YAML to JSON

What is YAML to JSON Conversion?

YAML to JSON conversion transforms data written in YAML (YAML Ain't Markup Language) into JSON (JavaScript Object Notation). Both formats represent structured data as key-value pairs, sequences, and nested objects, but they differ in syntax. YAML uses indentation and minimal punctuation, while JSON uses braces, brackets, and mandatory quoting. Converting between the two is a common task when moving configuration data between systems that expect different formats.

YAML was designed for human readability. It supports comments, multiline strings, anchors, and aliases, none of which exist in JSON. When you convert YAML to JSON, these YAML-specific features are resolved: anchors are expanded inline, comments are discarded, and multiline blocks become escaped strings. The output is valid JSON that any JSON parser can read.

The YAML 1.2 specification explicitly defines JSON as a subset of YAML, meaning every valid JSON document is also valid YAML. The reverse is not true. YAML documents that use comments, anchors, or complex keys have no direct JSON equivalent and must be simplified during conversion. This tool handles that conversion automatically, producing clean, well-formatted JSON from any valid YAML input.

YAML 1.2 Specification — yaml.org →

Why Use an Online YAML to JSON Converter?

Converting YAML to JSON by hand is error-prone, especially with deeply nested structures or multiline values. A browser-based converter gives you the result instantly and catches YAML syntax errors before they reach your application.

YAML to JSON Use Cases

YAML to JSON Type Mapping Reference

Every YAML data type maps to a specific JSON type during conversion. The table below shows each YAML construct alongside its JSON output. Understanding these mappings helps you predict how your YAML data will look after conversion and avoid surprises with types like booleans or null values.

YAML vs JSON Syntax

YAML and JSON represent the same data model but with different syntax rules. The differences below explain why some YAML features — like comments and anchors — have no JSON equivalent.

Code Examples

Below are working examples for converting YAML to JSON programmatically. Each example parses a YAML string and outputs formatted JSON.

import { load } from 'js-yaml'

const yamlStr = `
server:
  host: localhost
  port: 8080
  ssl: true
`

const json = JSON.stringify(load(yamlStr), null, 2)
console.log(json)
// → {
// →   "server": {
// →     "host": "localhost",
// →     "port": 8080,
// →     "ssl": true
// →   }
// → }

import yaml, json

yaml_str = """
database:
  host: db.example.com
  port: 5432
  credentials:
    user: admin
    password: s3cret
"""

data = yaml.safe_load(yaml_str)
print(json.dumps(data, indent=2))
# → {
# →   "database": {
# →     "host": "db.example.com",
# →     "port": 5432,
# →     "credentials": {
# →       "user": "admin",
# →       "password": "s3cret"
# →     }
# →   }
# → }

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"gopkg.in/yaml.v3"
)

func main() {
	yamlData := []byte(`
services:
  web:
    image: nginx:latest
    ports:
      - "80:80"
`)

	var obj map[string]interface{}
	if err := yaml.Unmarshal(yamlData, &obj); err != nil {
		log.Fatal(err)
	}
	jsonBytes, _ := json.MarshalIndent(obj, "", "  ")
	fmt.Println(string(jsonBytes))
	// → { "services": { "web": { "image": "nginx:latest", "ports": ["80:80"] } } }
}

# Convert a YAML file to JSON with yq
yq -o=json config.yaml > config.json

# Pipe YAML into yq for one-off conversion
echo "name: demo" | yq -o=json
# → { "name": "demo" }

# Python one-liner (no extra install on most systems)
python3 -c "import yaml, json, sys; print(json.dumps(yaml.safe_load(sys.stdin), indent=2))" < config.yaml

Frequently Asked Questions