100% Client-Side

YAML Formatter

Format, validate, and minify YAML — with syntax error detection

Free Client-Side No Login No Storage
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YAML to JSON Converter Convert YAML to JSON — for config files, CI/CD, and API schemas JSON Formatter & Validator Beautify and validate JSON data — with syntax highlighting and error detection

How to Use the YAML Formatter

  1. Paste your YAML.
  2. Choose Format or Minify mode.
  3. Select indent style and click Format.

Parses and re-serializes YAML with proper indentation using js-yaml. Validates syntax and reports errors.

What is YAML Formatting & Linting?

The YAML Formatter is a real-time beautifier and syntax validator for YAML files. Because YAML relies strictly on indentation to define document hierarchy, formatting errors often cause cryptic build failures. This tool cleans inconsistent whitespace, standardizes indentation depth, and validates syntax against the YAML 1.2 specification.

Common Uses

  • Fixing indentation bugs in Kubernetes pod and service manifests
  • Validating GitHub Actions, GitLab CI/CD, and Docker Compose YAML configurations
  • Standardizing 2-space indentation across enterprise infrastructure-as-code files (Ansible)
  • Formatting complex OpenAPI / Swagger API specification documents

Frequently Asked Questions

Why are tabs forbidden in YAML files?

The YAML specification explicitly forbids tab characters (`\t`) for indentation because different editors and terminal pagers interpret tab widths differently. YAML requires spaces to guarantee universal consistency.

How does this formatter identify syntax errors?

The formatter parses the document using an AST parser, instantly reporting the exact line number, column, and description of any structural indentation or syntax error.

Does formatting YAML alter multiline string blocks (`|` and `>`)?

No. Literal multiline blocks (`|`) and folded multiline blocks (`>`) are preserved with their exact internal whitespace intact.

Notes from this implementation

Indent with spaces, keep the comments if you can

The formatter reprints YAML with a consistent indent. Tabs are not indentation in YAML. A file that “looks aligned” with tabs will parse as a broken structure or as a different structure. This is the page to use when you want the manifest readable and you need the comments. The YAML/JSON converter drops comments because JSON has nowhere to put them.

Unquoted values such as NO, country codes, and version strings like 1.0 can change type under YAML 1.1 rules. After formatting, scan for booleans you did not intend. Quote them if they must stay strings.