YAML Validator

Validate YAML, spot syntax errors, and convert valid YAML to JSON or normalized YAML.

YAML Validator

Validate YAML syntax and optionally convert to JSON or normalized YAML.

Settings Prefilled examples
Tip: YAML is indentation-sensitive. Use consistent spaces, especially in nested blocks.
Strict mode helps catch ambiguous values early. If a file validates but behaves oddly, try enabling strict mode.
Result Copy-ready
No output yet
Paste YAML and click Generate to validate it.
Copied

About YAML Validator

YAML Validator for Fast YAML Syntax Validation

Validate YAML instantly and catch formatting errors before they break a deployment, pipeline, or configuration file. This online YAML Validator checks your input, highlights common parsing problems, and can also convert valid YAML into readable JSON for quick inspection.

How YAML Validator Works

YAML is sensitive to indentation, quoting, and structure. This tool parses your text with a standards-based YAML parser and returns either a “Valid YAML” confirmation or a detailed error message. When the YAML is valid, you can optionally transform it into a normalized representation (helpful for consistent formatting) or export it to pretty-printed JSON.

Step-by-Step

  • 1) Paste YAML: Add your YAML document into the input box, including lists, maps, multi-line strings, and comments.
  • 2) Choose a mode: Validate only, convert to JSON, or generate normalized YAML output (when supported).
  • 3) Enable strict parsing: Strict mode helps surface ambiguous constructs and unexpected scalar types early.
  • 4) Generate results: The validator returns a clear status and, on errors, a message that typically includes the line where parsing failed.
  • 5) Copy or download: Copy the output to your clipboard or download it as a plain text file for sharing in reviews or tickets.

Key Features

Accurate YAML Syntax Checking

The validator checks indentation, list markers, mapping keys, quoting rules, and document structure. It is designed to catch the issues that commonly slip into CI/CD files, Kubernetes manifests, Docker Compose configs, GitHub Actions workflows, and application settings.

Helpful Error Messages

When your YAML is invalid, the tool reports a human-readable message. Many parsers can point to the parsed line or nearby location so you can jump directly to the problematic block and fix the root cause rather than guessing.

Convert YAML to JSON

Converting valid YAML to JSON is useful when you want to quickly confirm the final data structure (especially with anchors, nested maps, and lists). The JSON output is pretty-printed so you can visually verify keys, arrays, and values.

Normalized YAML Output

For teams that prefer consistent formatting, normalized YAML output provides a clean dump of the parsed data. This can reduce noise in pull requests by eliminating accidental indentation drift and inconsistent quoting styles.

Private, One-Page Workflow

Everything happens in a single page: paste, validate, copy. The interface includes a clear empty state, a processing spinner, and convenient copy/download actions so you can validate snippets during reviews without switching tools.

Use Cases

  • CI/CD pipelines: Validate YAML used by GitHub Actions, GitLab CI, Azure DevOps, or other pipeline engines before committing.
  • Kubernetes manifests: Catch indentation and list errors that can block apply/upgrade operations or produce unexpected objects.
  • Docker Compose files: Confirm service definitions, networks, volumes, and environment blocks parse correctly.
  • App configuration: Validate settings files for frameworks and libraries that accept YAML configuration.
  • Infrastructure as Code: Verify YAML used for Helm values, cloud templates, and environment overlays.
  • Documentation snippets: Ensure examples in READMEs and internal docs are correct and copy-paste ready.
  • Debugging parser issues: Quickly isolate the minimal failing snippet by iterating and validating as you simplify a file.

Whether you maintain production infrastructure or write internal documentation, a quick YAML validation step prevents avoidable downtime and reduces time spent chasing “did I miss a space?” errors.

Optimization Tips

Use Spaces, Not Tabs

Most YAML style guides recommend spaces only, and many parsers treat tabs as invalid indentation. If you see confusing structural errors, replace tabs with spaces and keep indentation consistent within each block.

Quote Ambiguous Strings

YAML has implicit typing for booleans, nulls, and numbers. If a value like on, off, yes, or a leading-zero number is meant to be a string, quote it to avoid type surprises in downstream tools.

Validate After Refactors

Small edits like moving a list item or changing a nested map often introduce indentation errors. Validate immediately after refactors, especially when editing large manifests or complex pipeline steps.

FAQ

A YAML validator checks that your document can be parsed according to YAML rules: indentation, list and map structure, quoting, and scalar formatting. If parsing fails, it returns an error describing what went wrong.

YAML uses indentation to represent nesting. A single extra or missing space can change a map into a list, move a key under the wrong parent, or cause a parser error. Consistent spacing keeps the structure unambiguous.

Yes. If your YAML is valid, you can switch the output mode to JSON to see the parsed data structure as pretty-printed JSON. This is useful for verifying nested arrays and objects at a glance.

Strict mode is intended to surface questionable constructs earlier, such as unexpected scalar types or values that can be interpreted in surprising ways. It is especially helpful when YAML will be consumed by tools with strict schemas.

The addon prefers the Symfony YAML component and can also use the PHP ext-yaml extension when installed. If neither exists, the tool will show a clear message explaining that a YAML parser is not available on the server.

Why Choose YAML Validator?

YAML is easy to read but easy to break. A quick validation step prevents configuration errors from reaching production and saves time during reviews. This tool focuses on speed and clarity: paste your file, get a decisive answer, and move on.

Because the validator can also produce JSON and normalized output, it fits naturally into debugging and collaboration workflows. Validate snippets in tickets, share copy-ready outputs, and keep your configs consistent across environments.