// YAML
YAML tools for developers.
Format, validate, convert, and inspect YAML without leaving your browser. Every tool below processes your data locally — nothing is uploaded.
Format & validate
Pretty-print, normalize, and check YAML syntax with line-aware errors.
Convert
Move between YAML and JSON, or transform YAML into other data formats.
What is YAML?
YAML ("YAML Ain't Markup Language") is a human-readable data serialization format commonly used for configuration files, CI pipelines, and Kubernetes manifests. It uses indentation to express structure and supports maps, sequences, scalars, and anchors. Unlike JSON, YAML allows comments and doesn't require braces or brackets.
Because YAML is whitespace-sensitive, even a single missing space or mixed tab can break a document. The tools above help you catch and fix these issues without leaving your browser. Whether you're writing a docker-compose.yml, a GitHub Actions workflow, or a Kubernetes deployment, these tools handle the common YAML tasks.
Common YAML mistakes.
Mixed indentation. YAML requires consistent indentation — typically 2 spaces. Mixing 2-space and 4-space indentation, or using tabs instead of spaces, will cause parse errors. Use a formatter to normalise indentation automatically.
Missing colons. Every key in a YAML mapping needs a colon separator. Without one, YAML reads the line as a plain scalar and the key is silently ignored. The validator will flag these with the exact line and column.
Unquoted special characters. Values like yes, no, true, and false are interpreted as booleans in YAML. If you want the literal string "yes", wrap it in quotes. The quote converter tool can switch between styles automatically.
YAML use cases.
Kubernetes manifests
Kubernetes resources are defined in YAML files. Our validator checks syntax before you apply manifests to a cluster, and the formatter keeps your configs consistent across teams.
Docker Compose
docker-compose.yml files are YAML. If your Compose file isn't working, use the validator to catch indentation errors, missing colons, or incorrect list syntax before running docker-compose up.
GitHub Actions
GitHub Actions workflows are YAML. When your workflow isn't triggering or is failing silently, paste it into the validator to find syntax issues that GitHub's UI doesn't highlight clearly.
Application config
Many applications use YAML for configuration — Ruby on Rails, Ansible, Helm, and more. Use the converter to switch between YAML and JSON when migrating configs or debugging serialization issues.
The YAML tooling ecosystem.
YAML has become the dominant format for configuration in cloud-native development. Kubernetes, Docker Compose, GitHub Actions, ArgoCD, Flux, Helm, and Ansible all use YAML as their primary configuration format. This widespread adoption means developers need reliable tools to create, validate, and transform YAML files as part of their daily workflow. The tools on this page cover the most common YAML tasks without requiring you to install anything.
Beyond configuration, YAML is increasingly used for data exchange between services, especially in CI/CD pipelines where human readability matters. When debugging a failed pipeline, being able to quickly validate, format, or diff YAML files saves significant time compared to manually scanning hundreds of nested lines for a single indentation error.
For teams working with YAML at scale, establishing consistent formatting conventions is essential. A YAML formatter enforces consistent indentation, quoting rules, and line breaks across all files in a repository. Combined with validation in pre-commit hooks and CI, this creates a safety net that catches errors before they reach production environments.