Overlay scripts vs. real code
AI conversion tools apply changes to your site in one of two fundamentally different ways. The difference decides what you actually own — and what happens the day you cancel.
How overlay tools work
Most AI conversion-optimization platforms install a JavaScript snippet that rewrites parts of the page in the visitor’s browser on every load. Installation is one script tag and experiments ship instantly — but the changes live in the vendor’s script, not in your site: cancel the subscription and every improvement disappears. Runtime rewriting happens after your page renders (flicker, layout shift, another third-party script), search engines mostly read your original served HTML, and redesigns break overlays silently.
How code-level changes work
The alternative is to change the source itself: a Pull Request on your GitHub repository, or an edit to your Shopify theme files. You own every line permanently — version-controlled, reviewable, revertible, still yours if you cancel. There is no runtime dependency, crawlers see the improved page, and every change is a readable diff you approve before it ships. The honest trade-offs: it requires repo or store access, ships at deploy pace rather than instantly, and cannot run dozens of parallel A/B variants.
When an overlay tool is the better fit
Enterprise sites with heavy traffic and a dedicated CRO team running many parallel experiments are what overlay experimentation platforms are built for. Velyr is built for the opposite case: indie founders, small SaaS teams, and store owners who want one well-evidenced improvement a week that they own forever.
How Velyr ships code
Every week, Velyr reads your PostHog analytics, scans your pages, and writes the single highest-impact conversion fix as a GitHub Pull Request or a staged Shopify theme change. You approve or skip with one tap in Telegram or from the dashboard — nothing ships without your YES. After a fix ships, Velyr compares bounce rate in the 48 hours after against the 48 hours before and proposes a rollback if the numbers got worse. €29/month after a 14-day free trial; every fix is code you keep.