YAML Formatter & Validator – Clean YAML Instantly

Paste any YAML and instantly clean it up. Fix indentation, validate syntax, and export production-ready YAML for configs, Docker, and Kubernetes. 100% browser-based and private.

Privacy-first: your YAML never leaves your device. No uploads, no server. 100% client-side.

Format on paste, Ctrl+Enter to format, drag-drop .yaml/.yml/.txt (max 2MB). Autosave to localStorage.

IndentationIndentation:
Ctrl/Cmd + Enter · Runs in your browser
1 lines · 0 chars

Paste YAML and click Format YAML or press Ctrl+Enter. Formatted output will appear here.

YAML Formatting Examples

Badly formatted YAML

name:my-app
version: 1.0.0
env:production
ports:
-8080
-8443

Missing spaces after colons, inconsistent list style.

Correctly formatted output

name: my-app
version: 1.0.0
env: production
ports:
  - 8080
  - 8443

Consistent indentation (2 spaces), spaces after colons.

Kubernetes example

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  key: value

Manifests use 2-space indentation by convention.

Docker Compose example

services:
  web:
    image: nginx:alpine
    ports:
      - "80:80"
  app:
    build: .

Services and keys indented under services.

Why use a YAML formatter?

YAML is used everywhere: Kubernetes manifests, Docker Compose, GitHub Actions, Ansible, and CI/CD configs. Messy indentation or mixed styles make files hard to read and review. A formatter normalizes indentation (2 or 4 spaces), aligns key-value pairs, and keeps list items consistent so your configs are readable and version-control friendly.

This tool runs in your browser—no uploads, no server. Your YAML stays private. Use it alongside our JSON formatter and TOML formatter for a consistent workflow.

Common YAML mistakes

Indentation: YAML uses spaces, not tabs. Inconsistent indent (mixing 2 and 4 spaces) causes parse errors. Missing colons: Keys must be followed by a colon and a space (key: value). Lists: Use a consistent style—either - item with proper indent or inline [a, b]. Quotes: Unclosed or mixed quotes in strings break parsing. The validator highlights the line and column so you can fix quickly.

Use Validate YAML before applying configs to catch these issues in the browser with no upload.

YAML vs JSON

YAML is often used as a more readable alternative to JSON for config files: no quotes on keys, comments allowed, and multi-line strings are easier. Both represent the same tree of data. This tool can Copy as JSON so you can paste YAML-derived data into APIs or tools that expect JSON. Formatting and validation use the same parser logic so behavior is consistent.

For pure JSON workflows, use our JSON formatter; for YAML configs (Kubernetes, Docker, CI/CD), this formatter keeps everything client-side and private.

Kubernetes YAML formatting

Format Kubernetes manifests (Deployments, Services, ConfigMaps, Secrets) with consistent indentation. Paste your YAML and get clean, readable output that follows common style guides. Validation catches indentation and syntax errors before you apply with kubectl.

This YAML formatter online runs entirely in your browser—no uploads, so your cluster configs stay private. For other config formats, try our JSON formatter or TOML formatter.

Docker Compose YAML formatting

Clean up docker-compose.yml and Compose V2 YAML files. Fix indentation for services, volumes, and networks so your file is easy to read and version control.

Validate syntax before running docker compose up to avoid runtime errors.

CI/CD and config YAML

Format GitHub Actions, GitLab CI, CircleCI, and other CI/CD YAML configs. Pretty-print and validate workflow files so they are easier to review and debug. Supports multi-document YAML (documents separated by ---).

Privacy-first browser formatting means your pipelines and secrets never leave your machine. Explore more developer tools for formatting, validation, and encoding.

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Frequently Asked Questions

How do I format YAML?

Paste your YAML into the input box and click 'Format YAML' (or press Ctrl+Enter). The tool uses Prettier's YAML formatter to re-indent and clean up your YAML. You can also drag and drop a .yaml or .yml file.

How does YAML validation work?

Validation uses the same YAML parser as formatting. If there is a syntax error (bad indentation, missing colon, invalid list), you'll see an error message with the line number and a hint. Use 'Scroll to error' to jump to the problem line.

Is my YAML uploaded or stored anywhere?

No. All formatting and validation happen entirely in your browser. Your YAML never leaves your device. Optional autosave uses localStorage on your machine only.

Can I control indentation?

Yes. You can choose 2-space or 4-space indentation so the formatted YAML matches your team's style (e.g. Kubernetes, Docker Compose).

Does this tool support Kubernetes and Docker Compose YAML?

Yes. The formatter works with any valid YAML, including Kubernetes manifests, Docker Compose files, GitHub Actions, and CI/CD configs. Multi-document YAML (documents separated by '---') is supported.