YAML formatting
Formatting normalizes indentation and spacing from parsed YAML documents while keeping YAML output as YAML instead of changing it into JSON or another format.
YAML Formatter
Format YAML into clean, readable configuration files with syntax validation and helpful error messages.
Paste YAML content or load a sample to begin.
YAML input
Paste Kubernetes, GitHub Actions, Docker Compose, OpenAPI, or other YAML configuration text.
Formatted YAML
Formatted YAML appears after validation.
YAML validation
Syntax, documents, and formatting report
Validate YAML to see document counts, mappings, sequences, syntax errors, warnings, and formatted output.
YAML Guide
Format configuration YAML without converting it
YAML is used across infrastructure, CI/CD, application settings, API descriptions, and local development workflows.
YAML syntax
The validator checks mappings, sequences, anchors, aliases, merge keys, multiline strings, folded scalars, block scalars, and multiple documents.
Formatter vs converter
A YAML Formatter cleans and validates YAML configuration text. A YAML Converter changes the data into JSON or another representation, which can lose YAML-specific syntax.
Anchors and aliases
Anchors, aliases, and merge keys are useful for repeated configuration. Review warnings because downstream tools may interpret merged values differently.
Multiline strings
Block scalars and folded scalars are common for scripts, certificates, release notes, and embedded configuration. Formatting preserves YAML text structure where supported.
Common mistakes
Mixed indentation, missing spaces after colons, tabs, duplicate keys, misplaced sequence dashes, and unclosed quotes are frequent YAML syntax problems.
YAML Formatter FAQ
Does this run YAML tags, scripts, templates, or references?
No. YAML is treated as configuration text only. The tool does not execute tags, scripts, templates, commands, or external references.
Does it support multiple YAML documents?
Yes. Multiple documents are parsed, validated, and formatted with document separators preserved where the YAML library supports them.
Are comments preserved?
Comments are preserved where the YAML parser can attach them to the document. Review formatted output before replacing hand-edited configuration files.
Why warn about duplicate keys?
Duplicate YAML keys are risky because consumers may keep the first value, keep the last value, or reject the file entirely.
Is this different from YAML to JSON?
Yes. YAML Formatter keeps YAML as YAML. YAML to JSON converts the parsed YAML data into JSON and may lose comments, aliases, document markers, and YAML-specific style.