Toolkernel
  • CSV
  • JSON
  • Regex
  • PDF
  • JWT
  • YAML
  • Cron
Toolkernel

Free, privacy-focused developer tools that run entirely in your browser.

  • ✓ 100% browser-based
  • ✓ No data uploaded
  • ✓ Free forever

JSON & CSV

  • JSON Formatter
  • JSON Compare
  • JSON Auto-Fix
  • CSV Cleaner & Merger
  • YAML Formatter

PDF Tools

  • Merge PDF
  • Split PDF
  • Compress PDF
  • PDF to Images
  • All PDF Tools

More Tools

  • Regex Tester
  • JWT Decoder
  • Cron Builder

© 2026 Toolkernel. All rights reserved.

Your files never leave your device. Built for developers who value privacy.

  1. Toolkernel
  2. /
  3. YAML Tools
Your config files stay private

Format & ConvertYAML Instantly

Beautify YAML configs, convert between YAML and JSON, compare files, and validate syntax. Perfect for Kubernetes, Docker Compose, and CI/CD workflows.

Free forever. No signup required. Works offline.

YAML Formatter

Format, validate, convert, and compare YAML documents with customizable options

Open Formatter
Format & Beautify
YAML ↔ JSON
Validate Syntax
Compare Files
100%
Browser-based
0
Data uploaded
∞
Files processed

What is YAML?

YAML (YAML Ain't Markup Language) is a human-readable data serialization format commonly used for configuration files. Unlike JSON, YAML uses indentation for structure, supports comments, and is designed for easy reading and writing by humans.

YAML has become the de-facto standard for DevOps configuration. It's used in Kubernetes manifests,Docker Compose files, GitHub Actions workflows, Ansible playbooks,GitLab CI pipelines, and countless other tools. Understanding YAML is essential for modern infrastructure and deployment workflows.

YAML Syntax Example

# This is a comment
apiVersion: v1
kind: Service
metadata:
  name: my-service
  labels:
    app: web
spec:
  ports:
    - port: 80
      targetPort: 8080
  selector:
    app: web

Kubernetes

Deployments, Services, ConfigMaps, Secrets, Ingress, and all K8s resource definitions use YAML.

Docker Compose

Multi-container Docker applications, service definitions, networks, and volumes.

CI/CD Pipelines

GitHub Actions, GitLab CI, CircleCI, Azure Pipelines, and other workflow definitions.

YAML vs JSON Comparison

YAML is a superset of JSON—any valid JSON is also valid YAML. However, YAML offers additional features that make it better suited for configuration files.

FeatureYAMLJSON
ReadabilityMore human-readableLess readable (brackets, quotes)
CommentsSupported (#)Not supported
Multi-documentSupported (--- separator)Not supported
Anchors/AliasesSupported (& and *)Not supported
QuotesOptional for most stringsRequired for all strings
API UsageLess commonStandard for REST APIs
Best ForConfiguration filesData exchange

When to Use a YAML Formatter

Standardizing Configs

Ensure consistent indentation and formatting across your team's Kubernetes manifests and config files.

Debugging Syntax Errors

Find and fix YAML parsing errors with clear error messages and line numbers before deployment.

Converting Formats

Convert between YAML and JSON when APIs require different formats or for debugging complex structures.

Reviewing Changes

Compare YAML files to review config changes before deploying to production environments.

Why Privacy Matters for YAML

YAML configuration files often contain sensitive information: database credentials, API keys, encryption secrets, cloud provider tokens, and infrastructure details. Using a server-based YAML formatter means potentially exposing this data to third parties.

Our formatter runs 100% in your browser. Your Kubernetes secrets, Docker credentials, and CI/CD tokens never leave your device. You can verify this by checking your browser's Network tab or even use the tool offline after loading.

GDPR CompliantSafe for SecretsWorks Offline

Frequently Asked Questions

How do I format YAML online?

Paste your YAML into the formatter, choose your indentation (2, 4, or 8 spaces), and click 'Format YAML'. The output appears instantly with proper indentation. All processing happens in your browser.

How do I convert YAML to JSON?

Switch to 'YAML → JSON' mode, paste your YAML, and click 'Convert to JSON'. The tool parses the YAML and outputs equivalent JSON. This is useful for APIs or debugging.

Is my YAML data uploaded to a server?

No. All processing happens in your browser using JavaScript. Your config files, including secrets and credentials, never leave your device. You can even use it offline.

Why is my YAML showing as invalid?

Common issues: inconsistent indentation (mixing tabs/spaces), missing space after colons, unquoted special characters, or incorrect list formatting. The error message shows the line number to help debug.

Can I format Kubernetes and Docker Compose files?

Yes! Both Kubernetes manifests and Docker Compose files use standard YAML. Paste your config, format it, and copy it back. The formatter preserves all structures.

Related Developer Tools

JSON Formatter

Format and validate JSON data

Cron Builder

Build cron schedules for K8s CronJobs

Regex Tester

Test patterns for config validation