Last updated 22 September 2026
Stellato Labs is a racket fitting and string-tracking tool. This page explains what it collects and what it does with it. There is no ad tracking, no advertising profile, and no selling of data — this is the whole policy.
By default, nothing you enter leaves your device. Your bag, your fitting answers, and your settings are stored in your browser's local storage only. We never see this data, and closing your browser doesn't lose it, but a different browser or device won't have it either.
Creating an account lets your bag follow you to another device. If you do, we store on our server:
No payment details are ever collected — we don't sell anything through the app — and nothing is collected about you beyond what is listed above and in the next paragraph.
Separately from your account, and whether or not you have one, we keep a short-lived record of failed sign-in attempts and of how many accounts have been created from a given internet (IP) address. This exists only to stop password guessing and bulk signups. It stops counting within an hour, the records themselves are cleared automatically, and the record of failed sign-ins for your address is deleted along with everything else if you delete your account. They are never linked to your bag or your fitting, and never used to work out anything about you.
Your password is never stored. What we keep is a one-way scrambled version of it, which cannot be turned back into your password by us or by anyone who stole the file. That is also why we can only ever offer you a reset link, and can never tell you what your password was.
If you choose "Continue with Google," we ask Google only for your name, email address, and whether Google considers that email verified. We use this to create or match your account by email — we do not request access to your Gmail, Google Drive, contacts, or any other Google data, and we never post anything on your behalf.
An account uses one cookie to keep you signed in. It is not used for tracking or advertising, and it is cleared when you sign out.
If you sign in with Google, a second short-lived cookie is set while that is happening. Its only job is to confirm that the sign-in finishing on our side is the same one that started in your browser, which is what stops someone forging a sign-in on your behalf. It carries no information about you, and it is cleared the moment sign-in completes. If you start a Google sign-in and abandon it, that cookie expires on its own within ten minutes.
Those are the only two cookies this site sets. Our visitor statistics set none at all — see below.
We use Vercel Web Analytics to count visits and to see how many people who start a fitting reach the end of it. It is cookieless: it sets nothing on your device, assigns you no identifier, and cannot follow you to any other site. What it records is the page, and whether a fitting was started or finished — never your answers, your rackets, your name, or your email.
These counts are aggregate and are not linked to your account. We use them to work out which parts of the app are confusing, and nothing else.
If you have an account, you can ask us to email you when one of your rackets is due for a restring. This is off unless you turn it on, either when you create your account or later in Settings, and you can turn it off again at any time in two ways: untick the same box in Settings, or click the unsubscribe link at the bottom of any reminder we send. Either one takes effect immediately, on every device.
A reminder only ever concerns your own rackets and the schedule you set for them. For a given racket we send at most one message a fortnight, with one exception: if a racket goes from due to overdue, that change is worth telling you about straight away, so it is not held back. If more than one racket needs attention on the same day, they come in one email. Once a racket is restrung it goes quiet again until the next time it is due. We do not use this list for anything else — no announcements, no offers, no newsletter.
If you ask to reset your password, we email you a link to do it. This one is not optional in the same sense, because it is only ever sent in response to a request you made. The link stops working after an hour, and it can only be used once.
Settings has a form for telling us something is broken or should exist. Sending one emails us your message along with three things about your setup, which the form shows you before you send: which version of the app you are running, the identifier your browser sends to every website it visits, and whether you were signed in. Nothing from your bag goes with it — not your rackets, not your sessions, not your fitting.
If you are signed in, we include your email address so we can reply. If you are not, there is an optional box for one; leave it empty and the report still reaches us, we simply have no way to answer it. Reports are kept in our email for as long as they are useful and are not used for anything else.
We are a small operation and we don't run our own servers. Three companies hold data on our behalf, all of them in the United States:
None of them are permitted to use your data for their own purposes, and we do not share it with anyone else — not with advertisers, not with data brokers, not with racket or string manufacturers.
We keep your account for as long as you have one. If you delete it, it goes immediately and completely — see below.
One detail worth naming: so that Settings can offer to restore an earlier version of your bag, we keep your last 20 saved versions of it. Older ones are discarded automatically, and all of them are destroyed when you delete your account.
Stellato Labs is not intended for children under 13, and we do not knowingly create accounts for them or collect anything about them. If you believe a child under 13 has created an account, email us at the address below and we will delete it.
Junior players are welcome to use the app — guest mode needs no account, no name and no email address, and works exactly the same.
Settings → Danger zone lets you delete your account and everything attached to it, or clear the data on just this device, at any time. Deleting your account removes your name, your email address, your bag, your fitting, your saved versions and your reminder settings from our database. It is immediate and it cannot be undone.
This policy will change as the app does. The date at the top always says when it last did. If a change ever means we would use your data in a way this version doesn't describe, we'll tell account holders by email before it takes effect rather than quietly editing this page.
Questions about this policy, or a request to delete something: stellatostrings@gmail.com