YAML ↔ JSON Converter

What Is YAML and When Should You Use It?

YAML (YAML Ain’t Markup Language) is a human-friendly data serialization format designed to be readable by humans. It uses indentation to express hierarchy and supports comments:

# User profile
name: Alice
age: 30
active: true
address:
  city: New York
  country: USA
tags:
  - developer
  - typescript

YAML is the format of choice for configuration files, CI/CD pipelines, and infrastructure-as-code tools.

Use YAML when:

• Writing configuration files (Docker Compose, Kubernetes, GitHub Actions)
• Creating Ansible playbooks or Helm charts
• Working with data that benefits from human readability and comments
• Dealing with multi-line string content

What Is JSON and When Should You Use It?

JSON (JavaScript Object Notation) is a lightweight, machine-friendly data interchange format:

{
  "name": "Alice",
  "age": 30,
  "active": true,
  "tags": ["developer", "typescript"]
}

JSON is the universal language of APIs and web services.

Use JSON when:

• Exchanging data between frontend and backend APIs
• Storing configuration in package.json, tsconfig.json
• Working with NoSQL databases (MongoDB, Firebase)
• Interfacing with REST or GraphQL APIs

How YAML ↔ JSON Conversion Works

YAML to JSON

The converter parses your YAML document and outputs equivalent JSON:

JSON to YAML

JSON objects become YAML block mappings and arrays become block sequences:

{"name": "Alice", "tags": ["js", "ts"]}

→

name: Alice
tags:
  - js
  - ts

Supported YAML Features

• Block mappings: key: value pairs with indentation-based nesting
• Block sequences: - item lists
• Scalars: strings, integers, floats, booleans, null
• Quoted strings: double (") and single (') quotes with escape sequences
• Multi-line literals: | (literal block — preserves newlines) and > (folded block — joins lines)
• Flow collections: inline {key: val} mappings and [a, b, c] sequences
• Comments: lines starting with # are ignored

Handling Edge Cases

Multi-line Strings

YAML block scalars let you write multi-line strings cleanly:

description: |
  Line 1
  Line 2
  Line 3

Converts to JSON: {"description": "Line 1\nLine 2\nLine 3\n"}

Type Coercion

YAML automatically coerces unquoted values to their natural types. To keep a value as a string, quote it:

port: 8080          # number → 8080
version: "1.0"      # string → "1.0"
enabled: true       # boolean → true

Sort Keys

Enable Sort keys to output keys in alphabetical order — useful for diffs and consistent formatting across team members.

Frequently Asked Questions

Can I convert a large YAML file? Yes. The converter runs entirely in your browser — performance depends on your device. For very large files (tens of megabytes), consider splitting the data first.

Are YAML comments preserved in JSON output? No. JSON does not support comments, so YAML comments are discarded during conversion. When converting JSON back to YAML, no comments are added.

What happens to YAML anchors and aliases? Anchors (&) and aliases (*) are not currently supported. Expand them before converting.

Is my data private? Yes. All processing happens entirely in your browser. No data is sent to any server, stored in any database, or logged anywhere. The tool works offline once the page loads.

What is the difference between | and > in YAML? | (literal block scalar) preserves newlines exactly as written. > (folded block scalar) folds newlines into spaces, treating the text as a single paragraph. Both are useful for embedding multi-line content cleanly in YAML.