Send with Vercel Functions - Rewrite

This guide shows how to send SMS using Rewrite inside a Vercel Function.

1. Install the SDK

npm install @rewritetoday/sdk

2. Configure environment variables

Add your API key in Vercel Project Settings:

REWRITE_API_KEY=rw...

3. Create the function

app/api/send-sms/route.ts

import { Rewrite } from '@rewritetoday/sdk';

const rewrite = new Rewrite(process.env.REWRITE_API_KEY);

export async function POST() {
  const { data, error } = await rewrite.messages.send({
    to: '+15551234567',
    content: 'hello world',
    tags: [
    	{
     		name: 'source',
     		value: 'vercel-function'
     	}
    ],
  });

  if (error) {
    return Response.json(
      {
        ok: false,
        error: {
          code: 'SMS_SEND_FAILED',
          message: 'Failed to send SMS.',
          detailed: error,
        }
      },
      { status: 422 }
    );
  }

  return Response.json({ ok: true, data }, { status: 200 });
}

4. Test locally

curl -X POST "http://localhost:3000/api/send-sms" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "+15551234567",
    "message": "Hello from Vercel + Rewrite"
  }'

5. Deploy

vercel --prod

For high-volume flows, enqueue requests and send asynchronously to avoid function timeout limits.