What JSON to Protobuf Schema does
Generate a proto3 message definition from a JSON payload, with nested messages and numbered fields.
Also searched as protobuf schema, proto3, json to proto, generate proto, message definition, grpc schema, proto file.
Infer nested value types
Create stable message names
Number fields in encounter order
Field numbers are positional
Numbers follow the order keys appear in the payload. Protobuf treats a field number as permanent, so fix them before anyone depends on the schema.
One example cannot show optionality
Every field is emitted as singular and present. Mark optional and repeated fields yourself once you know the real contract.
JSON to Protobuf Schema FAQ
Does jsontools.me upload my JSON?
No. The document is parsed and processed by json-buf inside a dedicated WebAssembly worker on your device.
Does it work offline?
Yes. After the application shell and engine have loaded once, the installable PWA keeps the tools available without a network connection.