protolint.com

Validate your Protocol Buffers

Check your .proto files against the Google Protocol Buffer style guide. Catch naming issues, structural problems, and style violations instantly.

editor.proto

Drag & drop a .proto file or paste content above

Results

Click "Validate" to check your .proto file

Style Rules Checked

Syntax Declaration

Files must declare syntax version

Package Name

Package should be declared

PascalCase Names

Messages and enums use PascalCase

snake_case Fields

Field names use snake_case

UPPER_SNAKE_CASE Enums

Enum values use UPPER_SNAKE_CASE

Enum UNSPECIFIED

First enum value should be UNSPECIFIED = 0

Import Ordering

Public imports come first

Service Comments

Services and RPCs should have comments

Line Length

Lines should not exceed 80 characters

Trailing Newline

Files should end with a newline

API

Integrate protolint into your CI/CD pipeline or tooling.

POST /api/validate

# JSON body
curl -X POST https://protolint.com/api/validate \
  -H "Content-Type: application/json" \
  -d '{"content": "syntax = \"proto3\";\npackage example;"}'

# File upload
curl -X POST https://protolint.com/api/validate \
  -F "file=@path/to/your.proto"

Response

{
  "valid": true,
  "errors": [],
  "warnings": [
    {
      "line": 5,
      "column": 81,
      "rule": "max-line-length",
      "message": "Line exceeds 80 characters (92).",
      "severity": "warning"
    }
  ],
  "info": []
}