Nucleus: A Pomodoro Timer and Website Blocker
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This extension has been flagged as potentially malicious.
Extension Delisted
This extension is no longer available in the official store. Delisted on 2025-09-15.
Extension Actions
CRX ID
koebbleaefghpjjmghelhjboilcmfpad
Status
- Malware
- Removed Long Ago
Description from extension meta
Provides a Pomodoro for focused time management and the ability to block websites to help prevent distractions while you work.
Image from store
Description from store
“All of my power is focused on my task; there are no distractions.”
Concentrating your mind and getting into a period of deep focus will make the effort and time that go into your tasks more effective. It will allow you to 'get in the zone', freeing your mind of distractions until your entire body, mind and soul become engrossed into the work.
Nucleus provides a simple, but effective UI to manage these periods of focus and relaxation. Nucleus is based on the Pomodoro technique for time management. When faced with any large task or series of tasks, break the work down into short, timed intervals (called 'Pomodoros') that are spaced out by short breaks. This allows you to immerse your mind, and get good work done.
Nucleus also includes the ability to block distracting websites so you can stay focused on your work.
Find you center.
Latest reviews
- Adjamaja Minsmog
- I've tried a few pomodoro extension, but was never happy with them. But this one is good, and here's why: - built in website blocker - notification sounds don't scare me (not loud, and gentle sounds) - no new pop windows - adjustable focus and break time - can adjust whether to cycle focus and break time or not I honestly think it's great, would heavily recommend!
- Zanrich Du Preez
- So far this works well for me and my use cases. I do self-study on Udemy and can't seem to study all that well these days. LOVE THIS EXTENSION
- One Shot
- I like the app and really want to love in but their are two limitations for me to love this app. One the ring tones don't last that long and are not loud enough which can make you miss the break time. Second reason is this app is just an extension and is not available on desktop as an application. So if you can fix the ringtone/alarm maybe add for how long and how loud the alarm is this will fix the first issue. And the second thing is to either create a website for the people to download this app or to upload this app to Microsoft store and Mac App Store. Thank you in advance
- R Woname
- This was a great extension until it removed the ability to automatically block/unblock websites during work/break periods. Without the link between the timer and the website blocking, there is really no reason to have the two functionalities together in one extension and no real reason to use this over the many other pomodoro timer / website blocking extensions out there. This could be as simple as a checkbox on the website blocking tab that determines whether the blocking/unblocking is automatic.
- Aidan Torrence
- this app is pointless if it doesn't unblock websites during the break. for god's sake.
- Ziggy Shaw
- Seems weird that theres not an option to unblock websites durign the break. Isn't that literally the point of this app? I get that some people were asking for it to always block, but those people could have downloaded one of the thousands of website blocking addons..
- Rafael Atías
- The best pomodoro timer ever!
- Quincey Bailey
- Its perfect! Don't change a thing, except for maybe that bird noise notification
- Aroon Molina Espinoza
- con tiempo o sin tiempo igual bloquea las paginas por lo que solo podras acceder a las paginas cuando desactives el bloqueador de paginas, el tiempo no tiene utilidad porque las paginas las bloqueas y desbloqueas manualmente
- Melinda Colmenero
- I love this app, but the recent update is not unblocking websites during the break period. I would have to manually disable the block in order to view during breaks. Also, if I hit enter for the next line, I have to hit it twice for the blocker to work. I also have to have a space between the first website and the top of the page for the first website to be blocked. Love this app, I use it everyday at work, but this update just has a few bugs.
- Michelle Schink
- Does what it's supposed to do when activated Unfortunately, there are no default settings for blocked pages and when the time has expired or you switch off the timer, the pages are not unlocked again, you have to manually deactivate the block feature in the settings... Very annoying
- Bree Walters
- This is an extremely useful extension. I would change one thing. The ability to change the sound notification. The current sound is not really something I pay attention to. It would be cool to have an option of a pop up window warning us the timer is done as well! I train in my department every week and each employee would be using this if we could change that sound. Thank you!!
- Giancarlo Fattorini
- It works but sadly it also permanently blocks all websites whenever it's not active. So that part of the extension is not useful.
- Nicolás Masciangioli
- La aplicación se ve linda, eso nadie lo discute. Pero el sonido brilla por su ausencia. Si no estás mirando el reloj, ni te enterás que terminó tu pomodoro.
