Answers first, a person when you need one

A daily habit for software engineers: a five-minute lesson and one question a day, taken from failures and trade-offs in real platforms. Concepts you miss come back for review before you forget them.

In the browser at app.bytewize.dev, and in the iOS and Android apps. Once you are signed in, your progress is the same on every device.

No. You can start as a guest and answer straight away. Sign in with Apple, Google or an email code when you want to keep your progress or use a second device; the guest progress moves into the new account.

At 00:00 UTC, the same moment for everyone, wherever you are. The app shows how long is left in the current day.

Streaks count UTC days, not the days on your clock. Practice late in the evening in the Americas, or after midnight in Asia, can fall into a different UTC day than it seems.

A missed day uses a streak freeze automatically when you have one. A broken streak can be repaired within 48 hours by finishing a double session.

Use Report a problem on the question in the app. Reports go straight to content review, together with the exact version of the question you saw.

Each concept has its own schedule. A concept you get right comes back about a week later, then further apart each time it sticks; one you miss comes back sooner. The review queue in the app holds what is due today.

The daily challenge and every lesson in every track are free, always. Free accounts also get one review session a day, one checkpoint attempt per unit a day, unlimited practice of their mistakes, and one streak freeze a month. In the iOS and Android apps, Free users see ads, and watching a short ad adds a review session (up to two a day) or a checkpoint retake (one a day).

Pro adds unlimited review sessions and checkpoint retakes, the history of past daily challenges, two streak freezes a month with room for five, and no ads.

This happens when the guest on this device had progress and the sign-in belongs to an account that already existed. Accounts are never merged: the app asks which one to keep, and choosing the existing account removes the guest and its progress.

Sign in with the method you used first. If the progress you expect is still missing, write to us with the email of the account.

An account signs in only with the method it was created with. If you started with Google, sign in with Google, even when the email address is the same.

Check the spam and promotions folders, then request a new code. Only the latest code works. Addresses with a typo get no email, so check the address on the screen first.

In the app, open Settings and choose Delete account. Your personal data is deleted, and the deletion cannot be undone.

Deleting the account does not cancel a Pro subscription. Cancel it in the App Store or Google Play first.

$4.99 a month, billed by Apple or Google. There is no free trial at the moment.

Not yet. Pro is bought in the iOS or Android app. It belongs to your account, so once bought it also unlocks the web app when you sign in with the same account.

Make sure you are signed in with the account that bought it; a guest cannot hold Pro. Then open Settings and choose Restore purchases. If Pro still does not show, write to us with the store receipt.

Subscriptions are managed by the store that billed you: in the App Store under your Apple ID and Subscriptions, or in Google Play under Payments and subscriptions. Cancel at least 24 hours before the period ends, or it renews. Deleting the app does not cancel the subscription. Pro stays active until the end of the period you paid for.

Apple and Google handle payments, so refunds are requested from them: at reportaproblem.apple.com for the App Store, or in the Google Play order history. We cannot issue refunds for store purchases ourselves.

Your account details, your answers and your review schedule: what the app needs to show your progress and bring concepts back on time. The privacy policy lists it in full.