How to Convert YAML to JSON in Python

Converting YAML to JSON in Python is straightforward with PyYAML. Here's everything you need — from basic conversion to handling edge cases like multiple documents and special YAML types.

Install PyYAML

pip install pyyaml

Basic YAML to JSON conversion

import yaml
import json

# From a YAML string
yaml_string = """
name: Alice
age: 28
active: true
tags:
  - developer
  - python
"""

data = yaml.safe_load(yaml_string)
json_output = json.dumps(data, indent=2)
print(json_output)
# {
#   "name": "Alice",
#   "age": 28,
#   "active": true,
#   "tags": ["developer", "python"]
# }

Convert a YAML file to JSON file

import yaml, json

def yaml_file_to_json(yaml_path, json_path=None):
    with open(yaml_path, 'r', encoding='utf-8') as f:
        data = yaml.safe_load(f)

    json_str = json.dumps(data, indent=2)

    if json_path:
        with open(json_path, 'w', encoding='utf-8') as f:
            f.write(json_str)

    return json_str

# Convert config.yaml to config.json
yaml_file_to_json('config.yaml', 'config.json')

Command line conversion (one-liner)

# Convert yaml file to json
python3 -c "import sys,yaml,json; print(json.dumps(yaml.safe_load(sys.stdin), indent=2))" < input.yaml > output.json

# Or using pipx/scripts
cat config.yaml | python3 -c "
import sys, yaml, json
data = yaml.safe_load(sys.stdin)
print(json.dumps(data, indent=2))
"

Handle multi-document YAML files

import yaml, json

# YAML files with multiple documents (separated by ---)
yaml_multi = """
name: Alice
---
name: Bob
"""

# yaml.safe_load_all returns a generator
documents = list(yaml.safe_load_all(yaml_multi))
json_output = json.dumps(documents, indent=2)
# [{"name": "Alice"}, {"name": "Bob"}]

Handle YAML dates and special types

import yaml, json
from datetime import date, datetime

yaml_str = """
created: 2023-11-14
updated: 2023-11-14T22:13:20Z
"""

data = yaml.safe_load(yaml_str)
# data['created'] is a Python date object — not JSON serializable by default

# Fix: custom JSON encoder for dates
class DateEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, (date, datetime)):
            return obj.isoformat()
        return super().default(obj)

json_output = json.dumps(data, cls=DateEncoder, indent=2)
# {"created": "2023-11-14", "updated": "2023-11-14T22:13:20"}

Convert Kubernetes YAML to JSON

import yaml, json

with open('deployment.yaml', 'r') as f:
    k8s_manifest = yaml.safe_load(f)

# Pretty-print the JSON
print(json.dumps(k8s_manifest, indent=2))

# Or save it
with open('deployment.json', 'w') as f:
    json.dump(k8s_manifest, f, indent=2)