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Control which routes invoke your Worker for Single Page Applications

Workers

For those building Single Page Applications (SPAs) on Workers, you can now explicitly define which routes invoke your Worker in Wrangler configuration. The run_worker_first config option has now been expanded to accept an array of route patterns, allowing you to more granularly specify when your Worker runs.

Configuration example:

{
  "name": "my-spa-worker",
  "compatibility_date": "2025-06-18",
  "main": "./src/index.ts",
  "assets": {
    "directory": "./dist/",
    "not_found_handling": "single-page-application",
    "binding": "ASSETS",
    "run_worker_first": ["/api/*", "!/api/docs/*"]
  }
}

This new routing control was done in partnership with our community and customers who provided great feedback on our public proposal ↗. Thank you to everyone who brought forward use-cases and feedback on the design!

Prerequisites

To use advanced routing control with run_worker_first, you'll need: