YAML validator for Next.js workflows. In your browser.
Validate and format YAML with line and column diagnostics. Review GitHub Actions and Docker Compose configuration without uploads — free, no sign-up.
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YAML syntax, not application-schema validation. One document, 200 KB, nesting 100 and bounded aliases. Comments and anchors are preserved.
How to use
- Paste a single YAML document under 200 KB, such as a workflow or Compose file.
- Choose two or four spaces and Validate and format YAML. Correct any reported line and column.
- Copy or download the formatted YAML. Review the target application's schema and test it in your own environment.
Reference documentation
Frequently asked questions
Is this free, and does my input leave the browser?
Free, no sign-up. Computation, copy and downloads stay in your browser. There is no upload or processing endpoint. Usage analytics include only a fixed tool name and action, never your input or result.
Which YAML version does this validate?
YAML 1.2 with the core schema. A syntax pass does not mean GitHub Actions, Docker Compose or another application accepts the document. JSON is also valid YAML, but only one document is accepted.
Where is the error shown?
Parser diagnostics identify the source line and column. Duplicate keys, invalid indentation, unclosed collections and unsupported tags are reported before a formatted result is shown. Resource-limit errors can describe the whole document.
Does formatting preserve comments and anchors?
Yes. Formatting uses the parsed document tree rather than JSON. Comments, anchors and aliases are retained. Alias expansion is checked with a limit of 50; nesting is limited to 100 levels.
Does this validate Supabase config.toml?
No. Supabase CLI configuration is TOML, not YAML. Use this for YAML workflow and infrastructure files in your Next.js or Supabase project, not TOML validation.
Are numbers and custom tags changed?
Integer parsing uses BigInt internally; formatting preserves YAML nodes without a JSON number round-trip. Unsupported custom tags are reported and quoted strings remain strings.
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