Privacy policy
Last updated: November 6, 2026
quant blitz is an interview-prep app for quant trading and quant developer roles. This policy explains what data the app handles, why, and what you can do about it. quant blitz is made by Velori Labs Ltd, a company registered in England and Wales (company number 17529890), which is responsible for this data ("we", "us"). Questions: lukazsdev@gmail.com.
The short version
- No sign-up: the app doesn't ask for your name or email. It works with a random ID.
- Your progress is saved on your device and backed up to our database so it isn't lost.
- Apple or Google handle payments, and RevenueCat manages subscriptions for us. We never see your payment details.
- No ads in the app and no third-party analytics. We advertise quant blitz on Instagram; if you allow it, the app tells Meta when it's installed and opened, to measure those ads. It doesn't track you across other apps or websites, and we don't sell data.
What the app collects and why
Your learning progress
The tracks you study, your placement results, and the lessons, reviews, checkpoints and speed drills you complete; your answers (the option you chose, whether it was right and how long it took); for each speed drill, its setting, length and score; your XP, streaks, hearts and daily goal; your review schedule; and your device's time zone, so streaks follow your local day. This is stored on your device and backed up to our database under a random ID created when you start. We use it to run the app (your stats and review queue) and keep your progress safe, and we may look at answers in aggregate to find questions that are wrong or confusing. On iPhone, the app also keeps the key to that random ID in your iPhone's Keychain, which iOS keeps when an app is deleted, so if you delete quant blitz and install it again, your progress comes back from the backup. The key stays on your iPhone and isn't shared with anyone.
Your subscription
If you buy Premium, as a subscription or a one-time lifetime purchase, the App Store or Google Play takes the payment. RevenueCat, our subscription provider, receives a random app user ID, your purchase and subscription records from the store, and basic device information (such as device model, operating system, app version, country and IP address), so it can tell the app whether Premium is on. We don't receive your name, Apple ID, Google account or payment details.
Measuring our ads
We advertise quant blitz on Instagram and Facebook. On iPhone, the app asks once whether it may help us measure those ads, and you can change your answer anytime in Profile. Only if you allow it, the app starts Meta's software development kit (SDK), which sends Meta Platforms Ireland Ltd ("Meta") app events: that the app was installed and opened, and in-app purchases (the product and price), with basic device information (device model, operating system and app version, language, time zone and IP address), a random ID the SDK creates, and reports of the SDK's own crashes. The app doesn't ask to track you, doesn't give Meta your device's advertising identifier, and turns Meta's advertiser tracking off, so Meta measures installs through Apple's privacy-preserving SKAdNetwork. Your learning progress is never sent to Meta. Meta also handles this data under its own privacy policy.
Technical data
Like any internet service, our database host and RevenueCat (and Meta, if you allow ad measurement) see your IP address when the app connects, and keep it in short-lived server logs for security and troubleshooting.
Reminders
Daily reminders, and the optional reminder before a free trial ends, are scheduled on your device. Nothing about them is sent to us.
Who processes data for us
- Supabase: our database and backups, hosted in London, UK.
- RevenueCat: subscription management, in the United States.
- Meta: measuring our Instagram and Facebook ads (see Measuring our ads), in Ireland and the United States.
- Apple and Google process payments under their own privacy policies.
These providers process data only to provide their service to us. Transfers outside the UK and EU are covered by standard contractual clauses.
Legal basis
If you're in the UK or EU: we process this data to provide the app you asked for (contract), and to keep it secure and working (our legitimate interests). Ad measurement with Meta is based on your consent, which you can withdraw anytime in Profile.
How long we keep it
- On your device: until you use Delete my data or delete the app.
- Backups: until you use Delete my data, or automatically after 12 months without using the app (30 days if you never finished a lesson), so your progress can come back if you reinstall.
- Subscription records: kept by RevenueCat while needed to manage your subscription and to meet legal and accounting requirements.
- App events sent to Meta: kept by Meta under its own retention rules.
Your choices and rights
You can delete your data at any time in the app: Profile → Delete my data removes it from your device and from our backup straight away. Deleting the app removes the data on your device but keeps the backup, so reinstalling on the same iPhone brings your progress back; an unused backup is deleted after 12 months (30 days if you never finished a lesson). To remove everything at once, use Delete my data before deleting the app. You can also ask us for a copy of your data, or to correct or delete it, by emailing lukazsdev@gmail.com. Because the app never asks who you are, we may not always be able to match an emailed request to your data; Delete my data always works. You can cancel a subscription at any time in your App Store or Google Play account settings.
If you're in the UK or EU, you can also complain to your data protection authority (in the UK, the Information Commissioner's Office).
Children
quant blitz isn't directed at children under 16, and we don't knowingly collect their data.
Changes
If the way the app uses data changes, we'll update this page and the date at the top.