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About this YAML Formatter Online YAML Formatter & Beautifier

Working with messy `values.yaml`, `docker-compose.yml` or GitHub Actions workflows? This YAML formatter normalizes indentation and line wrapping while preserving anchors, aliases and block scalars. Paste your YAML, tweak indentation settings and copy back clean, review-ready config in seconds. 🚀

Key Features of This YAML Formatter

  • Prettier-based formatting tuned for YAML 1.2 configuration files
  • Consistent indentation with configurable indent size (1–8) and spaces vs tabs
  • Adjustable wrap / line length so long keys and values remain readable
  • Correctly handles anchors, aliases, booleans-as-strings and multiline block scalars
  • Works with `.yaml` and `.yml` files for Kubernetes, Docker Compose, CI pipelines and more
  • Paste YAML from your editor or drag-and-drop config files into the formatter
  • One-click copy of formatted YAML back into your editor or repository
  • Formatting runs primarily client-side in your browser; a secure server fallback may be used only if a required parser/plugin is missing

🔧 How to Format YAML Config Files for yaml-formatter

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1. Paste or Upload Your YAML

Copy any YAML snippet (Kubernetes manifest, `docker-compose.yml`, GitHub Actions workflow, Ansible playbook, etc.) and paste it into the editor, or drag & drop a `.yaml` / `.yml` file.

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2. Tune Indentation and Wrapping

Choose whether to use spaces or tabs, set the indent size (1–8 spaces) and adjust the wrap / line length to match your team’s style. A wrap length of `0` effectively disables wrapping by using a very large internal `printWidth`.

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3. Run the Formatter

Click the **Format** button. The Prettier-based YAML engine rewrites your config with consistent indentation while preserving anchors, aliases and block scalars so semantics don’t change.

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4. Copy the Clean YAML

Review the output, then copy the formatted YAML back into your editor, commit it to Git or paste it into your CI/CD or cloud provider UI.

Technical Specifications

Formatting Engine & YAML Support

This tool is built on top of a Prettier-based YAML formatter with configuration options surfaced in the UI.

FeatureSupportNotes
YAML version✅ YAML 1.2 (typical)Suitable for modern config-style YAML used in Kubernetes, Docker, CI/CD and apps.
Anchors & aliases✅ PreservedKeeps `&anchor` and `*alias` references intact while re-indenting surrounding structure.
Block scalars✅ PreservedMaintains `|` and `>` block scalars with internal indentation respected.
Booleans & numbers✅ Careful handlingFormatting keeps values but may expose differences between `yes` vs "yes" or `0012` vs "0012".
Multi-document YAML (`---`)✅ TypicalMultiple documents in the same file are kept in order and formatted consistently.
If a given YAML snippet uses extremely exotic syntax or custom tags that the bundled Prettier YAML parser does not understand, you may see a parser error. In that case, simplify the snippet or run formatting locally with your own toolchain.

Indentation, Wrap Length & Output Style

The formatter exposes key options so you can match your project’s style as closely as possible.

SettingOptionsPractical Recommendation
Indent styleSpaces / TabsMost YAML style guides recommend spaces; tabs only if your team explicitly prefers them.
Indent size1–8 spaces2 spaces is common for Kubernetes and Docker; 4 spaces for extra visual clarity.
Wrap / line length0–120 columns`0` disables wrapping (uses a very large internal `printWidth`), 80–100 keeps diffs compact.
File extensions.yaml, .ymlMatches the `fileExtensions` and `acceptedFileTypes` in the tool config.
Align these options with your repository’s `.prettierrc` or `.editorconfig` so that online formatting matches local development and CI checks.

Limits & Performance

Optimized for interactive formatting of YAML configs in a browser tab.

ParameterLimit / BehaviorNotes
Max text input size≈ 2 MB (~2,000,000 characters)Safety limit enforced inside the formatter function.
Max file upload size≈ 5 MBBounded by the UI `maxFileSize` setting for convenience and reliability.
Formatting timeout~25 secondsLong-running operations are aborted to prevent the browser from hanging.
Primary executionClient-sideRuns via `runPrettier` and a Prettier YAML plugin directly in your browser.
Server fallbackOn parser/plugin errors onlyIf a required parser plugin is missing, a secure `/api/yaml-formatter` endpoint can be used as a fallback.
For huge YAML bundles (Helm charts, giant CRD libraries, etc.), prefer CLIs like `prettier` or `yq` integrated into your local workflow or CI pipelines.

CLI Alternatives for YAML Formatting

Use the online formatter for quick cleanups, and rely on CLI tools for large projects and automated pipelines.

