Bolt publishes your project to a free bolt.host address, or to your own domain on a paid plan. Older projects were often deployed to Netlify. Either way, the editor preview working isn't proof the live site works. These are the problems we see most often after a Bolt app goes live.
1. A blank white page after deploy
The HTML loaded but your JavaScript never ran or crashed. Common causes: missing build-time environment variables (e.g. supabaseUrl is required), the wrong publish directory on Netlify, a wrong asset base path, or a runtime crash on first render.
→ Full walkthrough: Bolt.new app blank page after deploy
2. Sign-in sends users to localhost
Bolt's own docs say Bolt projects default to localhost:3000 as the authentication Site URL, which doesn't work for a live app. Bolt usually updates this when you publish, but you may need to set it yourself, especially with a custom domain or several domains. Password-reset links fall back to the Site URL if the return URL isn't on the URI allow list.
→ Fix it: Supabase auth broke after deploy
3. Refreshing a page returns 404 (Netlify)
Client-side routes like /dashboard don't exist as files. On Netlify, add public/_redirects with /* /index.html 200 so every route serves your app.
4. Features that only worked in the editor
An API or backend that only allowed Bolt's preview origin will reject requests from your live domain. Update allowed origins, CORS settings and Supabase redirect URLs to include your production address.
5. Google sees an empty page
Bolt apps are usually React + Vite single-page apps. The server sends a nearly empty HTML file and JavaScript builds the page. Google can render JavaScript, but rendering is a separate step that can fail or be delayed, and many AI crawlers read raw HTML only. → Background: Why is my React SPA not indexed?
What FlowCanary's free check looks at
- Homepage status, speed, redirects and HTTPS
- Key pages found: signup, login, pricing, checkout, contact, privacy, terms
- Broken links on your homepage
- Raw HTML vs a real browser, with a "Google may see a blank page" warning
- robots.txt, sitemap,
noindex, and a missing title, description, canonical or og:image on your homepage - Whether missing pages return a real 404 or a "soft 404" (200)
- JavaScript console errors and failed requests on your homepage and key pages, e.g.
supabaseUrl is requiredor a 404 for your JS bundle - Forms that appear after load, and pages that overflow on phones
FlowCanary looks for hosting and code fingerprints to tell which builder you used. When it spots Bolt, every issue comes with a paste-ready prompt for Bolt. The prompts work when pasted into Bolt either way.