How to tell if a website was built with Lovable

To tell if a website was built with Lovable, check the address first, then the page source. Lovable, the AI app builder that was called GPT Engineer until late 2024, publishes projects on its own domains and adds its own scripts and tags. Most Lovable sites carry at least one of them, even on a custom domain.

Below is every Lovable fingerprint we use in Kitsuvo's detector, roughly from strongest to weakest, followed by a quick way to check any page yourself.

Lovable's hosting domains

When someone presses Publish in Lovable without connecting their own domain, the site goes live on one of these:

• *.lovable.app: published projects
• *.lovableproject.com: project previews
• *.gptengineer.app: older projects from the GPT Engineer days
• *.lovable.run and *.lovable.sh: other Lovable-run hosts

An address on any of these answers the question. It is the strongest single signal there is.

Scripts and markup in the source

On a custom domain the address tells you nothing, so look at the code. Open the source (Ctrl+U, or Option+Command+U on a Mac) and search for:

Search for	What it is	Strength
data-lov-id	Attributes from Lovable's component tagger, one per element	Very strong
gptengineer.js or cdn.gpteng.co	The Lovable runtime script	Very strong
lovable-tagger	The build plugin that adds the tagger	Very strong
/lovable-uploads/	Image paths for files uploaded in the Lovable editor	Strong
/~flock.js	A Lovable runtime script on published sites	Strong
Edit with Lovable	The badge Lovable shows on free projects	Strong

Many Lovable sites render with JavaScript, so the raw source can be nearly empty. If your search finds nothing, press F12 and search the Elements panel, which shows the page after its scripts have run.

Default meta tags and share images

New Lovable projects ship with placeholder metadata, and plenty of people never change it:

• A meta description of Lovable Generated Project
• <meta name="author" content="Lovable">
• <meta name="twitter:site" content="@lovable">
• An Open Graph share image served from lovable.dev, often a generic Lovable card
• A tab title of Lovable App, or the Vite default Vite + React + TS

Each of these names Lovable outright, so a single one is good evidence. Paste the link into a messaging app: if the preview shows a Lovable card instead of the site's own image, you have your answer without opening the source at all.

A 30-second check in the console

For a faster test, open the developer tools (F12), go to the Console tab and paste this. It only reads the page and changes nothing:

[...document.querySelectorAll('script[src], img[src]')].map(e => e.src)
  .filter(s => /gpteng|lovable/i.test(s))
  .concat(document.querySelector('[data-lov-id]') ? ['data-lov-id present'] : [])

An empty list [] means none of these fingerprints is on the page. Anything else is a hit, and the output tells you which.

Only paste code you understand into a console, and never on a page that asks you to. That request is a common scam trick.

Style signs that point to Lovable

Lovable generates React with Tailwind CSS and the shadcn/ui components, so its sites share a look: rounded cards, soft shadows, a gradient hero, and class names like text-muted-foreground in the source. Toast notifications from the Sonner library are common too.

These are weak signs. Bolt, v0 and many human developers use exactly the same stack. They support a fingerprint; they do not replace one. Our builder fingerprint guide shows how to tell Lovable apart from the others.

When a Lovable site shows no fingerprints

Lovable lets people sync their project to GitHub and host it anywhere. Some fingerprints, like the component tagger, only appear in preview builds. Others disappear when someone tidies up the metadata. A determined owner can remove them all.

In that case, the honest result is "possibly vibe coded" or "no strong AI signs", depending on what is left. A detector that claims certainty on a clean site is guessing.

Checking for Lovable automatically

Kitsuvo is our no-AI web browser for Mac and Windows. It runs every check on this page, and the equivalent checks for about 20 other builders, on each page you open. When it finds Lovable it says so in the address bar, with a score and the exact evidence it matched. It runs on your computer and is free.