--- title: Workers as your fallback origin description: Learn how to use a Worker as the fallback origin for your SaaS zone. image: https://developers.cloudflare.com/dev-products-preview.png --- > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/cloudflare-for-platforms/llms.txt > Use this file to discover all available pages before exploring further. [Skip to content](#%5Ftop) # Workers as your fallback origin If you are building your application on [Cloudflare Workers](https://developers.cloudflare.com/workers/), you can use a Worker as the origin for your SaaS zone (also known as your fallback origin). ## How custom hostname traffic reaches your Worker When customers point their domains to your SaaS zone (for example, `mystore.customer.com` CNAMEs to `service.saasprovider.com`), their traffic enters your Cloudflare zone. Any Worker routes configured on your zone will match this incoming traffic. For example, if you have: * Your SaaS zone: `saasprovider.com` * Your fallback origin: `service.saasprovider.com` * Customer's custom hostname: `mystore.customer.com` (pointed to your zone via CNAME) * Worker route: `*/*` When a visitor requests `mystore.customer.com`, Cloudflare routes that request through your zone. The `*/*` route pattern matches all traffic entering your zone, including traffic from custom hostnames like `mystore.customer.com`. Note You do not need to add individual Worker routes for each custom hostname. The wildcard route pattern (`*/*`) automatically captures all traffic entering your zone, including traffic from customer vanity domains. ## Set up a Worker as your fallback origin 1. In your SaaS zone, [create and set a fallback origin](https://developers.cloudflare.com/cloudflare-for-platforms/cloudflare-for-saas/start/getting-started/#1-create-fallback-origin). Ensure the fallback origin only has an [originless DNS record](https://developers.cloudflare.com/dns/manage-dns-records/how-to/create-dns-records/#originless-setups): * **Example**: `service.example.com AAAA 100::` 2. In that same zone, navigate to **Workers Routes**. 3. Click **Add route**. 4. Configure a route to send traffic to your Worker. Choose one of the following options based on your needs: * **Route all traffic to the Worker** (recommended for most SaaS applications): * **Route**: `*/*` * **Worker**: Select the Worker used for your SaaS application. This pattern routes all traffic entering your zone to the Worker, including requests from custom hostnames (for example, `mystore.customer.com`) and requests to your own subdomains (for example, `app.saasprovider.com`). * **Route all but specific routes to worker**: * **Route**: `*/*` * **Worker**: Select the Worker used for your SaaS application. * Add a second route for your zone's own hostnames with **Worker** set to **None** to exclude them. For example, if your zone is `saasprovider.com` and you want `api.saasprovider.com` to bypass the Worker, create an additional route `api.saasprovider.com/*` with no Worker assigned. More specific routes take precedence over wildcard routes. * **Route only custom hostname traffic to the Worker**: * **Route**: `vanity.customer.com` * **Worker**: Select the Worker used for your SaaS application. 5. Click **Save**. --- Zone name restriction Do not configure a custom hostname which matches the zone name. For example, if your SaaS zone is `example.com`, do not create a custom hostname named `example.com`. ## Interaction with custom origin server Warning When a Worker route matches incoming traffic, the request is handled by the Worker. The [custom\_origin\_server](https://developers.cloudflare.com/cloudflare-for-platforms/cloudflare-for-saas/start/advanced-settings/custom-origin/) setting on individual custom hostnames is bypassed because the Worker processes the request before origin resolution occurs. If you need per-hostname origin routing, implement it within your Worker using `request.headers.get("host")` or `request.cf.hostMetadata` (via [custom metadata](https://developers.cloudflare.com/cloudflare-for-platforms/cloudflare-for-saas/domain-support/custom-metadata/)). ## Related resources * [Hostname routing](https://developers.cloudflare.com/cloudflare-for-platforms/workers-for-platforms/configuration/hostname-routing/) \- Learn about advanced routing patterns, including dispatch Workers and O2O behavior. * [Workers routes](https://developers.cloudflare.com/workers/configuration/routing/routes/) \- Learn more about route pattern matching and validity rules. ```json {"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/cloudflare-for-platforms/cloudflare-for-saas/start/advanced-settings/worker-as-origin/#page","headline":"Workers as your fallback origin ยท Cloudflare for Platforms docs","description":"Learn how to use a Worker as the fallback origin for your SaaS zone.","url":"https://developers.cloudflare.com/cloudflare-for-platforms/cloudflare-for-saas/start/advanced-settings/worker-as-origin/","inLanguage":"en","image":"https://developers.cloudflare.com/dev-products-preview.png","dateModified":"2026-06-19","publisher":{"@type":"Organization","name":"Cloudflare","url":"https://www.cloudflare.com/"},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/cloudflare-for-platforms/","name":"Cloudflare for Platforms"}},{"@type":"ListItem","position":3,"item":{"@id":"/cloudflare-for-platforms/cloudflare-for-saas/","name":"Cloudflare for SaaS"}},{"@type":"ListItem","position":4,"item":{"@id":"/cloudflare-for-platforms/cloudflare-for-saas/start/","name":"Get started"}},{"@type":"ListItem","position":5,"item":{"@id":"/cloudflare-for-platforms/cloudflare-for-saas/start/advanced-settings/","name":"Advanced Settings"}},{"@type":"ListItem","position":6,"item":{"@id":"/cloudflare-for-platforms/cloudflare-for-saas/start/advanced-settings/worker-as-origin/","name":"Workers as your fallback origin"}}]} ```