Config Format Converter

Convert and validate configuration files between JSON, YAML, and TOML formats. Use when working with config files that need format conversion, syntax validation, or pretty-printing. Supports package.json, pyproject.toml, .yaml/.yml configs, and any structured data files. Ideal for cross-platform project setup, CI/CD config migration, and developer tooling workflows.

Universal configuration file format converter for JSON, YAML, and TOML.

When to Use

• Converting package.json to pyproject.toml or vice versa
• Migrating CI/CD configs between formats (.yaml ↔ .json)
• Normalizing config files for cross-platform projects
• Validating syntax before committing config changes
• Pretty-printing minified config files

Supported Formats

Format	Extensions	Use Cases
JSON	.json	npm, Node.js, VS Code settings
YAML	.yaml, .yml	Docker Compose, GitHub Actions, Kubernetes
TOML	.toml	Python Poetry, Rust Cargo, Go modules

Quick Start

Convert Between Formats

import json
import yaml
import toml

# JSON to YAML
with open('package.json') as f:
    data = json.load(f)
with open('package.yaml', 'w') as f:
    yaml.dump(data, f, default_flow_style=False, sort_keys=False)

# YAML to JSON
with open('docker-compose.yaml') as f:
    data = yaml.safe_load(f)
with open('docker-compose.json', 'w') as f:
    json.dump(data, f, indent=2)

# TOML to JSON
with open('pyproject.toml') as f:
    data = toml.load(f)
with open('pyproject.json', 'w') as f:
    json.dump(data, f, indent=2)

Validate Config Syntax

import json
import yaml

def validate_json(filepath):
    try:
        with open(filepath) as f:
            json.load(f)
        return True, "Valid JSON"
    except json.JSONDecodeError as e:
        return False, str(e)

def validate_yaml(filepath):
    try:
        with open(filepath) as f:
            yaml.safe_load(f)
        return True, "Valid YAML"
    except yaml.YAMLError as e:
        return False, str(e)

Pretty-Print Configs

import json

# Compact to pretty JSON
with open('config.min.json') as f:
    data = json.load(f)
with open('config.json', 'w') as f:
    json.dump(data, f, indent=2, ensure_ascii=False)

Common Workflows

Migrate npm Project to Python Poetry

import json
import toml

# Read package.json
with open('package.json') as f:
    pkg = json.load(f)

# Create pyproject.toml structure
pyproject = {
    'tool': {
        'poetry': {
            'name': pkg.get('name', ''),
            'version': pkg.get('version', '0.1.0'),
            'description': pkg.get('description', ''),
            'authors': [],
            'dependencies': {}
        }
    }
}

# Write TOML
with open('pyproject.toml', 'w') as f:
    toml.dump(pyproject, f)

Convert Docker Compose YAML to JSON for CI

import yaml
import json

with open('docker-compose.yaml') as f:
    compose = yaml.safe_load(f)

with open('docker-compose.json', 'w') as f:
    json.dump(compose, f, indent=2)

Best Practices

• Preserve comments: YAML/TOML comments are lost in conversion; document important notes separately
• Key ordering: Use sort_keys=False to preserve original key order
• Unicode: Always use ensure_ascii=False for international configs
• Validation: Always validate output after conversion
• Backup: Keep original files before bulk conversion

Error Handling

Common issues and solutions:

Issue	Cause	Fix
ScannerError	Invalid YAML syntax	Check indentation (spaces, not tabs)
TomlDecodeError	Invalid TOML syntax	Verify section headers [section]
JSONDecodeError	Trailing commas in JSON	Remove commas before } or ]
Unicode errors	Encoding mismatch	Open files with encoding='utf-8'

Dependencies

pip install pyyaml toml