Format a .proto file

Indent Protocol Buffer declarations and separate major blocks for a readable .proto file.

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ToolProtobuf Editor
Input
Output
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Preview

How it works

The formatter adjusts a two-space indentation level around braces and inserts blank lines before top-level message, service, enum, and oneof blocks. Comments and declaration text are preserved without parsing a descriptor.

  • Two spaces are fixed for predictable generated output.
  • Unknown declarations are indented rather than semantically rewritten.

Worked example

User message with name and age fields
Format a Protocol Buffer message definition with proper indentation
Input
											syntax = "proto3";

message User {
string name = 1;
int32 age = 2;
}
Output
												syntax = "proto3";

message User {
  string name = 1;
  int32 age = 2;
}

When to use this

gRPC interfaces, code-generation schemas, and reviewed API contracts use .proto files.

Edge cases

  • A brace in a quoted option can confuse this line-based formatter.
  • Comment text is retained but not reflowed.
  • Nested blocks increase indentation by braces even with unusual option layout.

References