FAQ
Questions worth answering up front. Anything else: support@thumblens.app
Is it really free? What's the catch?
Every feature is free, with no limits, no account and no ads. The catch, if you want to call it one: it is made by one person, so support is one person's inbox and updates come when they come. If a paid version is ever added it will be for new features — nothing that is free today will be taken away.
Why does the preview not look exactly like YouTube right now?
Because it is a simulation, not a live page. ThumbLens draws its own generic feed — that is what makes it work offline, need no access to your browsing, and never break when a platform changes its markup. The trade-off is that the layout is an approximation, and platforms restyle themselves a few times a year. We re-check the layouts on a monthly cycle and ship parity updates; if something looks noticeably off, tell us and it will be in the next release.
What data does ThumbLens collect?
None. Your thumbnails, titles and history stay in your browser and are deleted when you
uninstall. There is no account, no analytics and no tracking, and while you use it the
extension makes no network requests at all — the only page it ever opens on our site is the
feedback page shown when you uninstall. It asks for one permission (storage)
and cannot read the pages you visit. Full detail in the
privacy policy.
Is this the same as YouTube's own Test & Compare?
No, and they work well together. YouTube's tool runs a real experiment after you publish and takes days to reach a result. ThumbLens is for the decision you make before uploading — which of your drafts is worth publishing in the first place.
Does it work in Edge, Brave or Firefox?
Chrome and Chromium browsers such as Edge and Brave should work via the Chrome Web Store listing. A dedicated Edge Add-ons listing and a Firefox port are on the roadmap.
Where do my saved previews go?
Into your browser's local storage on that computer — they do not sync between machines and we never see them. The last 50 are kept. You can wipe everything with Delete all local data on the options page (right-click the toolbar icon → Options).
Will you add AI scoring / CTR prediction?
Maybe, carefully. Anything claiming to predict click-through rate deserves scepticism, and it would mean sending your images somewhere. If it ships it will be optional, clearly disclosed, and never on by default.
How can I help?
Leave a review on the Chrome Web Store. For a free tool with no marketing budget that is genuinely the thing that decides whether anyone else finds it. Bug reports and feature requests to support@thumblens.app are just as welcome.