Last updated: 5 November 2026
Privacy policy
In short
- Without an account, your drawings never leave your browser. They are saved on your computer only.
- With an account, the server keeps your e-mail, your name, your password (scrambled so nobody can read it) and the projects you choose to put online.
- No ads, no tracking cookies, no Google Analytics: only anonymous visit counts, with nothing about you. Your data is never sold.
- You can delete your account yourself at any time (menu of your name → Delete my account), and see or download your data by writing to [email protected].
1. Who runs Circuit Notebook
Circuit Notebook is made and run by one person, Tom Rousseau, a student in electronics and embedded systems in France, as a sole trader (entrepreneur individuel, RCS Chartres 132 318 833). Under the European data protection law (GDPR) I am the data controller: the person responsible for your data.
Contact for anything in this page: [email protected], or the contact form.
2. Using the app without an account
You can use the whole editor without signing up. Your projects, your own symbols and templates, your settings and keyboard shortcuts are saved in your browser (its storage called IndexedDB and localStorage). They are not sent to my server.
The flip side: if you clear your browser data or change computer, they are gone. Keep a copy of important projects (Export → Download .olg file).
Opening a view link (a teacher, a tutor or a classmate shows you a project, read only): no account, no cookie, nothing about you is kept. The server counts how many times the link was opened and how many views are open now (numbers for the person who made it, nothing else). Your browser notes that it already opened this link, so that a reload is not counted twice: that note stays in your browser and is never sent. The project you view is not saved in your browser. Your IP address is only used for a few minutes, in the server's memory, to stop abuse (too many views from one place), and your connection passes through Cloudflare like any visit (section 8).
3. What the server keeps when you have an account
| What | Why |
|---|---|
| Your e-mail address, your name, your username (if you choose one), the colour of your cursor, the date you signed up. | To create your account, sign you in and show who is who in shared projects. |
| Your password, never in clear: only a scrambled version (a hash, made with scrypt) from which the password cannot be read back. | To check your password when you sign in. |
| A sign-in key, kept in your browser. The server keeps only a scrambled copy. It expires after 30 days or when you sign out. | So you stay signed in. |
| The projects you put on the server: drawings, names, thumbnails, comments, version history (with who saved each version), who may open them (members, teams, invite links, view links, rights per sheet). | To keep them for you, sync them between devices and share them. |
| Your friends and teams, and your personal library of symbols if you sync it. | To share projects with them in one click. |
| The invitations you send by e-mail: the address you typed, who sent it, the project and the access it gives. A short notice when someone adds you to a project. | To send the invitation, let only that address join, and show it on your projects page. |
| The view links you make: when, until when, which sheets they show, whether they allow exports, and how many times each was opened. The link itself only as a scrambled copy, like the sign-in keys: the server cannot show it again. | To show the project to the people you send the link to, and nothing more. |
| If you sign in with GitHub (when this button is offered): your GitHub account number, your GitHub name and your verified e-mail address. Nothing else: no access to your code. | To sign you in without a password. |
| If you sign in with Google (when this button is offered): your Google account number, your name and your e-mail address, which Google has verified. Nothing else: no access to your mails, files or contacts. | To sign you in without a password. |
| If you buy Premium or a purchase (from 1.0): your plan, the state and dates of your subscription, what you bought and when, and your customer number at Paddle. Never your card: only Paddle sees it. | To give you what you paid for, and stop it when you ask. |
| If you connect an AI (Account → Connected AIs): the name of the AI app, what you let it do (read, or read and draw), when you connected it and when it was last used; its keys only as scrambled copies; how many drawing steps, symbols and pictures it used each day, kept 30 days. | To let the AI you chose work in your projects with your rights, count its daily limits, and let you disconnect it. |
An AI you connect. It reads the projects your account can open on the server, when it asks for them, and what it reads goes to the company behind that AI app, under its own terms: choose one you trust. I never see your conversation with it. Disconnect it any time in Account → Connected AIs.
Legal basis: providing the service you asked for (GDPR, article 6.1.b).
Where. Your projects and your account are stored in the European Union (Germany), on the servers of Hetzner, behind Cloudflare (section 8).
Who sees what. People you share a project with see your name, username, colour, e-mail address, your cursor and your comments in that project. Your friends and team mates see your name, username and colour. Someone can send you a friend request, or invite you to a project, only if they already know your exact e-mail or username. When someone invites an e-mail address, they are never told whether it has an account here.
As the administrator I see the list of accounts (name, e-mail, date, number and size of projects), to run the beta and its limits. I do not look inside your projects, unless you ask me to help with one.
4. The contact form
When you write to me with the form of the homepage, I receive your name (optional), your e-mail address and your message. They are saved on the server and e-mailed to me, so I can answer you (legal basis: your request, and my legitimate interest in answering it, GDPR article 6.1.f). I delete these messages once the conversation is over, and the server deletes them by itself after one year at the latest.
To stop spam, the server remembers your IP address for one hour (in memory, not in its database) to count the messages sent from it.
5. Anonymous visit statistics
To know whether the site is useful and where its visitors come from, the server counts visits, without cookies and without keeping anything about you. What is stored is only counts per day: how many visitors, which pages of the site were seen (homepage, app, manual…), which site the visitors came from (for example instagram.com or google.com), their country (given by Cloudflare), whether they use a phone or a computer, and a few actions in the app (opening the example, presenting, exporting).
