Cloudflare Worker integration: identify visitors from your own domain

What you get

Identification works the same as in the standard setup and catches the same things. The difference is where the requests go: to your site, which hands them to us.

• The agent and its calls are served from your own domain instead of a third-party host.
• The real visitor address and location reach our servers, so the filters and rules you set apply to the visitor, not to the Worker.
• You keep control: the Worker runs in your Cloudflare account and we never hold a Cloudflare credential of yours.
• Cookies are never passed in either direction.

Deploy it in a few minutes

You need a Cloudflare account with your site on it, and a free FingerPrint Checker account.

• In the console, open your project settings, Cloudflare proxy, and create a proxy secret. It is shown once, so copy it.
• Deploy the Worker from the open-source repository with the Deploy to Cloudflare button, or with wrangler.
• Store the secret in the Worker as FPC_PROXY_SECRET.
• Add the route yoursite.com/fpc/* to the Worker. To use another path, set FPC_PATH in the Worker (the default is fpc) and use the same path in the route and in the agent.
• Point the agent at your own path, as shown below, and ship.

Worker source and deploy instructions on GitHub →

Rotate the secret without downtime

A project keeps an active and a previous secret, and both are accepted. Create a new one, put it in the Worker, then delete the previous one. Changes reach every server within a minute, so keep the old value in place for at least that long.

Safe by design

Our servers accept the visitor details the Worker passes on only from a caller that proves itself with your project secret, and the Worker discards anything a browser tries to supply in their place. A request with a wrong secret is refused and is not billed, so nobody can pose as one of your visitors.

Works with your filters and rules

Request filtering and rules see the forwarded visitor, so an IP deny list or a rule on country, VPN or Tor applies to the person at your site. Events from this setup are marked as proxied.

Rule templates to start from →

Point the agent at your own path

Replace yoursite.com with your domain. The path must match both the route you gave the Worker and its FPC_PATH setting (default fpc).

import { load } from '@fingerprintchecker/agent';

const fp = await load({
  endpoint: 'https://yoursite.com/fpc',
  scriptUrl: 'https://yoursite.com/fpc/agent.js',
});

Frequently asked questions