Privacy Policy

Last updated: October 27, 2026

The short version. The site has two modes, and they are different on this page. In Individual mode — the default, and no account needed — almost everything you type, your PRs and training log included, never leaves your own device, unless you switch on syncing off on My PRs (it is on by default once you are signed in). In Team mode you need an account and the practices you log are stored on a server, where everyone else on your team can read them: that is the point of a team log, and it is explained again on the page where you type them. Either way, what is sent to a server is your email, password and chosen username when you make an account, plus whatever you type into the AI features (coach messages, workout-generator settings and notes, visualizer prompts, 3D-reconstruction cues). Nothing is sold, and there is no advertising or tracking.

1. Who runs this site

Tidelyne is an independent educational project operated by Scarpline. It is run by an individual competitive swimmer, not a company with staff or investors. Contact: danielswims101@gmail.com

2. What is stored on your device only

These use your browser's local storage. They are never transmitted to us, and we cannot see them. Clearing your browser data deletes them permanently, which is why the My PRs page offers an Export Backup button (and an Import to restore it on another device). This list describes Individual mode; for Team mode see section 4.

Signed in, your training data is saved to your account. Your PRs, your training log, your swimmer name and your planner and timer settings are kept on your account so the same data opens on your phone and your laptop. It is on by default once you are signed in; the Your Account panel on My PRs turns it off for a device. Only you can read it. It is tied to your account and nobody else's, your coach included, and team mode never reads it. It is a merge, not a copy: sessions from every device are kept together by their own id, so logging on your phone never overwrites what you logged on a laptop, and no device can delete another device's sessions. Deleting a session is a deliberate act and that deletion does travel. Delete the copy on my account, on the same panel, removes everything from the server and leaves your device untouched; turning the switch off stops this device syncing but does not delete what is already there.

Your swimmer name and personal records
Which mode you chose, Individual or Team, so the site does not ask every time
Your training log entries in Individual mode (the weekly totals and charts on the Analytics page are computed from them each time and are not stored). Practices you log in Team mode are stored on a server instead — section 4
Your Race Planner goals, meet dates, fitted race-predictor profile and last split plan, your PR course, timer settings, analytics chart preferences, recent searches, the last release you read on the What's New page, and small interface preferences such as the search shortcut
If you log in, your sign-in session (a token, not your password) is kept in the browser so you stay logged in; Log out removes it

3. What is sent to a server

What is sent to a server, when and why
Data	When	Why
Email address	Only if you create an account	To log you in and let you reset your password
Password	Only if you create an account	Stored hashed by our authentication provider — never in readable form, and never visible to us
Username you choose	Only if you create an account	To show who is logged in
Your confirmation that you are 13 or older, with the time you gave it and the date of the Terms you agreed to	Once, when you create an account	Kept with the account as the record of the age check the Terms require; it is not used for anything else
Text you send to the AI features (coach messages, workout-generator settings and notes, visualizer prompts, 3D-reconstruction cues)	Each time you use an AI feature	To generate the reply
The time of each AI request (one row per request)	Each AI request	To enforce the 5-messages-per-5-hours limit that keeps the site free
Your AI conversations — the questions you type and the replies, with the chat’s name	When a reply finishes, if you are signed in	So your chats are on every device you sign in to. Only you can read them. They are kept until you delete them: Delete on a chat removes it and its messages permanently
While you are signed in: your PRs, training log, swimmer name and planner and timer settings — the same content the Export Backup file holds	Each time you press Send this device’s copy up, and never otherwise	So the same log opens on another device. Readable only by you; delete it from the same panel
In Team mode only: the practices you log — date, distance, duration, session type, zone, main set, rep distance and rep times, heart-rate range, RPE, and your own notes — plus the board name you pick and any notes you leave on a teammate's practice	Each time you save one, in Team mode	So your log follows you to any device and your team can see it. Readable by everyone on that team — see section 4
In Team mode only: a record of every edit, hide and restore of a practice, keeping the previous values	Whenever a practice is changed	So nobody — including a coach — can quietly rewrite a swimmer's training numbers. Readable only by that swimmer and their coaches
In Team mode only: the time of each attempt to use a team code, with a one-way fingerprint of the code attempted — never the code itself	Each time a team code is entered	To rate-limit guessing, so a squad's code cannot be found by brute force
Your username and email address, in one notification email to the site owner	Once, when you create an account	So we know a real person signed up; it is not used for marketing and is not shared

