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YAML Validator

Validate YAML formatting rules.

Use the tool

Use YAML Validator to catch syntax and indentation issues before a configuration file breaks deployment, automation, or CI.

Dev Workbench

YAML Validator

Validate YAML formatting rules.

Input

Result

Run the tool to see output.
Lines: 0Chars: 0

Why use YAML Validator

  • Check Kubernetes manifests, Docker Compose files, GitHub Actions, and CI configs.
  • Find indentation mistakes, tabs, missing spaces after colons, and broken lists.
  • Validate YAML before converting it to JSON or sharing it in a pull request.
  • Review config snippets that include multiline strings, anchors, aliases, and environment values.

About this tool

YAML validation for config files

YAML Validator checks syntax and indentation so configuration files are less likely to fail when parsed by deployment, automation, and CI tools.

Catch indentation errors early

A single misplaced space can move a key into the wrong object or break parsing. Validation helps catch these problems before kubectl, docker compose, or a pipeline sees the file.

Syntax is not full platform validation

A YAML file can parse correctly and still be invalid for Kubernetes, Docker Compose, GitHub Actions, or another schema. Use platform checks after syntax validation.

Example usage

Input

service:\nname: api

Output

Indentation issue: name should be nested under service when that is the intended structure.

Practical guide for YAML Validator

Best practices

  • Validate YAML before running deployment, Docker, Ansible, or CI commands.
  • Use spaces consistently and configure your editor to prevent tab indentation.
  • Run platform-specific schema checks after syntax validation.

Common mistakes

  • Assuming a YAML formatter proves the file is deployable.
  • Mixing tabs and spaces across nested blocks.
  • Leaving boolean-like strings unquoted when the target system expects text.

How this tool works

  1. Step 1

    Open YAML Validator and review the default example input.

  2. Step 2

    Paste your own input or upload source data when required.

  3. Step 3

    Run YAML Validator to generate output instantly in the browser.

  4. Step 4

    Verify the output using the preview and formatting helpers on the page.

  5. Step 5

    Copy the final result and continue with a related tool if needed.

Use related links to continue your workflow and keep your output consistent across ToolHarbor pages.

JSON FormatterFormat JSON with readable indentation.JSON ValidatorValidate JSON input and return syntax status.XML ValidatorValidate XML syntax and structure.YAML FormatterFormat YAML with normalized spacing.URL Slug ValidatorCheck if text is a valid URL slug.

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FAQ

What does YAML Validator check?

It checks YAML syntax, indentation structure, tabs, lists, mappings, and common parser issues that make a file invalid.

Why are tabs a problem in YAML?

YAML indentation should use spaces. Tabs can make a file fail parsing or behave differently across editors and tools.

Can valid YAML still break Kubernetes or CI?

Yes. Syntax validation only proves the file parses. Platform-specific schemas and required fields still need separate checks.

What YAML mistakes should I look for?

Check tabs, inconsistent indentation, missing spaces after colons, duplicate keys, wrong list levels, and unquoted special values.