JSON to MessagePack Converter
Convert JSON to MessagePack binary format. See hex dump, Base64 encoding, and size savings compared to JSON. MessagePack is a fast, compact binary serialization format used in Redis, gRPC, and real-time APIs.
Features
đĻ Pure MessagePack v2.0
- Full MessagePack specification v2.0
- Handles all JSON types: null, bool, int, float, string, array, object
- Compact fixint, fixstr, fixmap, fixarray types
- Hex dump with 16-byte rows
đ Size Analytics
- Compare JSON bytes vs MessagePack bytes
- Percentage size reduction shown
- Base64 encoding of the binary output
- Download as raw .msgpack binary
đ Privacy-First
- All encoding happens in your browser
- No data sent to servers
- Works offline after first load
- Suitable for sensitive data
About MessagePack
MessagePack is a binary serialization format designed to be faster and more compact than JSON. It is used in Redis for caching, FluentD for log data, game engines for network messages, and many real-time API systems. MessagePack can be up to 4Ã smaller than equivalent JSON for numeric-heavy data.
Unlike JSON, MessagePack is a binary format and is not human-readable. This tool shows both the raw hex dump and Base64 encoding so you can inspect or transmit the encoded data as text. Libraries for decoding MessagePack are available in every major language.
Frequently Asked Questions
Why is MessagePack smaller than JSON?
JSON encodes everything as text â a number like 1000000 takes 7 bytes as a string but only needs a few bytes as binary. MessagePack also skips the quotes and colons around string keys and uses compact single-byte headers (fixint, fixstr, fixmap) for small values, which is where most of the size reduction comes from on typical API payloads.
What's the difference between the hex dump and Base64 output?
The hex dump shows the raw bytes for inspection and debugging (useful when writing or verifying a decoder). The Base64 string is the same binary data re-encoded as printable text, which is what you'd actually embed in a JSON field, URL, or any transport that can't carry raw binary safely.
Can I decode this output back to JSON?
Yes â any MessagePack-compliant decoder (msgpack-python, msgpack-javascript, msgpack for Go, etc.) can read the downloaded .msgpack file or the raw bytes behind the Base64 string and reconstruct the original JSON structure exactly, since MessagePack preserves all the same types JSON does.
When should I use MessagePack instead of JSON?
When payload size or parse speed matters more than human-readability â internal service-to-service calls, WebSocket message framing, mobile app payloads on metered connections, or caching layers like Redis where every byte and CPU cycle counts. For public APIs where developers need to read responses directly, JSON usually remains the better choice.