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YAML to JSON Converter — Convert YAML to JSON Online Free [2026]

Convert YAML to JSON instantly online. Paste YAML and get formatted JSON output with syntax validation and pretty-print options. Free online YAML converter.

What is YAML to JSON Converter?

YAML (YAML Ain't Markup Language) is a human-readable data serialization format widely used in configuration files — Docker Compose, Kubernetes manifests, GitHub Actions workflows, and Ansible playbooks all use YAML. Its indentation-based structure and minimal punctuation make it easy to read and write. JSON (JavaScript Object Notation) is the dominant format for data exchange between web services and APIs. It uses curly braces, brackets, and explicit quoting, making it strict and unambiguous but more verbose than YAML. Converting YAML to JSON is a frequent need for developers who work across both ecosystems — for example, taking a Kubernetes config and converting it to JSON for an API call, or transforming a YAML-based fixture into JSON for a test suite. This tool performs that conversion instantly with full support for common YAML types.

How to Use YAML to JSON Converter

Paste your YAML text into the left input panel. Click "Convert to JSON" to transform it into formatted JSON. The result appears in the right panel. Use "Format JSON" to pretty-print an already-converted result. Click "Copy" to copy the JSON to your clipboard, or "Clear" to reset both panels.

How YAML to JSON Converter Works

The converter implements a YAML parser from scratch in TypeScript that handles common YAML patterns: 1. **Comment stripping:** Lines starting with # (after trimming) are ignored. 2. **Scalar parsing:** Values are detected as integers, floats, booleans (true/false/yes/no/on/off), null (null/~/empty), or strings. Quoted strings (single or double) are preserved as-is. 3. **Sequence parsing:** Lines starting with "- " are collected into JavaScript arrays. 4. **Mapping parsing:** Lines with "key: value" pairs are collected into JavaScript objects. Indentation determines nesting level. 5. **Nested structures:** Indentation changes create nested arrays and objects recursively. The parsed JavaScript object is then serialized to JSON using JSON.stringify() with 2-space indentation for readability. All processing happens in your browser — no data is sent to any server.

Common Use Cases

  • Converting Kubernetes YAML manifests to JSON for API requests and tooling
  • Transforming Docker Compose files to JSON for processing with CLI tools and scripts
  • Converting GitHub Actions workflow YAML to JSON for programmatic analysis
  • Migrating configuration from YAML files to JSON-based systems and databases
  • Transforming Ansible variable files from YAML to JSON for REST API consumption
  • Debugging YAML by converting to JSON to verify the parsed data structure

Frequently Asked Questions

What YAML features does this converter support?

This converter handles the most common YAML patterns: scalar values (strings, numbers, booleans, null), mappings (key-value pairs), sequences (arrays with - prefix), nested structures using indentation, and single/double quoted strings. YAML comments (#) are stripped. Advanced features like anchors (&), aliases (*), multi-line strings (| and >), and YAML directives are not supported.

What is the difference between YAML and JSON?

YAML uses indentation for structure and supports comments, making it more human-readable. JSON uses explicit braces, brackets, and commas with no comment support, making it strict and unambiguous. Both represent the same data types (strings, numbers, booleans, null, arrays, objects). YAML is preferred for config files; JSON is preferred for APIs and data interchange.

Why would I convert YAML to JSON?

Many tools and APIs require JSON input but configuration is maintained in YAML. Common scenarios: converting Kubernetes or Docker configs for API calls, transforming YAML fixtures into JSON test data, processing YAML configuration with JSON-only tools, or migrating from a YAML-based system to a JSON-based one.

Does YAML support all JSON data types?

Yes. YAML is a superset of JSON, meaning every JSON document is valid YAML. YAML additionally supports features not in JSON like comments, anchors/aliases, and multi-line block strings. All JSON types (string, number, boolean, null, array, object) have direct YAML equivalents.

What are YAML booleans? How does this tool handle them?

YAML has multiple representations for boolean values: true, false (standard), yes, no, on, off (alternate forms). This converter maps all of these to JSON true or false. For example, YAML "enabled: yes" becomes JSON {"enabled": true}. This matches standard YAML 1.1 behavior used in most configuration tools.

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