4. Team mode, and who can see your training

Team mode is off unless you choose it. Choosing it needs an account, and joining a squad needs a code from that squad's coach. Once you are on a team:

Everyone on your team can read every practice you log there — distance, times, heart rate, RPE and the notes you type — and you can read theirs. A team log is a shared log; if you would not want a teammate to read it, put it in Individual mode instead.
You can edit and withdraw your own practices, and nobody else can edit them. Not a teammate, and not your coach. A coach can hide a practice or a note from the team (so there is a way to deal with something inappropriate) and can put it back, but a coach cannot change what you wrote or what you swam. Every change keeps a record of the previous values.
A coach can see who is on the roster and remove someone. Removing a swimmer does not delete their practices — the team's history stays — but it ends their access.
The site owner can read any team's data without appearing on its roster, leaderboard, feed or swimmer count. This exists so the owner can run and support the site and check that a squad of mostly under-18s is not being misused. It is one account, it is written here because a capability like that should not be undisclosed, and it is listed in section 8 among the things you can ask about.
Team codes themselves are never readable by swimmers — only a coach can see their own team's code — and a leaked code can be replaced in seconds.

If you ask us to delete a team account, we anonymise the board name, strip every free-text field you wrote — your notes, main sets, and the notes you left on teammates' practices — and keep the distance and duration history, because other people's charts, the team's totals and the record showing nobody rewrote anyone's numbers are built from it. Say so in your email if you want the whole membership removed instead and we will discuss what that means for the squad's history.

5. Processors we use

Supabase — accounts, authentication, and the AI usage counter.
Anthropic — processes the text you send to the AI features to generate replies.
Resend — delivers two emails when you create an account: a welcome message to you, and a notification to the site owner containing your username and email address. Supabase sends account mail of its own when you ask for one — a password-reset link. Those are the only emails the site sends: there is no mailing list and no marketing.
Vercel — hosts the site files; server logs may include IP addresses.
YouTube (privacy-enhanced mode) — technique videos are embedded through youtube-nocookie.com, so YouTube does not set tracking cookies unless you press play on a video. Video thumbnails are loaded from YouTube's image servers (i.ytimg.com) only when the Videos page (or the stroke-demo strip on the 3D Visualizer page) is open, and the full YouTube player — with its scripts and any cookies — loads only after you press play on a video.
Google Fonts / jsDelivr — deliver fonts, the sign-in library and the 3D engine.

We do not use analytics, advertising networks, or third-party tracking pixels.

6. Please do not send us health information

Do not type medical details, injuries, diagnoses, or anything you would not want stored into any of the AI features. They are general coaching tools, not a confidential medical service.

This matters more than it used to. Signed in, an AI conversation is saved to your account rather than disappearing when you close the page, so anything typed into it is kept until you delete it. Each chat has a Delete button beside it in the list, and deleting a chat deletes its messages with it. If you have already typed something you would rather was not kept, delete that chat and it is gone.

7. Children

Accounts are for users aged 13 and over. We do not knowingly collect personal information from children under 13. If you believe a child under 13 has created an account, email us and we will delete the account and its data promptly. Swimmers under 13 are welcome to use every part of the site that does not require an account — all the technique, calculator, log, and 3D content works without signing in — only the AI features (the coach, the workout generator, the visualizer's AI analysis, and AI 3D reconstruction) and Team mode need an account.

Because a swim squad is mostly under 18, a team code does not by itself let anyone in: unless the coach turns that off, a code puts you in a queue the coach approves, so an adult decides who can read the squad's training. Coaches: please do not ask swimmers to type anything into a team log you would not want their parents to read.

8. Your rights

You can ask us to show you, correct, or delete the data associated with your account at any time by emailing danielswims101@gmail.com. Because on-device data never reaches us, you delete that yourself by clearing your browser data or using the Clear buttons in the app. Depending on where you live, you may have additional rights under laws such as the GDPR or CCPA; we honor those requests regardless of location.

9. Retention

Account records are kept until you ask us to delete them. The AI usage counter stores only the time of each request; rows older than the 5-hour window are no longer used but are kept with the account and deleted with it. A synced copy of your individual PRs and training log is kept until you delete it from My PRs or ask us to, and it is deleted with the account.

In Team mode, a practice you withdraw is hidden from the team rather than erased, so you can put it back; the record of edits and hides is kept with the team, because its whole purpose is to still be there later. Team-code attempt records are kept with the account.

10. Changes

If this policy changes materially, the "Last updated" date at the top of this page will change. Please check back periodically.