JSON To YAML Converter - Free Online Transformer Easily Convert JSON Code to YAML Code

What Is YAML?

YAML ("YAML Ain't Markup Language") is a human-readable data serialization format defined by the YAML 1.2.2 Specification. It uses indentation to represent nesting, making it more readable than JSON or XML for configuration files. YAML supports scalars (strings, numbers, booleans, null), sequences (lists), and mappings (key-value pairs).  

YAML 1.2 is a strict superset of JSON: every valid JSON document is also valid YAML. This means JSON-to-YAML conversion is lossless — no data is lost or transformed. The reverse is not always true, since YAML supports features JSON does not (anchors, tags, multi-line strings, comments).  

JSON vs YAML: Key Differences

Why Convert JSON to YAML?

• Docker Compose — Convert JSON configuration to docker-compose.yml format

• Kubernetes — Transform JSON manifests to YAML for K8s resource definitions

• CI/CD pipelines — GitHub Actions, GitLab CI, and CircleCI use YAML for workflow definitions

• Ansible playbooks — Convert JSON task definitions to YAML playbooks

• OpenAPI / Swagger — API specifications can be written in YAML for readability

• Application config — Many frameworks (Rails, Spring, Hugo) use YAML for settings

• Human review — YAML's indentation-based syntax is easier to read and edit by hand

About This JSON to YAML Converter

This tool runs entirely in your browser. Your data is never uploaded to any server. No data is transmitted, logged, or stored. The conversion happens locally on your device using JavaScript.  

The tool includes a JSON code editor with syntax highlighting and real-time JSON validation. A green indicator confirms valid JSON; orange flags errors before conversion.  

YAML Output Styles

Block Style (Default)

Block style uses indentation and hyphens to represent structure. Each list item appears on its own line with a - prefix. This is the most common YAML style and the most readable.  

employees:
 - name: Alice
   age: 30
   city: New York
 - name: Bob
   age: 25
   city: London

Flow Style

Flow style uses inline brackets [...] and braces {...} — similar to JSON syntax but without quoted keys. This produces more compact output.  

employees: [
   {name: Alice, age: 30, city: "New York"},
   {name: Bob, age: 25, city: London}
]

Use block style for configuration files and human editing. Use flow style for compact output or when YAML is consumed programmatically.  

How JSON Maps to YAML

Since YAML 1.2 is a superset of JSON, the mapping is direct:  

• JSON objects {"key":"value"} → YAML mappings key: value

• JSON arrays [1, 2, 3] → YAML sequences with hyphen prefixes

• JSON strings "hello" → YAML unquoted strings hello (or quoted if ambiguous)

• JSON numbers 42 → YAML integers 42

• JSON booleans true/false → YAML booleans true/false

• JSON null → YAML null or ~

How to Use This JSON To YAML Converter?

Step 1: Provide JSON Data

Paste your JSON into the code editor, or drag and drop a .json file onto the upload area. Click Sample to load test data. The tool validates the JSON in real time — a green indicator confirms valid input.  

Step 2: Configure Output Options

In the Properties panel:  

• Array Style — Block (one item per line, readable) or Flow (inline, compact)

• Indent Size — 2 spaces (standard for most YAML ecosystems), 4 spaces, or 8 spaces

Step 3: Convert and Export

Click Convert. The YAML output appears in the Output Data panel. Click Copy to Clipboard to copy the result, or Download File (Premium) to save it as a .yaml file.  

Choosing the Right Indent Size

The YAML specification does not mandate a specific indent size — any consistent number of spaces works. Common conventions:  

• 2 spaces — Default for Docker Compose, Kubernetes, GitHub Actions, and most YAML ecosystems

• 4 spaces — Used in some Python-related configs and deeply nested structures

• 8 spaces — Rare; only for very deeply nested data where extra indentation aids readability

YAML does not allow tabs for indentation. This tool uses spaces only.  

Frequently Asked Questions (FAQ)

• Is my data be uploaded or stored on any server?

  All processing happens locally in your browser. Your files are never uploaded, transferred, or stored on any server. The tool works offline after the page loads.  

• Is YAML a superset of JSON?

  Yes. YAML 1.2 (the current specification) is a strict superset of JSON. Any valid JSON document is also valid YAML, so conversion is lossless.  

• What is the difference between block and flow style?

  Block style uses indentation and hyphens — each array item on its own line. Flow style uses inline brackets [...] and braces {...}, similar to JSON. Block style is more readable and standard for configuration files. Flow style is more compact.  

• What is YAML used for?

  YAML is the standard format for Docker Compose files, Kubernetes manifests, CI/CD pipeline definitions (GitHub Actions, GitLab CI), Ansible playbooks, OpenAPI specifications, and application configuration files.  

• Can I convert YAML back to JSON?

  This tool converts in one direction: JSON to YAML. For the reverse, use the YAML To JSON Converter on A.Tools.  

• Why is the Convert button disabled?

  The button is disabled when the input JSON is invalid. Fix syntax errors (missing brackets, trailing commas, unquoted strings) until the validation indicator turns green.  

• Does YAML support comments?

  Yes, using #. JSON does not support comments, so comments cannot appear in the converted output. Add comments manually after conversion.  

• What is the maximum input size?

  There is no server-side limit. Processing happens in your browser, so practical limits depend on your device's available memory. JSON data up to 50 MB typically converts without issue on modern hardware.