JSON to MessagePack encodes a JSON document as MessagePack — the compact binary format behind Redis protocol replacements, gRPC alternative RPCs and high-throughput message queues. Integers shrink to one byte when they fit, strings gain length prefixes, and maps and arrays use tiny fixed headers.
JSON to MessagePack
Encode a JSON document as MessagePack (msgpack) — the compact binary format with optimal integer packing.
Everything runs locally in your browser — your JSON never leaves this page.
JSON to MessagePack encoding rules
| JSON value | MessagePack encoding |
|---|---|
| 0–127 | single fixint byte |
| -32…-1 | single fixint byte |
| larger integers | int8/uint8 … int64/uint64, big-endian |
| 3.14 | float64 (0xcb + 8 bytes) |
| "text" (≤31 chars) | fixstr (1 byte) |
| longer strings | str8 / str16 / str32 |
| [ ... ] (≤15 items) | fixarray (1 byte) |
| { ... } (≤15 pairs) | fixmap (1 byte) |
| true / false / null | 0xc3 / 0xc2 / 0xc0 |
About JSON to MessagePack
Features
- Optimal integer packing: fixint, int8/uint8, int16/uint16, int32/uint32, int64/uint64.
- float64 for non-integer numbers.
- Compact strings: fixstr, str8, str16, str32 by length.
- Compact containers: fixarray/fixmap up to 15, then 16/32-bit headers.
- Three outputs: hex, base64 and a downloadable .msgpack file.
- Byte count shown for every encode.
- Private: All encoding happens in your browser.
How to Use
- Paste your JSON into the input box (or load the sample).
- Encode and review the hex output.
- Check the byte count against the JSON text size.
- Download the .msgpack file if you need the binary artifact.
Examples
Example 1 — Message queues. A backend engineer encodes event payloads as MessagePack to halve message size on a high-throughput queue.
Example 2 — Redis modules. A developer stores JSON documents as MessagePack strings in Redis to cut memory use.
Example 3 — Mobile APIs. A client engineer converts JSON responses to MessagePack for a low-bandwidth mobile API.
Example 4 — Protocol design. An architect encodes sample payloads to size out a binary wire format before implementation.
Benefits
- Smaller and faster: MessagePack beats JSON on both size and parse speed.
- Mature ecosystem: Official implementations for every language.
- Self-describing: No schemas or registries needed.
- Instant: Encoding happens in the browser in milliseconds.
- Zero upload: Data never leaves your machine.
Frequently Asked Questions
What is MessagePack?
MessagePack (msgpack) is a binary serialization format that is like JSON but faster and smaller. Small integers fit in a single byte, strings are length-prefixed, and arrays and maps use compact fixed-size headers.
How are numbers encoded?
Optimally: values from -32 to 127 use a single fixint byte, then int8/uint8, int16/uint16, int32/uint32 and int64/uint64 are used as needed — always big-endian. Non-integers become 64-bit floats.
Which output formats are available?
Hexadecimal text, base64 text, and a downloadable .msgpack binary file — all identical encodings of the same document.
Does MessagePack preserve key order?
Yes. Maps are serialized as an ordered sequence of key-value pairs, mirroring your JSON input exactly.
Is the output standard MessagePack?
Yes — the encoder emits only standard markers (fixint, str8/16/32, array16/32, map16/32, float64, nil, booleans). Any msgpack decoder reads it.
Is my JSON uploaded anywhere?
No. Encoding happens entirely in your browser. Nothing is uploaded, stored or logged.
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