Is This Website Built With Bolt? How to Tell
StackBlitz's prompt-driven app builder that runs the whole dev environment in the browser.
Paste the URL into the analyzer and the Overview card shows a “Built with Bolt” badge when the page matches, alongside the full tech stack, SEO audit and performance scores.
What Bolt is
Bolt.new, made by StackBlitz, builds full-stack JavaScript apps from a prompt and runs them inside a browser-based Node environment called WebContainers. Previews live on webcontainer.io addresses, and finished projects are typically deployed to Netlify with one click.
Signals the analyzer checks for Bolt
The detector searches the page HTML for any of these strings. One match reports the builder with high confidence.
bolt.newstackblitz.iowebcontainer.io
How to check it yourself
- Open the page, press Ctrl+U (Cmd+Option+U on a Mac) to view the source, then use Ctrl+F to search it. Search for "bolt.new", "stackblitz" or "webcontainer". Links back to the Bolt project or leftover preview URLs are the giveaway.
- Check the hosting. Bolt's default deploy target is Netlify, so a *.netlify.app address combined with a Vite-built React or Next.js bundle is consistent with Bolt.
- Look for a 'Built with Bolt' badge or footer link, which the builder adds to some templates.
- In DevTools, inspect the bundle names. Vite's hashed /assets/index-*.js files with React are the default Bolt output.
What Bolt sites usually show in an audit
- Output quality depends heavily on the prompt. Audits usually show a reasonable structure but generic metadata, because few prompts mention titles, descriptions or Open Graph tags.
- Most Bolt projects are single-page apps rendered in the browser, so content is invisible to crawlers that skip JavaScript unless a framework with server rendering was chosen.
- Dependencies accumulate as the chat goes on. Unused JavaScript and large bundles are the common performance findings.
- Hosting on Netlify gives HTTPS, a CDN and caching headers by default, which is why security and caching checks often pass.
These are tendencies from audits, not rules. Run the analyzer on the site in question, then use the fix guides for anything it flags, or compare it with a competitor.