Privacy

The app keeps your notes on your disk and sends nothing about them anywhere. The optional sync service stores encrypted copies it cannot read. This page lists what each part does with data and who else is involved.

The app

Your notes are plain files on your disk. There is no account to sign into. The app has no analytics and no telemetry. It makes network requests in three situations and you control all of them.

Update check. At launch the app fetches a small file from usedeft.com to see whether a newer version exists. The request carries your app version and your IP address. We keep no log of it. Turn it off in Settings to check by hand instead.

LaTeX packages. If a LaTeX document needs a package the built-in engine lacks, the app asks before downloading it from the Tectonic package archive. Only the package name is sent. With your own TeX installation this never happens.

Sync. Only if you turn on Deft Sync. Without it the app never contacts our servers.

Deft Sync

Deft Sync is opt-in and needs an account. This is what the server holds and what it cannot see.

Account. Your email address, an Argon2id hash of your password, when the account was created and the name of each connected device, which is the kind of computer, such as “Mac”. Sign-in sessions are stored as hashed tokens.

Your files. Each file and file name is encrypted on your device with a key that never reaches us. The server stores the encrypted blobs, the encrypted names and how much storage and history you use. It can see how large each encrypted blob is, which roughly gives away the size of each file. It cannot read your notes, file names or folder structure. Neither can we, our hosting providers or anyone with a copy of the database. Earlier versions of each file are kept in the same encrypted form for up to 30 days, fewer once your version history passes 1 GB.

Device approval. A new device shows a six-digit code that you type into a device you already have. The two devices agree on a secret from that code (SPAKE2) through two messages the server relays but cannot use. The sync key travels sealed under that secret. The server forgets the request after 10 minutes. Details in How the encryption works.

Billing. Payments are handled by Paddle, our reseller and merchant of record. Paddle collects your payment details, billing address and tax information under its own privacy policy. We never see your card number. Paddle sends us your customer and subscription identifiers and the subscription's status so we know whether sync is on.

Requests. The server rate-limits sign-in attempts by IP address in memory only. It keeps no request logs that identify you. Our hosting provider keeps its own short-lived infrastructure logs.

Email. We email you only for password resets and account notices such as a failed payment or a change to our terms. No newsletters. No marketing.

Cookies. sync.usedeft.com sets one session cookie so you stay signed in. usedeft.com sets none. Neither site has advertising trackers.

Who else handles data

Each provider gets only what its job needs. None of them can read your notes.

• A hosting provider in Frankfurt, Germany runs the sync server and its database.
• An object storage provider, also in Frankfurt, holds the encrypted blobs and encrypted database backups.
• Paddle, our reseller and merchant of record, takes payments and handles tax and invoices.
• A transactional email provider in Paris, France delivers our emails.
• A static site host and a content delivery network serve this website, the update manifest and the installers.
• Umami counts visits to this website and stores the counts in Frankfurt.

Email us for the current list by name.

We do not sell data or share it with anyone else unless the law requires it. If we receive a legal request, the encrypted files are useless without your key. We will tell you about the request unless we are forbidden to.

This website

Every page loads a small script from Umami, an open-source analytics service, to count visits. Umami keeps this data in Frankfurt, Germany. It records which page you opened, the site that sent you, and your browser, operating system, device type, screen size, language and country. It sets no cookies, stores nothing in your browser and does not keep your IP address. A content blocker stops it and nothing breaks.

usedeft.com makes two network calls of its own, and only when you click something:

• A download link tells our server which build you chose, such as "mac", and which site or page of ours brought you here, if your browser shares that. The server also notes which country your IP address is in, but not the address itself. This shows us which builds people use and how they found Deft.
• The feedback button sends your message, with an email address only if you give one.

Your rights

You already hold a complete copy of everything you synced: the vault on your disk. To delete your account and all synced data, sign in at usedeft.com/account and choose Delete account (the steps), or email support@usedeft.com from the account's address and we do it within a few days and confirm. You can also ask what we hold about you or have it corrected. In the EU and UK these are your GDPR rights and you can complain to your local data protection authority.

Changes

If this policy changes in a way that matters we email account holders before it takes effect and update the date below.

Last updated 3 October 2026.