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Cognitive app & website blocker for iOS and Chrome that stops doomscrolling with adaptive math puzzles. Generous free tier (up to 3 limits for unlimited apps), 100% local privacy, optional one-time Lifetime Pro.

Which is more popular?
Website, pricing, platforms and company facts side by side.
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| Website | nullstack.app | novasynapse.com |
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| Platforms | — | |
| Company | — | Startup from Estonia · 2026 |
| Listed in |
In their own words, as submitted to SaaSHub.


No description of Nullstack yet.
Scroll Brake is a native iOS (Screen Time / FamilyControls API) and Chrome Extension app & website blocker that replaces passive countdown timers with active cognitive friction — requiring you to solve adaptive mental math challenges before distracting feeds open. Key Capabilities Cognitive...
What each product offers, as listed by its team.


Possible disadvantages
Walkthroughs and reviews on video.
Full-stack with Nullstack - Part 3
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How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Nullstack and Scroll Brake.
Scroll Brake's answer:
We noticed that standard app blockers fail in two ways: strict hard blocks force users to delete the blocker during an urgent message, while passive 5-second delays become invisible to muscle memory. Escalating mental math creates the exact cognitive pause needed to close the app voluntarily.
Scroll Brake's answer:
Native Swift, SwiftUI, Apple FamilyControls / ManagedSettings / DeviceActivity frameworks on iOS, and TypeScript / Manifest V3 for the Chrome Extension.
Scroll Brake's answer:
Instead of passive countdown timers or breathing animations that muscle memory learns to ignore within days, Scroll Brake uses active cognitive friction — requiring you to solve adaptive mental math puzzles (with escalating daily difficulty) before distracting apps or websites open.
Scroll Brake's answer:
Scroll Brake's answer:
Developers, students, founders, and knowledge workers with ADHD or high screen exposure who want to stop compulsive doomscrolling on iPhone and Chrome without surrendering their privacy or paying $100/year.
Share your experience with using Nullstack and Scroll Brake. For example, how are they different and which one is better?
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