YAML Formatter and Validator: Fix Indentation Online

Paste YAML to check it and re-indent it cleanly. Errors show what is wrong and where. Good for Docker Compose, Kubernetes and CI files. Runs in your browser.

Paste your YAML and press Beautify. The file is re-indented with the spacing you choose, and a syntax error is reported with its place. It works well for Docker Compose, Kubernetes, GitHub Actions and similar files.

What it does

• Re-indents nested keys and list items.
• Checks the YAML and reports the first error.
• Keeps your comments.
• Does not change values or key order.

Example

services:
    web:
        image:   nginx:alpine
        ports: ["8080:80"]
        environment:
          - MODE=dev
          - DEBUG=false

services:
  web:
    image: nginx:alpine
    ports: ["8080:80"]
    environment:
      - MODE=dev
      - DEBUG=false

Frequently asked questions

Why does YAML fail with tabs?

YAML does not allow tabs for indentation. Use spaces. The formatter shows an error if it finds a tab.

Does it keep comments?

Yes.

Can it check Docker Compose files?

It checks that the YAML is valid. It does not know the Compose rules, so a valid file can still contain a wrong key.

Does it handle several documents in one file?

Yes. Documents separated by --- are formatted one by one.

Runs in your browser. Nothing you type is sent to this site. Updated 2026-10-11.

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