YAML Formatter & Validator
Format and normalize YAML files instantly in your browser
Instant YAML formatting
Normalize indentation, fix mixed spaces/tabs, and sort top-level keys in your YAML files. Ideal for Docker Compose, GitHub Actions, Kubernetes and Ansible playbooks.
Built for CI/CD workflows
YAML is the backbone of modern DevOps tooling. Format your GitHub Actions, GitLab CI, CircleCI, and Kubernetes manifests with consistent indentation that parsers can actually read.
No data leaves your browser
All processing happens client-side in JavaScript. Your YAML configuration files — including secrets, tokens and credentials — are never sent to a server.
Frequently asked questions about YAML formatting
YAML syntax rules, best practices and common pitfalls
YAML is a superset of JSON — every valid JSON file is also valid YAML. The key differences are that YAML uses indentation instead of braces, supports comments (# prefixed lines), has a more human-friendly syntax for strings (no mandatory quotes), and supports multi-line strings natively. JSON is better for machine-to-machine communication; YAML is better for human-authored configuration files.
Unlike most programming languages, YAML uses whitespace indentation to define structure — similar to Python. Inconsistent indentation (mixing tabs and spaces, or using 2 spaces in one block and 4 in another) causes parse errors or silently changes the meaning of your document. This is why formatting tools that normalize indentation are so valuable: one wrong space can break an entire CI/CD pipeline.
YAML became the standard for CI/CD configuration because it is human-readable, supports comments, and handles complex nested structures compactly. Tools like GitHub Actions, GitLab CI, CircleCI, Jenkins, Kubernetes, Helm, Ansible, and Docker Compose all use YAML. Its readability makes it easy to review changes in pull requests, which matters in teams practicing GitOps.
The most common YAML errors are: (1) Mixing tabs and spaces — YAML requires spaces only, never tabs for indentation. (2) Off-by-one indentation causing keys to nest incorrectly. (3) Unquoted special values like "yes", "no", "true", "null" being interpreted as booleans/null. (4) Forgetting the colon-space separator (key: value, not key:value). (5) Multi-line strings breaking due to wrong block scalar style (| vs >).