YAML Formatter & Validator

Indentation

Sort keys

Input

Output

Output: lines

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 >).

Format and normalize YAML

The YAML formatter brings YAML files into a consistent, correctly indented shape and checks them for syntax errors. Because YAML derives its meaning purely from indentation, that is exactly what makes it error-prone – a single misplaced space can render an entire configuration unusable. The tool helps when working with CI pipelines, Kubernetes manifests or app configurations and runs entirely in the browser.

Common use cases

CI/CD pipelines: Check and format GitHub Actions or GitLab CI files before broken YAML stops your build.
Kubernetes manifests: Bring deployment or service definitions into clean, consistent indentation.
App configuration: Edit configuration files and make sure the structure stays valid.
Fix indentation: Normalize mixed tabs and spaces, which YAML is especially prone to mishandling.

How to format your YAML

1 Paste your YAML into the input field.
2 The tool checks the syntax and normalizes the indentation.
3 Review any reported errors and fix them.
4 Copy the clean YAML into your file.

Why YAML is so finicky

YAML is friendly to read but sensitive to indentation, tabs and special characters. Even one misplaced space changes the nesting and therefore the meaning. A formatter makes this structure visible and reports violations early – which saves frustrating debugging in pipelines. Use spaces consistently instead of tabs, as that is the most common source of errors. Because nothing is uploaded, even configurations containing credentials stay safe.

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