Decode MessagePack binary into JSON-compatible values (maps, arrays, strings, bins, ext, nil, bool, int, float) entirely in your browser.
Privacy: Decoding runs entirely in this tab. Your bytes and optional schema text are not uploaded to Codeground servers.
Binary payload
Decoded output
{
"name": "Ada",
"id": 42
}MessagePack is a compact binary cousin of JSON used in Redis, RPC, and game protocols. Paste Base64 from logs or hex from a packet dump and inspect the structure without installing a CLI.
This decoder walks fixmap/fixarray/str/bin/ext and the larger type formats, then prints JSON you can copy into other tools.
Paste Base64, hex, or PEM (for ASN.1). Auto-detect treats even-length hex strings as hex; otherwise Base64 is assumed. Whitespace is stripped automatically.
Do you upload my binary payloads? No. Decoding runs entirely in your browser. Bytes and optional schemas never leave this tab.
What MessagePack types are supported? nil, bool, integers, floats, strings, binary, extension types, arrays, and maps (including fix* and length-prefixed forms).
Is MessagePack the same as JSON? No. MessagePack is binary and more compact, but values map cleanly to JSON for debugging.
What input formats work? Base64 or hex, with auto-detect. Whitespace is stripped automatically.
Related: Protobuf decoder · MessagePack · CBOR · Base64 decode · JSON formatter