Keep Alive

Do Vercel Serverless Functions have cold starts?

Yes. Vercel's serverless platform is built on AWS Lambda, so functions experience the same cold start issues - container provisioning delay after periods of inactivity.

Are Vercel Serverless Functions different from regular Lambda?

Slightly. Vercel optimizes the cold start process, but still can't eliminate it completely. Vercel functions typically have 100-500ms cold starts for Node.js, but can be longer for other runtimes or with many dependencies.

How does Keep Alive keep Vercel functions warm?

Keep Alive sends periodic requests to your Vercel deployment URLs:

• Works with any Vercel serverless function
• No code modifications needed
• Supports preview and production environments
• Handles region-specific deployments

Setup guide

1. Add your Vercel deployment URL to Keep Alive
2. For API routes, include the full path: https://your-project.vercel.app/api/your-function
3. Set ping interval to 5 minutes (standard for Lambda-based platforms)
4. Optionally add custom headers if your API requires them

Best practices for Vercel

• Health checks: Create lightweight health check endpoints
• Static generation: Use Incremental Static Regeneration where possible
• Edge functions: Consider Edge Functions for latency-sensitive operations
• Analytics: Monitor cold start impact with Vercel Analytics

Next.js API Routes vs Edge Functions

Vercel offers multiple function types, each with different cold start characteristics:

• Serverless Functions (API Routes): Standard Lambda-based functions with typical cold starts
• Edge Functions: Run on Cloudflare's edge network with faster (but still present) cold starts
• Edge Middleware: Similar to Edge Functions but run before request matching

Keep Alive works best with Serverless Functions, which benefit most from warming.

Common Vercel function challenges

Vercel functions have some unique considerations:

• Authentication: If using auth, your ping endpoint may need special handling
• Database connections: Prevent connection pool exhaustion during cold starts
• Preview deployments: Each preview gets its own function instances
• Function size limits: Vercel has stricter size limits than raw Lambda

Cost considerations

Keeping Vercel functions warm has minimal cost impact:

• Hobby tier: No additional cost for executions
• Pro/Enterprise: Function executions minimal compared to Vercel's included limits
• Performance benefit dramatically outweighs the small cost increase

Vercel vs other platforms