Protobuf → JSON Decoder

A free, browser-only tool to decode Protobuf binary data into readable JSON. Supports proto3 schemas, hex & base64 input, automatic zstd / gzip decompression, nested message type trees, and syntax-highlighted output.

No data is sent to any server — everything runs locally in your browser.
i How to use ▸
1. Proto schema — paste your .proto file contents or load it with Load .proto. The schema is parsed automatically on paste or file load.
2. Binary data — paste hex or base64 into the corresponding tab, or load a binary file.
   Raw, zstd-compressed, and gzip-compressed data are all supported — compression is detected automatically.
3. Select the message type — the root type is auto-selected after parsing.
4. Click Decode →.

Note: on first load the page initialises Go WASM (~1 sec). If decoding fails immediately, wait a moment and try again.

Proto Schema

no file
Paste proto schema or base64 descriptor / load file

Binary Data

File
Hex
Base64
no file
Raw protobuf binary file
Hex string (spaces optional)
Base64-encoded protobuf data
Message type: 
Output will appear here...