JSON vs YAML: Complete Format Comparison

JSON vs YAML Overview

Both are data serialization formats with different strengths.

Quick Comparison

| Feature | JSON | YAML |

|---------|------|------|

| Syntax | Lightweight | More concise |

| Readability | Good | Excellent |

| Comments | No | Yes |

| Parsing | Faster | Slower |

| File Size | Larger | Smaller |

Syntax Comparison

JSON

{
  "name": "John",
  "age": 30,
  "active": true,
  "tags": ["user", "admin"]
}

YAML

name: John
age: 30
active: true
tags:
  - user
  - admin

When to Use JSON

Web APIs - Standard for REST

JavaScript apps - Native support

Fast parsing needed

Machine-generated data

Strict validation required

When to Use YAML

Configuration files - More readable

DevOps - Docker, Kubernetes

Comments needed

Human-maintained files

CI/CD pipelines

Conversion

YAML to JSON (Python)

import json
import yaml

with open('config.yaml') as f:
    data = yaml.safe_load(f)

with open('config.json', 'w') as f:
    json.dump(data, f, indent=2)

JSON to YAML (Python)

import json
import yaml

with open('config.json') as f:
    data = json.load(f)

with open('config.yaml', 'w') as f:
    yaml.dump(data, f)

Common Pitfalls

YAML Whitespace

# Wrong - inconsistent indent
server:
  port: 8080
   host: localhost  # Error!

# Correct
server:
  port: 8080
  host: localhost

YAML Type Coercion

version: 1.0      # Float
country: NO       # Boolean false!

# Force string
version: "1.0"
country: "NO"

Tool Support

| Tool | JSON | YAML |

|------|------|------|

| Browsers | Native | Library |

| jq | Yes | No (use yq) |

| VS Code | Excellent | Excellent |

Advanced Features

YAML Anchors

defaults: &defaults
  timeout: 30
  retries: 3

production:
  <<: defaults

  url: https://api.example.com

development:
  <<: defaults
  url: http://localhost:3000

Multiline Strings

description: |
  This is a multiline
  string in YAML
  that preserves newlines

single_line: >
  This is also multiline
  but becomes single line

Decision Guide

Choose JSON for:

• APIs and data interchange
• JavaScript applications
• Performance-critical apps

Choose YAML for:

• Configuration files
• Human readability
• DevOps workflows

Conclusion

Both have their place. Many projects use JSON for runtime data and YAML for configuration!