cors-gen

What This Skill Does

The cors-gen skill is an intelligent utility designed to eliminate the frustration associated with Cross-Origin Resource Sharing (CORS) errors. By acting as an interface between your human-readable requirements and server-side implementation, it generates production-ready CORS configuration tailored specifically to your technology stack. Whether you are working with Express.js, Fastify, Next.js, or other backend frameworks, this tool analyzes your frontend origin and backend environment to construct the appropriate headers, method allowances, and credential policies. It handles complex logic like preflight requests (OPTIONS) and sensitive header management, ensuring that your API is secure yet accessible to your permitted frontend applications.

Installation

To integrate this skill into your OpenClaw environment, execute the following command in your terminal:

clawhub install openclaw/skills/skills/lxgicstudios/cors-gen

Ensure you have Node.js 18+ installed on your system. This skill leverages the OpenAI API to analyze your infrastructure, so please ensure your environment variable OPENAI_API_KEY is correctly set before execution. No local dependencies or heavy installations are required as it utilizes npx for invocation.

Use Cases

• Troubleshooting "CORS blocked" errors in your browser console during development.
• Configuring secure authentication flows when your frontend and backend are hosted on different domains.
• Setting up cross-domain communication for microservices architectures.
• Securing production APIs by moving away from wildcard (*) origins to specific, authorized domain lists.
• Migrating existing applications to new hosting providers like Vercel, Railway, or Heroku.

Example Prompts

1. "I am running a React frontend on localhost:3000 and my Node.js Express API is on localhost:8080. Generate the CORS config to allow credentials and specific headers like Authorization."
2. "Create a production-ready CORS policy for a Fastify API. The allowed origins are 'https://app.example.com' and 'https://admin.example.com'. Only allow GET and POST requests."
3. "My frontend is deployed on Vercel and my backend is on Heroku. I need a secure CORS configuration that handles cookie-based authentication while restricting access to these specific origins."

Tips & Limitations

• Be Specific: Always define your exact production origins. Avoid using the wildcard * if you are using credentials, as browsers will block these requests for security reasons.
• Limit Methods: Do not allow every HTTP method. Explicitly define only what your API requires (e.g., GET, POST, OPTIONS) to minimize the attack surface.
• Test Environment: Always verify your configuration in an incognito window to ensure your browser's local cache is not providing false positives during testing.
• Dependency: This skill is an AI-assisted generator; always review the generated code before deploying it to your production server to ensure it matches your specific architectural constraints.