These four come up together in almost every search for a screen time app, and they’re usually compared feature by feature. That misses the real split. Two of them try to stop you before you open an app. One stops you with a wall on a schedule. One is built around stopping a session that has already gone on too long. Pick the wrong kind and any of them will feel useless within a week.
How do the four compare side by side?
| App | Approach | Best for | Platform | Price | Weak spot |
|---|---|---|---|---|---|
| Opal | Hard blocking on schedules | A strict, polished wall when you will pay for it | iPhone | Free tier; Opal Pro $99 | The price, blocks that sweep up work apps you need, and gamification that can feel performative |
| One Sec | A forced pause before opening | The gentlest possible nudge | iPhone | Free for one app; Pro about $20/year (US) | Easy to autopilot through the breathing prompt, and it doesn’t touch session length |
| ScreenZen | Friction before you open | Opening apps on reflex, before deciding to | iPhone | Free | Easy to blow past the prompt, and the delay doesn’t stop a long session once you’re in |
| AppBlocker | Blocks now, on a schedule, or after a long session | Falling into a session and not coming out | iPhone, Android | Free, ad-supported, no subscription | Handles the reflexive open less well than ScreenZen, has no cross-device desktop blocking, is ad-supported, and isn’t parental controls |
For apps outside these four, including Freedom for cross-device blocking, see Opal alternatives and the full comparison of screen time apps. This page sticks to the head-to-head.
Do they block, or do they delay?
This is the split that matters most. Blocking means the app won’t open during the hours or session you set, so the decision is made ahead of time. Delaying means the app still opens, but only after a pause or a prompt, which breaks autopilot and leaves the choice to you in the moment.
- Block: Opal and AppBlocker.
- Delay: One Sec and ScreenZen.
If a pause is enough to make you put the phone down, a delay app is lighter and less annoying. If you tap straight through any prompt, you need a block.
What does each one do best?
Opal
Opal is the most polished of the four and the one most people try first. It blocks selected apps and sites during schedules or on-demand sessions, with gamified streaks and gems for staying off. If a firm, well-designed wall on a schedule is what breaks your loop, Opal does that job well.
One Sec
One Sec makes you take a breath before a distracting app opens. It’s the lightest touch here, and a good first step if you aren’t sure you need a full tool yet.
ScreenZen
ScreenZen puts a short pause and a prompt, asking what you want to do, between you and the app, plus optional daily open limits. It’s genuinely free, and for the reflexive open it’s the best free tool in this group.
AppBlocker
Disclosure: this is mine. Its Doomscroll Protection lets you pick the apps that are time sinks, and AppBlocker stops you after 15 minutes of use. That’s aimed at the other half of the problem: not the open, but the unbroken session afterwards. It also has Block Now for a set stretch, Scheduled Blocks, a Manual Block that stays on until you deliberately turn it off, and screen-time stats. It needs no sign-up and is free with no subscription.
Where does each one fall short?
Every app here has a real weak spot, mine included, and they’re in the table. In short: Opal costs the most and can feel heavy-handed. One Sec and ScreenZen are easy to tap past once the prompt becomes routine, and neither does anything once you’re already in the app. AppBlocker is weaker than ScreenZen at the reflexive open, doesn’t block on a laptop, shows ads, and isn’t built for managing someone else’s phone.
Which one fits which failure mode?
| If you | Look at |
|---|---|
| Open apps on reflex, before deciding to | ScreenZen |
| Want the gentlest possible nudge | One Sec |
| Want a strict, polished wall and will pay for it | Opal |
| Fall into a session and don’t come out | AppBlocker |
There’s no overall winner, because they aren’t competing for the same job. Diagnose where your time goes first; the app is the easy part.
Questions about these four apps
What is the difference between Opal, One Sec, ScreenZen and AppBlocker?
Opal and AppBlocker block apps, while One Sec and ScreenZen add a pause before an app opens. Opal focuses on scheduled walls, AppBlocker adds a stop after a long session, ScreenZen adds a prompt and optional open limits, and One Sec adds a breathing pause.
Which of these apps is free?
ScreenZen is free and AppBlocker is free with no subscription, supported by ads. Opal has a free tier and a paid Opal Pro, and One Sec is free for one app with a paid Pro tier.
Which one is best for long scrolling sessions?
Of these four, AppBlocker is the one aimed at session length: its Doomscroll Protection stops you after 15 minutes of use in the apps you pick. One Sec and ScreenZen act before you open an app, so they don’t interrupt a session that has already started.
Which one is best for opening apps without thinking?
ScreenZen is the best free tool here for the reflexive open, because it puts a pause and a prompt between you and the app. One Sec does something similar with a breathing pause.
Do these apps work on Android?
AppBlocker is on iPhone and Android. Our comparison lists Opal, One Sec and ScreenZen for iPhone, so check their store pages if you need Android.
If session length is your failure mode
AppBlocker stops you after 15 minutes in your time-sink apps, with schedules and a Manual Block. Free, no sign-up, iPhone and Android.
Get AppBlocker, free Get it on Google Play