YAML FORMATTER / VALIDATE

YAML Formatter

Aligned indentation with comments kept; no more configs broken by one space.

Runs locally · code is not uploaded
Options

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How to use it

  1. Paste code, drop a file or load the sample; the language is preset for this page and can be changed.
  2. Choose format or minify and adjust indent, width and other options; the result appears on the right as you type.
  3. Copy or download the result; on an error, use "Go to error", fix it and run again.

Languages and engines

Formatting uses the same open-source engines as popular editors, so results match Prettier in VS Code and your team can keep one style. Every engine loads from this site and runs in your browser.

Language
LanguageFormatCompress
HTMLPrettier 3✓ comments and whitespace
XMLXunL XML engine✓
CSS / SCSS / LessPrettier 3✓ CSSO restructuring
JavaScript / TypeScriptPrettier 3(Babel)✓ Terser (JavaScript only)
JSONPrettier 3✓ big numbers keep precision
YAMLPrettier 3— (comments kept)
SQLsql-formatter (14 dialects)—

Frequently asked questions

What are the most common YAML errors?

Tab indentation (YAML allows only spaces), inconsistent indentation at one level, no space after a colon, and unquoted strings containing a colon or #. Failures show the line and column.

Is my code uploaded?

No. The engines download from this site and run in your browser; your code never passes through our servers or any third party, so it is safe for internal code and configuration.

How large can files be?

Up to 5 MB per file; above 300 KB the page waits for the button instead of formatting as you type, to keep the browser responsive.

YAML formatter practical guide and common questions

What does a YAML formatter do?

Prettier 3's YAML parser normalises indentation to spaces and tidies lists and maps, keeping comments and --- document separators.

Who is this for, and when is it useful?

Developers and operators writing Docker Compose, Kubernetes, GitHub Actions and application configuration who are chasing indentation errors.

How do I use this YAML formatter?

Paste YAML for consistent indentation with comments kept, and syntax errors with line and column.

How should I interpret the results?

YAML forbids tab indentation; anchors, aliases and block strings are preserved, but fields are not checked against schemas such as Kubernetes.

Where is the work performed, and which services receive data?

YAML is formatted in your browser, so passwords and keys in it are never uploaded.