OpenAPI to Protobuf (Proto3) Converter
Convert OpenAPI 3.x and Swagger 2.0 specifications into clean Protocol Buffers v3 message contracts in your browser.
At a glance
OpenAPI to Protobuf Converter transforms OpenAPI 3.x and Swagger 2.0 specifications into Protocol Buffers v3 (.proto) message contracts and gRPC services. It maps schema objects to messages, converts endpoints into RPC service methods, handles enums with default zero tags, and numbers fields sequentially in browser memory.
100% Client-Side In-Browser OpenAPI to Protobuf Converter
Compile OpenAPI 3.x and Swagger 2.0 specifications directly into strongly typed Protocol Buffers v3 (.proto) contracts and gRPC services in browser memory.
Generation Options
int32 / int64 formats preserved, array → repeated, additionalProperties → map<string, T>, and enum gets a default zero value.
Why Use This OpenAPI to Protobuf Converter?
How to Use OpenAPI to Protobuf Converter
Paste OpenAPI Specification
Enter or paste your OpenAPI 3.x or Swagger 2.0 JSON specification into the editor.
Configure Protobuf Options
Set package name, toggle gRPC service generation from paths, and configure Timestamp imports.
Copy or Export Proto
Review generated .proto file contents, copy to clipboard, or export as a .proto file.
OpenAPI to Proto3 Message & Service Output
Converts OpenAPI User model into a Proto3 message with sequential field numbering and generates a typed gRPC service for GET /users.
{
"openapi": "3.0.0",
"paths": {
"/users": {
"get": {
"operationId": "getUsers",
"responses": {
"200": {
"schema": { "$ref": "#/components/schemas/User" }
}
}
}
}
},
"components": {
"schemas": {
"User": {
"type": "object",
"properties": {
"id": { "type": "integer", "format": "int64" },
"name": { "type": "string" }
}
}
}
}
}
syntax = "proto3";
package api;
message User {
int64 id = 1;
string name = 2;
}
message GetUsersRequest {
}
service ApiService {
rpc GetUsers (GetUsersRequest) returns (User);
}
Technical Specifications & Engine Details
| Specification | Details |
|---|---|
| Supported Formats | APPLICATION/JSON, APPLICATION/YAML, TEXT/PLAIN, .JSON → TEXT/PLAIN, APPLICATION/X-PROTOBUF, .PROTO |
| Execution Mode | 100% Client-Side In-Browser (client) |
| Browser Requirements | Modern browser with JavaScript enabled. |
| Performance Constraints | Runs client-side in browser memory. Performance and file limits are bounded by available local device RAM. |
100% Client-Side Privacy Guarantee
Your files remain strictly on your local device. Zero data is transmitted to external servers.
Frequently Asked Questions
Are my OpenAPI specifications uploaded to an external server?
Does it support both OpenAPI 3.x and Swagger 2.0?
How does it handle date-time formats?
Can it generate gRPC services from API paths?
Methodology
This tool runs entirely in your browser. The example above shows a representative input and the result it produces.
Last updated .