The short version
Opal is screen-time control designed phone-first, with polish to match. NGUMU: Screen Time Control is a browser extension that combines work-break timers, intelligent website blocking, enforced full-screen breaks and local productivity analytics in a single popup.
They overlap less than the category labels suggest. Opal is a phone-first screen time app; NGUMU is an enforcement layer for the browser where most knowledge work — and most procrastination — actually happens.
NGUMU vs Opal at a glance
| NGUMU: Screen Time Control | Opal | |
|---|---|---|
| Category | Browser focus & screen-time extension | Phone-first screen time app |
| Platforms | Chrome, Microsoft Edge, Brave | iOS primarily, macOS |
| Work-break cycles | Pomodoro, 52-17, 90-20, 20-20-20, custom | Focus sessions and schedules |
| Website blocking | Blacklist, whitelist, curated presets, active only during focus | App and site blocking on device |
| Break enforcement | Full-screen overlay + pre-break blink warning | Session-based, limited break structure |
| Tab management | Limits distracting tabs during a session | Not a focus |
| Analytics | Focus minutes, sessions, daily/weekly goals, streaks | Screen time trends and focus score |
| Data handling | Local storage, no personal data collected, no account | Account required |
| Price | Free to install, optional Pro | Subscription |
Where Opal is genuinely good
- Excellent iPhone experience and genuinely useful screen-time insight
- Scheduled sessions that build a daily routine
- Attractive reporting that makes trends obvious
We're not interested in strawmen. If the list above describes your bottleneck, Opal is a good purchase and you should make it.
Where Opal leaves a gap
- Weak or absent coverage on Windows and Chromebook browsers
- Subscription pricing for what many people need only in the browser
- No Pomodoro/52-17/90-20 work-break cycles or break overlays
The pattern behind all of these: a tool that lives outside the browser can advise, measure or motivate, but it cannot close the tab. The moment attention wobbles, the distracting site is one keystroke away.
Where NGUMU is stronger
1. Blocking that only runs when you're working
NGUMU enforces blocklists while a focus session is active and steps out of the way the rest of the day. Curated presets cover social media, video streaming and news, so setup is seconds rather than an afternoon of regex.
2. A rhythm, not just a restriction
Blocking removes the bad option; it doesn't create the good one. Pomodoro (25/5), 52-17, 90-20, 20-20-20 or a custom cycle give the session a shape and a finish line. See the full feature list for every cycle.
3. Breaks you actually take
A full-screen overlay makes returning early deliberately awkward, and a pre-break "blink warning" prompts you to rest your eyes before the screen changes — the part almost every competitor skips.
4. Honest numbers, kept local
Focus minutes, session counts, goal progress and streaks live in the NGUMU dashboard and stay in your browser's local storage. No account, no upload, no personal data collected. You can export everything to JSON or CSV whenever you like.
5. Free where it counts
Core timers, blocking, break overlays and analytics are free. Pro adds extended analytics and advanced blocking for people who want them — it isn't a paywall around the basics.
Choose Opal if…
- Your phone is the problem and you live in the Apple ecosystem
Choose NGUMU if…
- Your problem is desktop browsing during work hours
- You want a free, no-account tool that works on Chrome, Edge and Brave
Can you use both?
Yes, and plenty of people should. Opal guards the phone, NGUMU guards the working browser.
Switching from Opal to NGUMU in five minutes
- Install NGUMU from the Chrome Web Store, Edge Add-ons or in Brave.
- Open the popup and pick a cycle — start with 25/5 if you're unsure.
- Apply a curated blocklist preset, then add any site that personally derails you.
- Run one session end to end, including the break. Don't skip the break.
- Check the dashboard after three days and adjust the cycle to what the data shows.
Frequently asked questions
Is NGUMU free?
Yes. Installing NGUMU and using its timers, blocking, break overlays and analytics costs nothing. An optional Pro upgrade adds deeper analytics, extended timer options and more granular blocking.
Does NGUMU work on iOS primarily?
NGUMU runs on Google Chrome, Microsoft Edge and Brave. Any Chromium browser that can install from the Chrome Web Store will work.
Does NGUMU collect my data?
No personal data is collected. Session history, streaks and settings are stored locally in your browser, and you can export or delete them at any time.
Is Opal better than NGUMU?
For its own job — screen-time control designed phone-first, with polish to match — Opal is strong. For running disciplined work-break cycles with enforced blocking and rest inside the browser, NGUMU does more, on more browsers, for free.
Can I keep my Opal subscription and still use NGUMU?
Yes. NGUMU doesn't conflict with other timers, trackers or blockers. Many people pair them exactly as described above.