Bencode is the simple binary-safe serialization format used by BitTorrent for .torrent files and tracker responses. It encodes four types: byte strings, integers, lists, and dictionaries, each with an unambiguous prefix so the data is self-delimiting.

How are the four bencode types written?

A byte string is its length, a colon, then the bytes (4:spam). An integer is i, the number, then e (i42e). A list is l, its items, then e. A dictionary is d, alternating key/value pairs, then e, with keys as strings sorted in raw byte order.

Why are dictionary keys sorted?

The spec requires dictionary keys to appear in sorted order so that any given data structure has exactly one canonical encoding. This is essential for computing a stable info-hash from a torrent file. This tool sorts keys lexicographically on encode.

Does bencode support floats or booleans?

No. Bencode has no native float or boolean type — only strings, integers, lists, and dictionaries. JSON booleans and floats cannot be represented, so this tool reports an error if you try to encode them.

Is my data uploaded anywhere?

No. All encoding and decoding runs locally in your browser using JavaScript, so torrent metadata and any private data stay on your device.

Bencode Encoder/Decoder

Bencode (pronounced “bee-encode”) is the minimal serialization format that powers BitTorrent — every .torrent file and tracker reply is bencoded. It supports just four types, each self-delimiting. This tool converts JSON to bencode and back, in your browser.

How it works

Bencode encodes four types with distinct prefixes:

Byte string — the byte length, a colon, then the data: 4:spam.
Integer — i, the base-10 number, then e: i42e (negatives allowed, no leading zeros).
List — l, each encoded element, then e: l4:spam4:eggse.
Dictionary — d, alternating encoded string-key/value pairs, then e. Keys must be sorted in raw byte order so each value has exactly one canonical encoding.

Decoding reverses this by reading the leading character to pick the type, then consuming exactly the bytes the prefix describes.

Tips and examples

The JSON object {"cow":"moo","spam":"eggs"} encodes to d3:cow3:moo4:spam4:eggse, with keys already in sorted order. The list ["spam", 42] becomes l4:spami42ee. Because bencode has no float or boolean type, encoding true or 3.14 is rejected. The sorted-key rule is what makes a torrent’s info-hash reproducible, so always trust the encoder’s ordering over your input order.