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We measured 18 public Bolt sites (median score 49/100) but did not have a sample for v0, so the numbers below cover one side only. The rest of the page compares how each builder can be recognised and what its sites usually get wrong.
| v0 | Bolt | |
|---|---|---|
| Type | AI builder (site written from a prompt) | AI builder (site written from a prompt) |
| Default hosting | v0-*.vercel.app | *.bolt.host |
| Sites in our sample | not measured | 18 |
| Median site score | not measured | 49/100 |
| Sites with a critical problem of their own | not measured | 33.3% |
| Call a Supabase database from the browser | not measured | 33.3% |
| No main heading (H1) | not measured | 77.8% |
| No meta description | not measured | 5.6% |
| Zoom disabled on phones | not measured | 0% |
| Builder badge left on | not measured | 0% |
Highlighted: the better of the two on that row. Lower is better for every percentage.
v0How to spot it: Search the page source for generator. If the content is v0.app or v0.dev, it is v0.
What usually goes wrong: Copied and never finished. v0 output is a starting point. Sites shipped straight from it often keep placeholder copy, "Your Company" links and buttons that go nowhere, which reads as unfinished to a visitor.
BoltHow to spot it: Look at the address: *.bolt.host is Bolt hosting.
What usually goes wrong: Supabase keys in plain sight. We found a Supabase key in the JavaScript bundle of most Bolt sites we scanned. An anonymous key is meant to be public, but only if row-level security is switched on in the database. Many projects never turn it on, and then the key is enough to read every row.
Usually, yes. Each leaves its own traces: v0 on v0-*.vercel.app and in its scripts, Bolt on *.bolt.host and in its own markers. Paste the URL in the scanner above and it names the builder with the evidence it found.
Neither decides it alone. In our sample the biggest SEO gaps were a missing main heading and a missing meta description, both fixable on either platform. Compare the rows above, then scan your own site to see which of them apply to it.
Not by being AI-built. The problems we see most are defaults nobody changed: titles, badges, blocked zoom, and database keys used without access rules. Each is a short fix once you know it is there.
Numbers from The AI-built web, October 2026: public sites on each builder's own hosting, scanned once. Read the method and its limits there.