YAML Formatter & Validator

Paste YAML or JSON on the left. Format, validate, and convert between YAML and JSON instantly.

🔒100% Client-Side. Everything runs in your browser — no data is sent to any server.

YAML / JSON input

Output

Output will appear here after clicking an action

YAML in Python with PyYAML

import yaml # Parse YAML with open('config.yaml') as f: config = yaml.safe_load(f) # use safe_load, not load() print(config['metadata']['name']) # Write YAML data = {'name': 'my-app', 'replicas': 3, 'ports': [8080, 8443]} with open('output.yaml', 'w') as f: yaml.dump(data, f, default_flow_style=False, indent=2)

YAML vs JSON vs TOML

YAML is popular for configuration files (Kubernetes manifests, GitHub Actions workflows, Docker Compose) because its indentation-based syntax is clean and human-readable with minimal punctuation. JSON is the universal standard for APIs and data interchange — every language has a native parser, and the format is unambiguous. TOML is growing in the developer tooling space (Python's pyproject.toml, Rust's Cargo.toml) because it maps cleanly to hash tables and avoids YAML's indentation pitfalls. The most important YAML gotcha: indentation is significant and tabs are not allowed — mixing tabs and spaces causes cryptic parse errors. Always use 2-space indentation and a YAML linter in CI.