YAML Validator
ValidatorsValidate YAML syntax and structure
Common YAML Issues
- Tab indentation — YAML requires spaces, not tabs
- Inconsistent indentation — All items at the same level must use the same number of spaces
- Missing space after colon —
key:valueis a string, not a mapping — usekey: value - Unquoted special characters — Values with
: # [ ] , & * ? | - < > = ! % @ `may need quoting - Boolean gotchas —
yes/no/on/offare parsed as booleans in YAML 1.1
How to Use This Tool
Paste your content
Paste the YAML content you want to validate into the input panel.
See validation results
The validator checks your input in real time and reports whether it is valid or lists specific errors.
Fix errors
Review any error messages shown, which include the line number and a description of the problem.
Confirm valid input
Once the validator shows a success message, your content is confirmed to be valid and well-formed.
About This Tool
YAML Validator is a free, instant, browser-based tool that validate yaml syntax and structure. Validation is a critical step before deploying, processing, or sharing structured data. Invalid JSON causes API errors. Malformed XML breaks parsers. Invalid email addresses bounce. A quick validation check can catch subtle errors — a missing comma, an unclosed tag, an invalid character — that would otherwise surface as cryptic runtime failures.
This tool runs entirely in your browser. Your data is never sent to a server, so you can safely validate sensitive payloads, configuration files, and private data.
Validators are especially useful when you're hand-editing configuration files, constructing API payloads manually, debugging data pipeline errors, or reviewing user-submitted content. They provide immediate, specific feedback: not just "invalid" but exactly which line and character caused the problem, and what the parser expected.
Building validation into your workflow — even informally, by pasting data into a validator before use — prevents a class of bugs that are particularly frustrating to debug because they produce no error until runtime, often in production.
Related Tools
JSON Validator
Validate JSON syntax and report errors with line numbers
XML Validator
Validate XML documents for well-formedness
HTML Validator
Validate HTML markup for errors and warnings
CSS Validator
Validate CSS stylesheets for syntax errors
Email Validator
Validate email address format and syntax
URL Validator
Validate URLs for correct format and structure