gRPC Proto Validator

It checks for: missing syntax declaration, missing package declaration, reserved field numbers (19000–19999 and 0), duplicate field numbers within a message, duplicate field names, field naming convention (snake_case), message naming convention (PascalCase), enum value naming (SCREAMING_SNAKE_CASE), enum first value must be 0 in proto3, missing language-specific options, and services without documentation comments.

In proto3, the default value for enum fields is always the first defined value with number 0. This is required so that unset fields have a predictable zero value. By convention, name this entry with a suffix like _UNSPECIFIED or _UNKNOWN (e.g. STATUS_UNSPECIFIED = 0) to make it clear that 0 means 'not set'.

The Protobuf library itself uses field numbers 19000–19999 for internal purposes. If your message uses these numbers, it will conflict with the runtime and cause unpredictable behavior. Always use field numbers outside this range.

Field names: snake_case (e.g. user_id, created_at). Message names: PascalCase (e.g. UserRequest, CreateUserResponse). Service names: PascalCase (e.g. UserService). RPC names: PascalCase (e.g. GetUser, ListUsers). Enum type names: PascalCase. Enum value names: SCREAMING_SNAKE_CASE with the enum type prefix (e.g. STATUS_ACTIVE, STATUS_INACTIVE).

Proto3 removes required/optional field modifiers (all fields are optional), uses simpler default values (zero/empty for all types), requires the first enum value to be 0, adds better JSON mapping support, and drops extensions in favor of 'Any'. Proto3 is recommended for new services. Proto2 is still supported but considered legacy.

No. All validation runs entirely in your browser using JavaScript. Your .proto file — which defines your API contract and data structures — never leaves your machine.