YAML Validator

About this tool

Check whether your YAML is valid. It loads a trusted YAML parser to report syntax errors precisely.

Example

Input: name: Al

Output: Valid YAML

Privacy

This tool runs entirely in your browser. Your data is processed locally and never uploaded to a server.

How to use this tool

1. Paste your YAML into the input box.
2. Click validate to check the syntax.
3. Read any error message and compare it with the line number shown.
4. Fix the YAML and run the validator again until it passes.

Step by step, what happens

1. The tool sends your YAML to a trusted parser instead of guessing the result.
2. The parser checks indentation, colons, dashes, quotes, and other YAML syntax rules.
3. If the input is valid, the tool reports success and lets you know the YAML can be parsed.
4. If the input is invalid, the tool shows a clear syntax error with the location and reason.
5. You can edit the text and revalidate to confirm each fix.

Worked example

Here is a simple YAML file for a project with a name and a list of dependencies.

Input: name: demo-app dependencies: - yaml - parser

1. Paste the YAML into the validator and run the check.
2. The parser reads the mapping for name and the list under dependencies.
3. Because the indentation and list syntax are correct, the tool accepts the input.

Tips and common mistakes

• Watch indentation closely, since YAML uses it to show structure.
• Use the same list style consistently, especially with hyphens and nested values.
• If the validator points to a line, check the line above it too because the real mistake is often there.
• Quote values when they contain special characters like colon, hash, or leading spaces.

Frequently asked questions