How to Convert JSON to YAML in Python [Complete Guide]

Prerequisites

Before you start, make sure you have:

• Python 3.x installed (check with python --version)
• pip package manager (comes with Python)
• A terminal or command prompt

Install PyYAML

Python doesn't have built-in YAML support (unlike JSON, which is in the standard library). You need to install the PyYAML library. If you prefer using the command line instead, check out our CLI and yq guide.

# Install PyYAML
pip install pyyaml

# Or with pip3 on some systems
pip3 install pyyaml

# Verify installation
python -c "import yaml; print(yaml.__version__)"

PyYAML supports YAML 1.1 and is the most popular YAML library for Python. For YAML 1.2 support, consider ruamel.yaml instead. Need to do this in another language? See our JavaScript, Java, or Go guides.

Convert JSON to YAML in Python

Here's how to convert a JSON file to YAML in Python:

Step 1: Read JSON File

import json
import yaml

# Read JSON file
with open('data.json', 'r') as f:
    data = json.load(f)

Step 2: Convert to YAML

# Convert to YAML string
yaml_output = yaml.dump(data, default_flow_style=False)
print(yaml_output)

Step 3: Save to YAML File

# Save to YAML file
with open('data.yaml', 'w') as f:
    yaml.dump(data, f, default_flow_style=False)

Complete Example

import json
import yaml

def json_to_yaml(json_file, yaml_file):
    """Convert a JSON file to YAML format."""
    # Read JSON
    with open(json_file, 'r', encoding='utf-8') as f:
        data = json.load(f)
    
    # Write YAML
    with open(yaml_file, 'w', encoding='utf-8') as f:
        yaml.dump(data, f, 
                  default_flow_style=False,
                  allow_unicode=True,
                  sort_keys=False)
    
    print(f"Converted {json_file} to {yaml_file}")

# Usage
json_to_yaml('config.json', 'config.yaml')

Convert YAML to JSON in Python

Converting YAML back to JSON is equally simple:

import json
import yaml

def yaml_to_json(yaml_file, json_file):
    """Convert a YAML file to JSON format."""
    # Read YAML (use safe_load for security!)
    with open(yaml_file, 'r', encoding='utf-8') as f:
        data = yaml.safe_load(f)
    
    # Write JSON
    with open(json_file, 'w', encoding='utf-8') as f:
        json.dump(data, f, indent=2, ensure_ascii=False)
    
    print(f"Converted {yaml_file} to {json_file}")

# Usage
yaml_to_json('config.yaml', 'config.json')

Convert JSON String to YAML

For in-memory conversion without files:

import json
import yaml

def json_string_to_yaml(json_string):
    """Convert a JSON string to YAML string."""
    # Parse JSON string
    data = json.loads(json_string)
    
    # Convert to YAML
    yaml_string = yaml.dump(data, default_flow_style=False)
    return yaml_string

# Example usage
json_str = '{"name": "John", "age": 30, "skills": ["Python", "YAML"]}'
yaml_str = json_string_to_yaml(json_str)
print(yaml_str)

Output:

age: 30
name: John
skills:
- Python
- YAML

Handling Complex Data Types

Dates and Datetimes

JSON doesn't have a native date type, but YAML does:

from datetime import datetime
import yaml

data = {
    "created": datetime.now(),
    "expires": datetime(2025, 12, 31)
}

# yaml.dump() handles datetime objects automatically
yaml_output = yaml.dump(data, default_flow_style=False)
print(yaml_output)
# Output:
# created: 2025-12-17 10:30:00.123456
# expires: 2025-12-31 00:00:00

Multi-line Strings

import yaml

data = {
    "description": """This is a long description
that spans multiple lines.
It preserves line breaks."""
}

yaml_output = yaml.dump(data, default_flow_style=False)
print(yaml_output)
# Output uses literal block scalar (|)

Nested Objects

import json
import yaml

complex_data = {
    "server": {
        "host": "localhost",
        "port": 8080,
        "database": {
            "name": "mydb",
            "credentials": {
                "user": "admin",
                "password": "secret"
            }
        }
    }
}

yaml_output = yaml.dump(complex_data, default_flow_style=False)
print(yaml_output)

Common Errors and Solutions

Handle Errors Gracefully

import json
import yaml

def safe_json_to_yaml(json_file, yaml_file):
    """Convert JSON to YAML with error handling."""
    try:
        with open(json_file, 'r', encoding='utf-8') as f:
            data = json.load(f)
        
        with open(yaml_file, 'w', encoding='utf-8') as f:
            yaml.dump(data, f, default_flow_style=False)
        
        return True
    except FileNotFoundError:
        print(f"Error: File '{json_file}' not found")
    except json.JSONDecodeError as e:
        print(f"Error: Invalid JSON - {e}")
    except yaml.YAMLError as e:
        print(f"Error: YAML conversion failed - {e}")
    except Exception as e:
        print(f"Error: {e}")
    
    return False