Svix

Svix Webhooks API Skill

Overview

Svix is the industry standard for sending and verifying webhooks reliably, used by Clerk, Brex, Resend, and thousands of platforms.

Installation

npm install svix
pip install svix

Verifying Inbound Webhooks

To verify a webhook received from Svix or a service that uses standard Svix signatures (like Clerk or Resend):

import { Webhook } from 'svix';

export async function verifyIncomingWebhook(
  rawBody: string,
  headers: Record<string, string>
) {
  const secret = process.env.WEBHOOK_SECRET!;
  const wh = new Webhook(secret);

  const payload = wh.verify(rawBody, {
    'svix-id': headers['svix-id'],
    'svix-timestamp': headers['svix-timestamp'],
    'svix-signature': headers['svix-signature'],
  });

  return payload;
}

Sending Outbound Webhooks via Svix API

import { Svix } from 'svix';

const svix = new Svix(process.env.SVIX_AUTH_TOKEN!);

// Create an application for a tenant
const app = await svix.application.create({
  name: 'Customer Org 42',
  uid: 'org_42',
});

// Send an event message
await svix.message.create('org_42', {
  eventType: 'invoice.created',
  payload: {
    id: 'inv_9981',
    amount: 5000,
    currency: 'USD',
  },
});

AI Pitfalls & Anti-Hallucination Guidelines

• Raw Body Requirement: Passing a JSON-parsed object to wh.verify fails cryptographic verification. Always pass the exact raw body string or buffer.
• Header Casing: Svix headers are lowercase: svix-id, svix-timestamp, svix-signature.

Production Verification Checklist

• Express / Next.js route handler configures raw body reader
• Webhook secret verified against environment (whsec_...)
• Svix timestamp tolerance checked (default 5 minutes)

Last Verified: 2026-07-03