ThumbStash stores your account (email, name) and the thumbnails you collect (video id, title, channel, tags) in Google Firebase.
The browser extension only reads YouTube pages to add the Collect button and to read the title/channel of a thumbnail you choose to save. It does not track your browsing.
AI generations send the reference thumbnail, your prompt and any images you upload to Replicate to generate images. Generated images are stored in your private storage.
Payments are processed by Stripe; we never see your card details. You can delete your account at any time by contacting support.