Short version: we collect almost nothing.

Who we are

MidiSlayer is made by Monoglyph Ltd, a company registered in England & Wales (company number 17364027), registered office 128 City Road, London, EC1V 2NX. We are the data controller for the personal data described here. Questions, or to exercise any of your rights: use the contact form or email hello@monoglyph.co.uk. We are not required to appoint a Data Protection Officer and have not done so; the address above reaches the people who handle this.

This website

No cookies, no trackers, no advertising pixels, and no third-party scripts, with two exceptions you can see coming. The checkout page loads Paddle's payment script and secure payment frame from Paddle, because Paddle takes the payment; that page, and what Paddle sees there, is described under "When you buy" below. And every page loads Cloudflare Web Analytics, a small script that counts page views, referring sites, country and browser type, and page load speed. It sets no cookie, stores nothing on your device, does not fingerprint you and does not follow you to other sites; visitors are estimated from the request itself, not from an identifier. Cloudflare already serves every page (see below), so no new company sees your visit. Fonts are served from our own domain. The download host (download.midislayer.com) keeps a tally of downloads (and the app's update checks, counted the same way) by day, file, country and referring site, with no IP address, no identifier and nothing stored on your device. The site runs on Cloudflare, which processes technical request data such as your IP address to serve and protect the page; we don't read it, combine it with anything, or keep our own copy. The one thing we do ask Cloudflare is which country you are browsing from, so the pricing section can show a price in your currency; nothing is stored. Nothing else is stored in your browser either, except one order reference during checkout, described under "When you buy" below. Because we set no non-essential cookies, there's no cookie banner to click. (The optional account portal on platform.midislayer.com sets one strictly necessary sign-in cookie, described below. Still no banner, because that's the one kind of cookie the law doesn't make you click for.)

If you use the contact form, we receive the name, email address and message you type, and the topic you picked. It goes straight from our own server to our support inbox (delivered by Resend and read in Gmail, both listed below) and is used only to reply to you; our lawful basis is legitimate interest, namely answering the message you chose to send us. Submissions are rate-limited by IP address on our own infrastructure to keep bots out; no third-party form service ever sees them. We keep the conversation as long as it takes to resolve, and support threads follow the retention rules below.

The app itself

MidiSlayer keeps your practice data in a local database on your own device. There are no analytics trackers in the app, by default there is no sign-in and nothing is synced, and nothing watches your playing. We never see what you practise or how you play. Out of the box the app talks to the network for only two things: licence checks with our licensing service (it sends your licence key and a short device label like "Mac · 3f9a", never your practice data) and update checks against our release server. Both fail quietly offline and the app keeps working. If you choose to turn on sync, that adds a third, described in "Optional sync" below; it stays your choice and its switch stays off until you flip it.

Each licence check also leaves one housekeeping note on our server: which of your devices checked in, and when. That note is what draws the device list on your account page, enforces the two-device allowance, and lets us count how many devices were active on a given day as a single anonymous number. It is never a profile of you, it says nothing about what you played, and it is kept with the licence record for the retention period set out below, not a day longer.

Our licensing server also keeps a short rolling request log (time, path, status, IP address) for security and debugging. It overwrites itself after roughly 30 MB and is never joined to your account.

When you buy

Purchases are sold and processed by Paddle.com Market Ltd as our merchant of record and reseller. Paddle is the seller you contract with for the purchase, is a separate data controller for the checkout, and handles all payment and card data under its own privacy policy. We never store your payment details. Paddle's order notification to us carries a payment block (card type, last four digits, expiry, the name on the card); our server drops it, along with any address, before the notification is written down. After you pay, your browser holds the order reference in session storage until you close the tab, so the thanks page can show your key. Nothing else is stored, and it never goes into a URL.

After a sale, Paddle passes us your email address, its customer and transaction references, what you bought and what you paid, which we hold together with your licence key, its status, and your device activation labels. We use this to deliver and support your licence (our lawful basis is performance of your licence with us), and to prevent fraud and handle refunds and chargebacks (our legitimate interest in protecting the business against abuse). This data lives in our own database on a server in France (EU), backed up in encrypted form to Cloudflare R2.

