What we know about you

Who is responsible

Alexander Ivashkin, an individual, decides what Sparkline stores and why — which in data protection law makes that person the controller. Everything on this page reaches them at hello@ivashkin.dev, including anything you want done with your data.

What is stored

Your account

Your email address, the name you chose to display, which plan you are on and when it ends, and when the account was made and last changed. Your password is never stored — what is stored is an Argon2id hash of it, which cannot be turned back into the password.

Your charts

Each chart's title, unit, colours, series names, size, its read code and its write key — and every reading you send, with the time it arrived. That is data you chose to send us, and what it means is up to you.

Billing

Two identifiers Paddle gave us — one for you as a customer, one for the subscription — plus the renewal or cancellation date. No card number, no billing address, no name on the card. Sparkline is never sent them.

Password resets

A short-lived token, so a reset link can be used once and then not again. It stops working on its own, and the row is deleted with the account.

Not stored

Sparkline keeps no record of your IP address, no browsing history, no device fingerprint and no profile of any kind. The web server in front of it, and the company renting us the machine it runs on, handle your connection the way every web server does and may log its address briefly as part of that.

Why, and on what legal basis

All of it exists to run the thing you signed up for: to let you sign in, to draw your charts, to tell you when a plan is about to end, and to know whether a payment was made. In the language the GDPR uses, that is performance of a contract. Keeping records of what was paid is a legal obligation, and it is Paddle who keeps them.

There is no marketing basis to declare, because there is no marketing. The only email Sparkline sends is about your own account: a password reset you asked for, or a warning that your plan is ending.

Your charts are public

This is the one thing on this page worth reading twice. A chart's read code is a public URL: anyone who has it can open the chart, fetch its picture and read its numbers as JSON, from any site, without an account. That is what makes a chart embeddable, and it cannot be turned off.

So do not put personal data — yours or anyone else's — in a chart title, a series name or a reading. If you already have, delete the chart, which deletes its code along with it.

Cookies

Two, both strictly necessary, neither of which follows you anywhere. One is the signed session cookie that keeps you signed in. The other carries the token that proves a form on this site was submitted from this site. There is no consent banner because there is nothing here to consent to.

Who else ever sees anything

Three companies, each for one job, and none of them is sent anything they do not need. We sell nothing to anybody.

Paddle

Takes the payment as merchant of record. You give them your card details directly, on their checkout; they tell us only that the subscription exists and when it renews. Their own privacy policy covers what they hold.

Mailgun

Delivers the few letters Sparkline sends. They get the address the letter is going to and the letter itself, which is the minimum required to put mail in an inbox.

Google Fonts

The two typefaces this site is set in are fetched by your browser from Google's servers, which means Google sees your IP address when a page loads. Nothing else is sent, and we receive nothing back.

All three are outside the country you are probably reading this in, so your data crosses a border to reach them. Each publishes the safeguards it relies on for that.

How long any of it is kept

Samples are kept as a moving window. Every chart has a capacity, and the oldest reading is dropped as soon as a new one would exceed it — so a chart forgets by design rather than because anybody remembered to delete something. Emptying a chart or deleting it removes its readings immediately.

When Premium ends there are 7 days of grace, and then anything above the free limits is deleted: the charts past the free count, and the samples past the free capacity. Everything else — your account and the charts that fit — is kept for as long as the account exists. Records of what was paid live at Paddle, who keep them as long as tax law requires.

What you can ask for

A copy of what is held, a correction, a deletion, a machine-readable export, or a halt to some particular use of it. Most of it you can do yourself: your name and email are on the account page, each chart's numbers come back as JSON from its own URL, and any chart can be emptied or deleted from its page.

Deleting the whole account is not yet a button. Email hello@ivashkin.dev from the address on the account and it is done by hand, along with every chart and every reading on it, within thirty days. We would rather say that plainly than point at a control that is not there.

If you are in the EU, the UK or anywhere with a data-protection regulator, you can complain to yours. We would appreciate the chance to fix it first.

Keeping it safe

Everything travels over TLS. Passwords are hashed with Argon2id and never stored, logged or emailed. Session cookies are signed, so one cannot be edited into somebody else's. A chart's write key can be rotated from its own page the moment you suspect it has leaked, and the old one stops working immediately.

No service is perfectly safe, this one included. If something happens that puts your data at risk, you will be told by email — not left to read about it.

Changes to this page

The date at the top moves when the text does. A change in what is collected, or in who sees it, is emailed to every account before it happens. The terms and the refund policy sit beside this one.