Linux / 🍏 macOS

Format a YAML file with yq (pretty-print)

yq eval -P config.yaml > config.formatted.yaml

Rewrites YAML with consistent indentation and key ordering depending on the yq version.

Normalize YAML with Prettier

prettier --parser yaml --write "**/*.{yaml,yml}"

Runs the same class of engine (Prettier YAML parser) across your entire repository.

Windows (PowerShell / cmd)

Format YAML using PowerShell + yq

yq eval -P config.yaml | Set-Content config.formatted.yaml

Pretty-prints YAML and writes the result back to disk.

Round-trip YAML via PowerShell objects

Get-Content config.yaml -Raw | ConvertFrom-Yaml | ConvertTo-Yaml | Set-Content config.formatted.yaml

Uses PowerShell’s YAML support to normalize structure and indentation.

Combine this online formatter with a `prettier --check` or `yq` step in your CI pipeline to guarantee that all YAML in the repo remains consistently formatted.

Practical YAML Use Cases

Infrastructure & Kubernetes Manifests

  • Format Kubernetes `Deployment`, `Service` and `Ingress` manifests before code review.
  • Normalize `values.yaml` files in Helm charts to make diffs cleaner.
  • Keep CRDs, ConfigMaps and Secrets YAML consistently indented across environments.
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-app
          image: my-app:latest
          ports:
            - containerPort: 80

Docker Compose & Local Dev Config

  • Beautify `docker-compose.yml` before sharing it in documentation or tickets.
  • Align indentation of services, networks and volumes for easier maintenance.
  • Prepare clean YAML snippets for blog posts and onboarding guides.
version: "3.9"
services:
  web:
    image: myapp:latest
    ports:
      - "8080:80"
    environment:
      - NODE_ENV=production
  db:
    image: postgres:16
    environment:
      POSTGRES_PASSWORD: example

CI/CD Pipelines & Automation

  • Format GitHub Actions workflows (`.github/workflows/*.yml`).
  • Clean up GitLab CI (`.gitlab-ci.yml`) or Azure Pipelines YAML.
  • Keep automation and infra-as-code YAML readable across teams.
name: CI
on:
  push:
    branches: [ main ]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 22
      - run: npm ci
      - run: npm test

❓ Frequently Asked Questions

❓What does this YAML formatter do?

It takes YAML input (typically configuration files) and rewrites it with consistent indentation and wrapping using a Prettier-based YAML engine. The semantics of your config stay the same, but the layout becomes much easier to read and review.

🧩Which YAML features are supported?

The formatter is designed for common YAML 1.2 features used in config files: mappings, lists, anchors and aliases, block scalars (`|` / `>`), and multi-document files separated by `---`. Custom tags and very exotic constructs may not be fully supported by the underlying parser.

📏Is there a size limit for YAML input?

For stability and browser performance, text input is limited to about 2 MB (~2,000,000 characters) and uploaded files to around 5 MB. For larger codebases or generated YAML, run Prettier or yq from your CLI or CI pipeline instead.

🔐Is my YAML uploaded to a server?

Formatting runs primarily in your browser via `runPrettier` and the Prettier YAML plugin, so your YAML does not leave the client in normal operation. In rare cases where a required parser plugin is missing, the tool may fall back to a secure `/api/yaml-formatter` endpoint. Even then, your YAML is only processed transiently and not stored.

⚠️Why do I sometimes see parser errors?

Parser errors usually mean the YAML is malformed (e.g. inconsistent indentation, missing `:` or misaligned list items) or uses syntax the bundled parser does not understand. Validate indentation and structure, or try simplifying the snippet, then run the formatter again.

📚How does this relate to my local Prettier setup?

This tool uses a Prettier-based YAML engine under the hood, similar to running `prettier --parser yaml`. You can use it for quick one-off fixes and still rely on your local `.prettierrc` and CLI commands for full-project formatting.

Pro Tips

Best Practice

Normalize all YAML in a repo (Kubernetes, GitHub Actions, Docker Compose) with the same indentation style to make diffs and reviews much easier.

Best Practice

Be careful with values like `yes`, `no`, `on`, `off`, `0012` – quote them if you want them treated as strings instead of booleans or octal-like numbers.

Best Practice

Use this online formatter to quickly clean up snippets for documentation or tickets, then rely on `prettier` or `yq` in pre-commit hooks for full projects.

CI Tip

When refactoring big configs, format first so that semantic changes stand out clearly in Git diffs instead of being buried in indentation noise.

Additional Resources

YAML 1.2 Specification
Technical specification
Getting Started with YAML
Documentation
Prettier – Code Formatter (YAML Support)
Documentation
YAML Formatting Cheat Sheet
Documentation

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