page's memory, so closing or reloading the tab clears it, and it saves nothing in this browser.

None: Base62 has a single alphabet, so the encoder has no choices to make.

Base62 output is about 1.34 characters per byte, and the status line under the result shows the bytes in, the characters out and the percentage. Base62 treats the input as one number, so the tool takes up to 512 KB at once.

The text is encoded as UTF-8 bytes first, so accented letters, other scripts and emoji round-trip through the decoder unchanged. Each of those characters takes more than one byte, which makes the output longer than the character count suggests.

Press Swap once there is a result and the same tool becomes the Base62 decoder, with the output moved into the input. The decoder shows the original text again.

Closest to the Base62 encoder: Base62 decoder, File to Base62, Base62 to file, Base58 encoder. Each opens on its own page, free and in the browser.

The Base62 encoder is one of 32 in its group. The group's page, /tools/encoding, lists them all.

The tool is free. Its interface is built from shadcn.io's own components (Button, Input, Slider and the rest of the registry under /ui), which come in React, Vue, Svelte and Solid. Pro adds the blocks and templates for the product around it.