JSON to YAML

What is JSON to YAML Conversion?

JSON to YAML conversion transforms data from JavaScript Object Notation into YAML Ain't Markup Language. Both formats represent the same data structures (objects, arrays, strings, numbers, booleans, null), but they use different syntax. JSON relies on curly braces, square brackets, and commas. YAML uses indentation and line breaks, producing output that reads closer to plain text. Unlike XML, neither format requires a schema.

YAML was designed as a human-friendly data serialization format. It is the default configuration language for Kubernetes manifests, Docker Compose files, Ansible playbooks, GitHub Actions workflows, and many CI/CD systems. When your source data is in JSON and your target system expects YAML, you need a converter that reliably preserves every value, type, and nesting level exactly without data loss.

Converting JSON to YAML online is useful when you receive API responses or exported data in JSON and need to paste it into a YAML config file. The conversion is lossless for all standard JSON types: strings, numbers, booleans, null, arrays, and objects map directly to their YAML equivalents. Values containing colons or special characters are automatically quoted so the output is valid YAML.

Why Convert JSON to YAML?

YAML is the standard for config files; JSON is what APIs return. Converting between them lets you use the right format for each task without rewriting data by hand.

JSON to YAML Use Cases

JSON vs YAML Comparison

JSON and YAML can represent the same data, but their syntax and capabilities differ in ways that matter for specific use cases.

YAML Gotchas After Conversion

YAML has parsing rules that surprise developers coming from JSON. These four issues cause the most bugs when working with converted output.

Code Examples

Converting JSON to YAML programmatically requires a YAML serialization library in most languages. The standard library handles JSON parsing; YAML output needs an additional package.

import YAML from 'js-yaml'

const json = '{"host":"localhost","port":3000,"debug":true}'
const obj = JSON.parse(json)
const yamlStr = YAML.dump(obj, { indent: 2 })
console.log(yamlStr)
// → host: localhost
// → port: 3000
// → debug: true

import json, yaml

json_str = '{"host": "localhost", "port": 3000, "debug": true}'
data = json.loads(json_str)
yaml_str = yaml.dump(data, default_flow_style=False, sort_keys=False)
print(yaml_str)
# → host: localhost
# → port: 3000
# → debug: true

package main

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

func main() {
    jsonStr := `{"host":"localhost","port":3000,"debug":true}`
    var data map[string]interface{}
    json.Unmarshal([]byte(jsonStr), &data)

    yamlBytes, _ := yaml.Marshal(data)
    fmt.Println(string(yamlBytes))
    // → debug: true
    // → host: localhost
    // → port: 3000
}

# Using yq (https://github.com/mikefarah/yq)
echo '{"host":"localhost","port":3000}' | yq -P
# → host: localhost
# → port: 3000

# Using Python one-liner
echo '{"host":"localhost","port":3000}' | python3 -c "import sys,json,yaml; print(yaml.dump(json.load(sys.stdin), default_flow_style=False))"

Frequently Asked Questions