YAML Formatter / Validator
YAML (YAML Ain't Markup Language) is a human-readable data serialization format widely used for configuration files, CI/CD pipelines, Kubernetes manifests, and more. Proper formatting and validation ensure your YAML files are error-free before deployment.
This tool formats, validates, and converts YAML to JSON. It highlights syntax errors with line and column numbers so you can quickly fix issues in your configuration files.
How it works
YAML uses indentation-based structure with key-value pairs, lists (prefixed with -), and nested mappings. Proper indentation (typically 2 spaces) is critical for valid YAML.
Use cases
- Validating Kubernetes manifests and Helm charts
- Formatting CI/CD pipeline configurations (GitHub Actions, GitLab CI)
- Checking Docker Compose files for syntax errors
- Converting YAML configuration to JSON format
Frequently asked questions
How do I validate a YAML file online?
Paste your YAML into the tool and it checks the syntax instantly. If there is an error, it reports the message along with the line and column number so you can jump straight to the problem. Valid YAML can then be reformatted or converted to JSON.
Why does my YAML file have indentation errors?
YAML is indentation-based, so structure comes entirely from consistent spacing — typically 2 spaces per level. Tabs are not allowed for indentation in YAML, and mixing indent widths across sibling keys breaks the mapping structure. Using a formatter normalizes indentation and surfaces the exact line where parsing fails.
How do I convert YAML to JSON?
Paste your YAML into this tool and choose the JSON conversion option — the parsed data structure is re-serialized as JSON. Since YAML represents the same key-value, list, and nested-mapping structures as JSON, the conversion is lossless for standard data. Comments, however, exist only in YAML and are dropped in JSON output.
What is the difference between YAML and JSON?
Both represent structured data, but YAML uses indentation instead of braces and brackets, supports comments (starting with #), and is generally easier for humans to read and edit. JSON is stricter and more widely used for machine-to-machine APIs. YAML dominates configuration files such as Kubernetes manifests, Docker Compose, and CI/CD pipelines.
What is YAML used for?
YAML is the standard format for configuration files across modern infrastructure: Kubernetes manifests, Helm charts, Docker Compose files, and CI/CD pipelines like GitHub Actions and GitLab CI. Its human-readable, indentation-based syntax makes configs easy to write and review. Validating YAML before deployment catches syntax errors that would otherwise fail a pipeline or rollout.