YAML Formatter Online — Beautify and Validate YAML
Convert JSON to YAML instantly — indent · quote style · flow mode · null/bool style · syntax highlight · 100% Free
app: name: CalcNation version: 3.0.0 debug: false features: - calculator - converter
YAML is sensitive to indentation — a single misaligned space causes parse errors. This YAML formatter validates your YAML syntax, corrects indentation issues, normalizes spacing and produces clean, consistently formatted output. Paste your YAML config, playbook or manifest and get production-ready formatted YAML with error highlighting.
What is JSON to YAML Conversion?
YAML (YAML Ain't Markup Language) is a human-readable serialisation format widely used in configuration files — Docker Compose, Kubernetes, GitHub Actions, Ansible, and CI/CD pipelines. This tool converts any valid JSON to clean, formatted YAML instantly, with full control over indentation, quoting, null representation, boolean style, and flow style for compact output.
YAML vs JSON — When to Use Which
JSON is ideal for APIs and data exchange — strict syntax, universally supported. YAML is preferred for configuration files — more readable, supports comments, and allows multi-line strings. Use this converter when your tooling expects YAML input (Helm charts, k8s manifests, docker-compose.yml) but your data starts as JSON.
Frequently Asked Questions
What are the most common YAML formatting errors?
YAML errors: (1) Tab characters — YAML forbids tabs, use spaces only. (2) Inconsistent indentation — mixing 2-space and 4-space. (3) Missing space after colon — key:value should be key: value. (4) Unquoted special characters — if value contains : or # or starts with {, quote it. (5) Duplicate keys — YAML allows but parsers vary in handling.
Should I use 2-space or 4-space indentation in YAML?
2-space indentation is the standard for YAML config files (Kubernetes, Docker Compose, Ansible all use 2-space). 4-space is also valid but less common. The important rule: be consistent throughout the file. Mix indentation levels only when required by YAML block structure, never within the same mapping level.
How do I validate YAML in CI/CD pipelines?
yamllint: fast, configurable YAML linter. pip install yamllint; yamllint -c .yamllint config.yaml. Schema-specific: kubeval for Kubernetes YAML, ansible-lint for Ansible playbooks, docker compose config for Compose files. GitHub Actions: use Super-Linter action which includes yamllint. Add these to pre-commit hooks for local validation before push.
What is the difference between YAML block and flow style?
Block style: uses newlines and indentation (standard, readable): key: sub: value. Flow style: uses {} and [] (compact, like JSON): {key: {sub: value}}. Block is preferred for configs (readable). Flow is used for short inline structures. This formatter converts to block style — if you need flow style, use JSON instead.