Studio seats are the one purchase that doesn't go through Paddle: we invoice teachers and schools directly. For that we hold the billing details you give us (a contact name and email, your studio or school's name and address, and the invoices themselves) and use them to provide the seats and keep proper accounts. The lawful basis is the contract with your studio, invoices follow the six-year retention rule below, and payment arrives by bank transfer, so no card details are involved at all.

A studio can also give each of its seats a short name, so it can tell which key it handed to which person. That text is free-form, written by the studio, and visible only to the studio on its own account page. We never ask for it and nothing depends on it, so please keep it to something like a lesson slot rather than a pupil's full name. We hold no other information about the people a studio's seats are used by: a pupil needs no account, and we never learn who they are.

Your account (optional)

You never need an account to buy MidiSlayer or to use it. If you want one, there's a small portal at platform.midislayer.com/account where you can see your licence, check which devices it's on, free a device slot and have your key emailed to you again. As the terms say, accounts are for ages 13 and over; the app itself needs no account at any age, and practice data stays on the device either way.

Sign-in works by emailed link, not by password, so there's no password for us to store or for you to lose. When you request a link we keep a scrambled (hashed) copy of it and the IP address that asked for it, purely so we can spot abuse. Links stop working after 15 minutes and those records are cleared within about a day. Signing in sets one cookie on platform.midislayer.com that does nothing except keep you signed in: a random identifier, no tracking. It's strictly necessary for the portal to function, which is why there's still no cookie banner. Sessions end when you sign out, or 30 days after you last used the portal, and stale ones are deleted automatically.

If you ask us to delete your data, your account goes with it: sessions, sign-in links, synced progress and your email address. We keep the licence record and its device labels, pseudonymised, for the six-year accounting period.

Optional sync

If you sign in inside the app and switch sync on, MidiSlayer keeps a small summary of your progress on our server so it can follow you to another machine: your settings, achievements, streaks and best scores, which days you practised over the last few weeks, and, if you use them, the weekly practice goal you wrote and your practice ratings. That's the whole list. It is a summary, not a recording: your note-by-note practice history never leaves your device, sync on or off.

The summary is stored with your licensing data on our server in France (EU), only your signed-in devices can read it, and we keep it until you remove it. You're in control from the app's settings: turn sync off any time (nothing is deleted, it just stops), or choose "Delete cloud data" to erase the summary from our server on the spot. Deleting your account removes it too. Our lawful basis is performance of a contract: you asked for the feature by turning it on.

Who else processes your data

We keep the list of processors short and name them:

We don't sell your data and we don't share it with anyone for their own purposes. Your practice data is not visible to anyone but you: not to a teacher, not to a school, not to us.

Where your data lives

Your licensing data is stored in the EU (France), which the UK recognises as providing adequate protection, and healthchecks.io is an EU (Latvia) provider hosting in the EU. Three of our providers, Cloudflare, Resend and Google, are US-based, so some data may be transferred to the United States. Cloudflare and Resend both certify under the UK Extension to the EU–US Data Privacy Framework, and both data processing agreements incorporate the UK Addendum to the standard contractual clauses as well (verified against their published legal terms, July 2026). The support inbox is a Google account and runs under Google's terms; see their privacy policy. Ask us and we'll point you to the specific safeguard in place.

How long we keep it

Your licence key and activation records: for the life of the licence (pseudonymised for the six-year accounting period if you ask us to delete your account). Sign-in links: minutes, and the record is cleared within about a day. Account sessions: until you sign out, or 30 days after you last used the portal. Synced progress: until you delete it, from the app's settings or with your account. Order and transaction records: we keep these for six years to meet UK tax and accounting law, then delete or anonymise them. Deleted data can remain in encrypted backups for up to 35 days. We don't keep anything longer than we need it.

Your rights

Under UK data protection law you can ask what we hold about you, get a copy, correct it, have it deleted, restrict or object to how we use it, ask for it in a portable form, and, where we rely on your consent, withdraw that consent at any time. Email us and we'll sort it, normally within a month. If we let you down, you can complain to the Information Commissioner's Office at ico.org.uk.

Changes

If this page ever needs to say more, it will say it before the change happens, not after.