⌘ K
ruby · keyword-tracked · indent · live

Format Ruby source

Tracks def/class/do/if/case openers and end closers to compute indent. Use RuboCop for real Ruby formatting. Runs locally.

Ruby Formatter
Input
59 B
5 lines
Output
68 B
6 lines
Status
ready
live
Ratio
1.15×
out/in
input · ruby
output · formatted ruby
class Greeter
  def greet(name)
    puts "Hello, #{name}"
  end
end
Quick Start

How to format Ruby

A keyword-tracking indenter — def/class/if/do open new levels, end / else / when close or continue.

  1. 01

    Paste your code

    A method, a class, or a quick irb snippet. The formatter normalises each line.

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

    rubyPrettierASTstandalonelazy
    input · sourceraw · AST
    def m;1;end
    loaded · parsedAST · ready
  2. 02

    Set indent width

    2 spaces is the Ruby community default. RuboCop expects this too.

    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=2
    options applied · livelive
  3. 03

    Watch blocks align

    def/class push depth, end pops it. else / elsif / when / rescue pull back to match their opener.

    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
    class A
  def m
    1
  end
end
    formatted · liveidempotent
  4. 04

    Copy or download

    Save as .rb 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.

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Use Cases

When to format Ruby

Rails edits, snippet cleanup, code reviews.

Rails edits

Re-indent a controller method after a quick change. 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

Snippet cleanup

Tidy a tutorial paste before saving to a gem. 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

Code reviews

Strip whitespace churn so diffs show real changes. 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

Rake tasks

Reformat lib/tasks .rake files after edits. 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

irb saves

Tidy code copied from an irb session. 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 Ruby examples for documentation. 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 — it is a heuristic keyword indenter. RuboCop checks style and applies many more rules.
No. <<~HEREDOC bodies are not detected and may indent oddly.
No. end stays on its own line; only indentation changes.
Yes — #{...} inside strings is left untouched as it lives on the same line.
No — the formatter runs locally in your browser tab.
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