To count each visitor once a day, the server mixes your IP address and your browser's name with a random key of the day into a code that cannot be reversed. This code stays in the server's memory only, and the key is replaced every day: nothing can link your visits from one day to the next, or to you. The IP address itself is never written down. The counts are anonymous and kept as long as the site exists (legal basis: my legitimate interest in knowing how the site is used, GDPR article 6.1.f).
Nothing is counted when your browser asks not to be tracked (Global Privacy Control or Do Not Track).
6. What I do not do
- No advertising, no tracking pixels, no third-party statistics (such as Google Analytics). The links to Circuit Notebook's social media accounts are plain links: nothing is loaded from those sites unless you click them.
- No selling or renting of your data, and no use of your projects for anything other than giving them back to you.
- The fonts and images come from my own server: opening the site does not tell Google, Facebook or anyone else that you came.
7. Cookies and browser storage
Circuit Notebook sets no cookie of its own. It uses your browser's storage only for what
the app needs to work: your sign-in key, the server address, your settings and
shortcuts, your local projects and a copy of the online projects you opened (so they
still work offline; not of a project seen through a view link). Cloudflare, which
protects the site (see below), may set a technical cookie to tell people from robots
(__cf_bm, 30 minutes).
All of these are strictly necessary for the site to work, which is why there is no cookie banner.
8. The services that help run the site
A few companies handle data for me, only for the task below, under contracts that follow the GDPR.
| Service | What for | Where |
|---|---|---|
| Hetzner Online GmbH | The server that runs the site, the database, and its backups. | European Union (Germany) |
| Cloudflare, Inc. | Stands in front of the server: secure connection (HTTPS), protection against attacks, domain name, forwarding of e-mails sent to contact@. It sees the technical data of each visit (IP address, browser, page asked). | Worldwide, incl. the United States* |
| Brevo (Sendinblue SAS) | Sends me the messages of the contact form, and sends you the codes that confirm your e-mail address or let you choose a new password, and the invitations to a project. | European Union (France) |
| Google LLC (Gmail) | The mailbox where I read and answer e-mails sent to contact@. | Worldwide, incl. the United States* |
| Paddle.com Market Limited | Only if you buy Premium or a purchase (from 1.0): Paddle is our reseller (merchant of record). It takes the payment, sends the invoice, handles taxes and refunds, and tells the server what you bought. It receives your e-mail address, your country and your payment details, and keeps its invoices as long as the law asks. For the payment itself, Paddle is responsible under its own privacy policy. | United Kingdom** |
| GitHub, Inc. | Only if you choose "Continue with GitHub". | United States* |
| Google LLC (Google sign-in) | Only if you choose "Continue with Google": Google tells us who you are. Its own cookies are set on google.com, not here. | Worldwide, incl. the United States* |
* Transfers outside the EU rely on the EU–US Data Privacy Framework and on the European Commission's standard contractual clauses. ** The United Kingdom is covered by an adequacy decision of the European Commission.
9. How long data is kept
- Account: as long as it exists. When you delete it, your account, the projects you own (also for the people you shared them with), your friends, teams and library are removed at once. Comments you wrote in other people's projects stay there, as part of their work: ask me if you want them removed.
- Sign-in keys: 30 days at most.
- Plan and purchases: as long as the account exists, deleted with it (a subscription still running is stopped first). Paddle keeps its invoices as long as the law asks.
- E-mailed codes (to confirm the address of a new account, or to choose a new password): 30 minutes at most. They are sent through Brevo.
- Projects on the server: until their owner deletes them. The automatic versions of the history are thinned out as new ones come (20 at most); versions you named stay until the project is deleted.
- Invitations by e-mail: 7 days, then deleted automatically with the address (within a day), or sooner when cancelled or declined. Notices ("Sophie added you to…"): until you open the project or close them, 30 days at most.
- View links: until the person who made them turns them off or deletes the project; 30 days after its end date, a link that ended is deleted automatically.
- Contact messages: one year at most (deleted automatically).
- Backups: to protect your work against accidents, the database is copied every night (the last 7 days are kept on the server, and Hetzner keeps its own copies of the last 7 days on other machines), and before each update of the site (the 5 latest). Something you delete therefore disappears from the backups as these copies are replaced.
10. Your rights
You can at any time:
- see the data I have about you, and get a copy of it;
- correct it (your name, username and colour can be changed in the app);
- delete it: your projects and your whole account, from the app (menu of your name → Delete my account);
- take it with you: projects can be exported from the app as files; I send the rest on request;
- object to a use of your data, or ask me to pause it.
Write to [email protected] from the e-mail address of your account (so I know it is you). I answer within one month.
If you think I do not respect your data, you can complain to the French data protection authority, the CNIL (cnil.fr), or the authority of your country.
11. Security
Every connection is encrypted (HTTPS). Passwords and sign-in keys are stored only in scrambled form. The server is not directly reachable from the internet: it is only reached through Cloudflare. The database is backed up every night. No system is perfect: if a problem ever puts your data at risk, I will tell you and the CNIL, as the law asks.
12. Young users
Circuit Notebook is made for students and engineers. If you are under 15, ask a parent before creating an account. Viewing a project through a view link needs no account and keeps nothing about you (section 2).
13. Changes
If this policy changes, the date at the top changes too. Important changes will be announced on the homepage, or by e-mail to account holders.