⌘ K
protobuf · .proto · indent · live

Format Protobuf schemas

Basic indenter for .proto schema files — tracks {, [, ( depth. For production use buf format or clang-format-proto. Runs locally.

Protobuf Formatter
Input
79 B
1 lines
Output
80 B
2 lines
Status
ready
live
Ratio
1.01×
out/in
input · proto
output · formatted proto
syntax = "proto3";message User{int64 id=1;string name=2;repeated Post posts=3;}
Quick Start

How to format Protobuf

A brace-tracking indenter — counts {, [, ( open/close to lay out message and service definitions consistently.

  1. 01

    Paste schema

    A single .proto file with messages, enums, oneof blocks, services, or RPC methods.

    Parsing runs through Prettier’s standalone bundle (or the language-specific equivalent) loaded lazily — no parser ships until the tool is opened.

    protoPrettierASTstandalonelazy
    input · sourceraw · AST
    message M{int32 id=1;}
    loaded · parsedAST · ready
  2. 02

    Set indent width

    4 spaces is the buf default. Tabs are not produced — spaces only.

    Indent width, tab style, and print-width re-format through a memoised pass — switching 2 → 4 spaces never re-parses, only re-prints.

    optionsindentprint-widthmemoisedlive
    opts · optionsindent · live
    indent=4
    options applied · livelive
  3. 03

    Watch blocks align

    Fields inside message / oneof indent, RPC method signatures wrap onto multiple lines.

    The formatter is deterministic and idempotent: running it twice produces byte-identical output, which keeps diffs and git noise to a minimum.

    liveidempotentdeterministicdiff-cleanstable
    out · formattedindented · ready
    message M {
    int32 id = 1;
}
    formatted · liveidempotent
  4. 04

    Copy or download

    Save as .proto or copy to clipboard. Source stays in your browser.

    Download writes a Blob with the language-appropriate extension; copy uses navigator.clipboard.writeText so the output preserves all whitespace exactly.

    exportclipboardbloblanguage MIMEclient-side
    ok · copiedready · done
    OK Copied
    shipped · ready to shipsuccess
Pro tips

Formatting tips that keep diffs sane

Pick one config and pin it

Inconsistent formatting causes diff churn. Commit .prettierrc / .editorconfig and enforce in CI.

Format on save

Editor integration is faster feedback than a pre-commit hook. Use both for belt-and-braces.

Idempotency matters

Running the formatter twice should produce identical output. Test this on a representative file.

Match the language community

Default to community conventions: 2 spaces for JS/CSS, 4 for Python, tabs for Go. Fights over indent are a productivity tax.

Print-width drives wrapping

80, 100, and 120 are the common targets. Wider lines parse fast but review slower side-by-side.

Don’t mix formatters and linters

Prettier handles whitespace; ESLint handles correctness. Disable overlapping rules to avoid fight-club configs.

Related toolsGraphQL FormatterPrisma FormatterOpenAPI FormatterJSON FormatterYAML FormatterRust Formatter
Use Cases

When to format Protobuf

gRPC services, schema reviews, docs examples.

gRPC services

Re-indent .proto files before generating stubs. Idempotent: running the formatter twice produces byte-identical output, which is the foundation of a clean CI gate. Pair with a pre-commit hook so PRs arrive already formatted, focusing review on logic.

idempotent

Schema reviews

Tidy whitespace before opening a buf PR. Pairs with EditorConfig + .prettierrc for end-to-end consistency. Whitespace-only changes vanish so reviewers see real diffs, and git blame stays honest about who wrote what.

CI-ready

Snippet sharing

Format a message excerpt for chat or issues. Output respects your indent width, tab style, and print-width — settings carry over for repeat runs. Switching 2-space to 4-space costs nothing in CPU but standardises an entire codebase.

diff-clean

Migration cleanup

Re-indent after a bulk text replace. Format-on-save is the fastest feedback loop; CI is the safety net. Together they make inconsistent indentation a thing of the past and free up review cycles for genuine concerns.

PR-friendly

Quick fix

Reformat after pasting a one-liner from docs. Whitespace-only changes don't trigger downstream content-hash invalidations, so CDN cache keys and CI cache layers stay warm. Real changes get all the rebuild budget.

review-ready

Docs examples

Standardise .proto examples for API docs. Pairs with linters (ESLint, Stylelint, pylint) that catch what formatting alone can't — bugs, unused imports, dead code. Each tool stays in its lane, and the codebase stays clean.

deterministic
FAQ

Frequently asked questions

No — buf format also aligns option blocks and applies lint rules. This tool only handles indent depth.
No. Use buf lint or protoc for type and tag checks.
Yes — field tag numbers are part of the text and are never modified.
Reserved declarations are kept verbatim on their own lines.
No — the formatter runs locally in your browser tab.
Suggest a tool

Something missing?

Tell us what you need. We ship the top requests every two weeks.

Sent straight to the maintainers · no account needed
47 in queue·8 shipped this month
Request queued. Thanks!