--- description: Learn how to use a Worker as the fallback origin for your SaaS zone. title: Workers as your fallback origin image: https://developers.cloudflare.com/cloudflare-for-platforms/cloudflare-for-saas/start/advanced-settings/worker-as-origin/og.png?v=152004ef47a578ea --- [Skip to content](#main-content) > 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. # Workers as your fallback origin Last updated Jun 19, 2026|Copy as Markdown| [View as Markdown](https://developers.cloudflare.com/cloudflare-for-platforms/cloudflare-for-saas/start/advanced-settings/worker-as-origin/index.md)| [Agent setup](https://developers.cloudflare.com/agent-setup/) 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 Caution 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. Was this helpful? YesNo ## On this page [![](https://developers.cloudflare.com/_astro/logo.te5VL_aD.svg)Docs](https://developers.cloudflare.com/) ```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","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/cloudflare-for-platforms/cloudflare-for-saas/start/advanced-settings/worker-as-origin/og.png?v=152004ef47a578ea","dateModified":"2026-06-19","publisher":{"@type":"Organization","name":"Cloudflare","description":"One platform for your apps, agents, and workforce. 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