Yes, on iPhone there are a few. one sec puts an "intervention" in front of the apps you choose. Its App Store listing names Math and typing interventions among others, plus a LENGO integration to "learn vocabulary to unlock social media". Toll: Study to Unlock Apps, which we make, is built only around this idea. Opening a gated app costs a short round of questions, either arithmetic or flashcards from your own notes, or real minutes in a study app. Toll is in App Store review and can't be downloaded yet. Opal is close but different: its Breaks ask you to write an intention and set a timer, not answer questions. Apple's free Screen Time limits apps by time and schedule. It doesn't quiz you.
Disclosure: we make Toll. Facts about other apps come from their own App Store listings, checked November 8, 2026. Nobody paid to be mentioned.
The options, side by side
| App | What stands between you and the app | Can it use your own study material? | Price (US) |
|---|---|---|---|
| one sec | A pause, with interventions you choose. Its notes name Math, typing, Follow the Dot and Rotate Phone. A LENGO integration makes you practise vocabulary. | Not described on its listing. LENGO covers vocabulary. | Free for one app. Pro is $6.99/month, $19.99/year or $99.99 lifetime. |
| Toll: Study to Unlock Apps (ours) | A round of questions, multiple choice or typed, or 15+ minutes in a study app you pick. Then the app opens for 15, 30 or 60 minutes. | Yes. Write cards by hand, or turn notes into a deck with any chatbot and import it. | Free for 2 apps with arithmetic. Pro is $2.99/week, $3.99/month, $29.99/year (free first week) or $49.99 once. |
| Opal | Blocks on a schedule or after a limit. "Breaks": write your intention and set a timer. | No; it doesn't quiz you. | Free download. Plans on its listing run from $4.99 to $99.99. |
| Apple Screen Time | Time Allowances and Schedules. You can lock the settings with a passcode. | No. | Free, built in. |
Prices and features from each app's US App Store listing and Apple Support, checked November 8, 2026. Toll's prices are the ones submitted to the App Store.
How these gates work on iPhone
iPhone apps can't put up a gate in front of Instagram on their own. Most of these apps go through Apple's Screen Time frameworks: Family Controls for permission, Managed Settings to put up the gate, and Device Activity to track time. Toll uses them, and Opal's listing says it uses "Apple's Screen Time API". one sec's listing says it uses Shortcuts automations to show its pause when you open an app.
One practical result: the gate screen Apple shows can't host a quiz. In Toll, the gate tells you what the toll is, and the questions open inside Toll. Answer them, and the app you tapped opens for the window you set. The usage tracking Toll relies on has a 15-minute minimum set by Apple, so Toll's study-time option starts at 15 minutes.
Do the questions actually help you learn?
Maybe a little, if they're from material you need. Testing yourself is one of the best-supported ways to study. A large review rated practice testing and spaced practice the two most useful techniques out of ten, ahead of rereading and highlighting (Association for Psychological Science; Dunlosky et al., 2013). A handful of questions before opening TikTok is a small dose of that. That's why Toll lets you use your own decks instead of trivia. But nobody has studied whether gate questions improve grades, so treat them as a bonus, not a study plan.
The better-supported effect is the friction itself. In a 2023 study of one sec, 280 people who used it for six weeks opened the apps they'd chosen 57% less, and the option to back out mattered most (Grüning et al., PNAS 2023; one co-author created one sec).
How to choose
- You want a quick moment of thought, not homework: one sec. Its pause is the best-studied, and the free tier covers one app.
- You're learning a language: one sec's LENGO integration, or Toll's study-time toll with your language app (for example 15 minutes in Duolingo unlocks Instagram).
- You have an exam and your own notes: Toll. Your deck becomes the toll. Multiple choice, your own decks and the study-time toll are in Pro. The free tier gates 2 apps with arithmetic.
- You don't want to answer anything, just stop: Opal or the free Screen Time limits will suit you better than any quiz app.
Honest limit for all of these: you can delete the app, and the gate is gone. Toll is a nudge for people who want one. It is not a parental control.
Sources
- one sec on the App Store: apps.apple.com/us/app/id1532875441 (description, version notes and in-app purchases; checked November 8, 2026).
- Opal on the App Store: apps.apple.com/us/app/id1497465230 (checked November 8, 2026).
- Apple Support: Screen Time Schedules and Time Allowances (iOS 27). Apple Developer: Family Controls, Managed Settings, Device Activity.
- Grüning, Riedel & Lorenz-Spreen (2023), PNAS 120(8): full text.
- Dunlosky et al. (2013), Psychological Science in the Public Interest 14(1): doi:10.1177/1529100612453266.
- Toll's features and prices: the Toll page.