Numinous
Privacy
Last updated 25 August 2026
Numinous is a Chrome extension that lets you rate YouTube videos and shows those ratings on your Letterboxd profile.
There is no signup, no password and no account with us. The only thing that identifies you is the Letterboxd username already signed in on your browser.
What it stores in your browser
- The videos you choose to rate: video id, title, channel name, length, your rating, an optional note, whether you liked or favourited it, and when you rated it.
- Your Letterboxd username, read from letterboxd.com while you are signed in.
- The usernames and avatar URLs of people you follow on Letterboxd, cached for a day so their ratings can be marked on thumbnails.
- An anonymous identifier for this browser, created automatically. It is not tied to an email address or to any account of ours.
What is sent to the server
The server is a Supabase database. There is no other backend.
- Your ratings, so they can appear on your Letterboxd profile. These are stored, and they are public the way a Letterboxd profile is: anyone who knows your username can read them, not only the people who follow you. In practice the people who see them are the ones following you, because that is who Numinous shows them to.
- The ids of videos shown on the page you are viewing, together with the usernames of the people you follow, sent as one lookup so the server can return those people's ratings for those videos. This is what puts friends' marks on thumbnails.
Neither your follow list nor your browsing is stored in the database, but that lookup does have to leave your browser for the feature to work at all, and it happens on YouTube's home, search and watch pages. If that is not a trade you want, friend marks are the only feature that makes it — rating works without it.
What it does not do
- It does not read your YouTube watch history. Only videos you rate are stored.
- It does not collect your email, your password, or any Letterboxd credentials.
- It does not track browsing on sites other than youtube.com and letterboxd.com.
- It does not sell or share your data with third parties, and it carries no advertising or analytics.
Account linking
To prove a Letterboxd account is yours, the extension creates a public list on your profile containing one film and a short code, the server reads your public lists page and checks for that code, and the extension deletes the list. This takes a few seconds and leaves nothing behind. It is the one moment the server fetches a page from letterboxd.com on your behalf.
Deleting your data
Removing the extension deletes everything stored in your browser.
To delete your ratings from the server, email me@numinous.one with your Letterboxd username. There is no automated deletion yet; it is done by hand and you will get a reply confirming it.