YAML Formatter & Validator
Beautify, re-indent, and validate YAML. Reports syntax errors with line numbers.
The YAML Formatter beautifies and validates YAML in one step. Paste messy YAML with inconsistent indentation or spacing and get back clean, consistently indented output — or a clear error message with a line number if the YAML is invalid. It parses your document with a real YAML engine, so what it accepts is exactly what a compliant parser accepts.
- ✓Re-indents to a consistent 2 or 4 spaces
- ✓Validates and pinpoints syntax errors by line
- ✓Optional alphabetical key sorting
- ✓100% private — nothing is uploaded
Why YAML Formatting Matters
YAML is indentation-sensitive, so a stray tab or misaligned key can silently change meaning or break a parser. Reformatting through a real YAML engine normalizes indentation, quoting, and flow style, which makes config diffs cleaner and catches mistakes before they reach a CI pipeline or Kubernetes cluster. To convert between formats, see YAML to JSON and JSON to YAML.
How to Use It
- 1Paste YAML with inconsistent indentation, mixed spacing, or unsorted keys.
- 2Click Format to re-indent at 2 or 4 spaces, or Format + sort keys to also alphabetize mapping keys.
- 3If the YAML can't be parsed, the exact error and line number appear instead of a silent failure.
- 4Copy the cleaned output back into your config file, pipeline definition, or manifest.
Common YAML Mistakes This Catches
- ▸Mixed tabs and spaces — YAML forbids tabs for indentation — a stray tab silently breaks parsing in some tools and is flagged here immediately.
- ▸Inconsistent indent width — Mixing 2-space and 4-space indentation in the same file still often parses, but re-indenting to one consistent width prevents future mistakes.
- ▸Wrong list/mapping nesting — A misaligned - list item or key can silently attach to the wrong parent; the parser's error output pinpoints exactly where structure breaks.
- ▸Unquoted special values — Bare yes, no, on, off, and null-like strings are interpreted as booleans/null by YAML 1.1 parsers — validating surfaces this before it causes a config surprise.
Common Uses
- ▸CI/CD pipelines — Tidy GitHub Actions, GitLab CI, or CircleCI files and catch indentation errors before a run fails.
- ▸Kubernetes & Docker Compose — Validate manifests and compose files locally so a typo doesn't break a deploy.
- ▸App configuration — Normalize config files so diffs are minimal and reviews are easy.
- ▸Cleaning pasted YAML — Fix inconsistent indentation from copied snippets in one click.
- ▸Pre-commit sanity checks — Validate a YAML file locally before committing, instead of discovering a syntax error in CI.