How to fix Vercel rewrite rules for Sanity Studio?

The rewrite rule you've got is actually correct for a basic SPA setup, but there's a key detail: Vercel automatically serves static files before applying rewrites. So the issue likely isn't the rewrite rule itself—it's probably something else in your configuration.

Here's what you need for a standalone Sanity Studio deployment to Vercel:

{
  "rewrites": [
    { "source": "/(.*)", "destination": "/index.html" }
  ]
}

But wait—if this isn't working, here's what's likely wrong:

1. Wrong Output Directory

Make sure your vercel.json specifies where your built Studio files are. Sanity Studio builds to dist/ by default:

{
  "buildCommand": "npm run build",
  "outputDirectory": "dist",
  "rewrites": [
    { "source": "/(.*)", "destination": "/index.html" }
  ]
}

2. Studio at a Subpath (like /studio)

If your Studio lives at a route like /studio instead of the root, you need to:

a) Configure the basePath in your Sanity config:

// sanity.config.js
export default defineConfig({
  basePath: '/studio',
  // ... rest of config
})

b) Update your rewrite to match:

{
  "rewrites": [
    { "source": "/studio/(.*)", "destination": "/studio/index.html" }
  ]
}

3. Deploying Studio with a Next.js App

If you're embedding Studio in a Next.js app, you don't need rewrites at all—Next.js handles client-side routing automatically. The rewrite rule is only for standalone Studio deployments as SPAs.

4. Build Not Producing index.html

Check your Vercel build logs to confirm that dist/index.html actually exists after the build runs. Run sanity build locally and verify the output.

Common Gotcha: Vercel's Order of Operations

Vercel checks for static files first, then applies rewrites. So your rewrite won't break CSS/JS files—those will be served directly. The rewrite only kicks in for paths that don't match actual files, which is exactly what you want for client-side routing in a single-page application.

If you're still stuck, double-check that your CORS origins are configured correctly in sanity.io/manage for both your Vercel deployment URL and localhost (for development). Also verify that your Vercel integration is set up properly if you're using visual editing features.