- P Warren
- I would've given it a 5 Star rating b/c I absolutely love the sleek and simple design. Well done! Far better than any other one I've used. i like that you can see the tracker even if it's minimized. I love that it automatically includes the break so you don't have to worry about keeping track. If I had to change ONE thing it would be to added a feature where you can manually add categories, so users can keep track of their productivity for various activities/projects. Nothing to elaborate just a simple log/report. Thank you for the app!
- Leopard
- VERY NİCE THANK YOU MUCH
- Theodora Loufardaki
- Είναι ενδιαφέρων βοηθός και κίνητρο για κάποιες εργασίες και όταν δυσκολεύεται να συγκεντρωθεί κανείς.
- ALINA DRUSILLA RUBIO SUAREZ
- Me encanta, la super recomiendo para mejorar en productividad y concentración al estudiar. Pues no es solo el hecho de "cumplir con su objetivo", quizá sencillo, sino de hacerlo de forma eficaz. La app a pesar de ser simple es muy bonita, y la alarma que te indica los ciclos de tiempo es muy sutil, es decir, su sonido de notificación no es molesto. Además es genial ver el tiempo que va pasando en cuenta regresiva en la extensión fijada. Y no se diga más del método de POMODORO, es excelente para lograr ser un buen estudiante y aprovechar al máximo mi tiempo de estudio, como es mi caso.
- Anonymous Pers0n
- Great but there is several bugs when trying to change the focus time
- faita
- Overall I like this extension. It stops me from going on websites that distract me. The only thing I would change is the messages it gives when you try and access a blocked website instead of something judgemental maybe something motivational like "Do it now, you won't regret it later". I do think the current messages are useful, and somewhat motivational but I think there should be at least some other ones
- Sangjun Park
- Can't access blocked sites after I stopped the timer. I can only access them on 'Break Time'
- Liz Fogo
- I love this extension. It's so exactly what I was looking for. The only thing I'd change would be having a few options for the notification sound. The one on there is incredibly...jarring? Especially if you're listening to music loud. Something just as noticeable, but not as high pitched? Maybe 2 or 3 options?
- vinod varanasi
- good extension. in manual mode without starting the timer it is blocking websites. improvements can be made.
- Lexx Firecore
- Is it possible to add task name for each pomodoro and track their history?
- Gray Wine
- I like the site blocker. That sound is terrifying though, I almost soiled my trousers. Make it something softer or smoother. Like a single piano note, or at least something like a bell.
- Artur Soloviev
- Main flow state machine and / or site list parser are SO poorly implemented I didn't realized how to block a site immediately even after 5 minutes of switching work timer, that senseless "On / Off" switcher on site list and even more senseless "Save" button in the same. You need to propagate the internal state to user or remove all that complicated stuff.
- ganya riya
- This is so useful! Thank you. I think it would be very good if the pomodoro time finishs, the chrome popup dialogs arise. I have to keep Silence in college, so I sometimes didn't notice the pomodoro finish. If there are popup dialogs, notice so fastly and easily. thank you, and sorry for bad english.
- Stel Why
- there is no instructions,I don't know how to turn it off,and it won't let me go to blocked sites even when I don't set it. Great idea. I just don't know how to use it
- Ivan Borisov
- Great but could be even better if this feature could be added I am blocking facebook but I want to whitelist urls containing /ads - www.facebook.com/ads/library Would appreciate if this could be added.
- Flemming Dørken
- My work/break cycles are like this: 25/7, 30/7, 25/7, 30/long break so I would love the individual cycle lengths to be more configurable. That would in practice introduce a long break timer (the fourth break period). The concept of this extension is great though and the execution is simple and effective. Good job.
- Edmo Freitas
- There's a bug where after a while the timer shows the time as something like "-14:0-16" Also the site blocker could block it like the The Great Suspender extension does, where you don't lose the link. Besides that it's a great extension.
- H M
- I think this needs the option to block all sites and then have a whitelist. Some people may just need to block out a couple places, but for me, the internet is too full of distracting places to go to: news, social media, etc. I need to allow sites in.
- Jonathon Gidey
- Works pretty great overall. Two things that would help is automatically unblocking sites when I pause the time and for some reason occasionally I get double the notifications but they are opposites? About once a week I'll get this thing where when it's time to take a break I get the "take a break" notification but also the "time to focus" notification. Then the opposite happens when it's time to focus
- Gabriel Pérez
- Thanks for this extension. Its really helpful. But I would want a way to write what things I am doing in my pomodoro session. Thanks
- Ryan King
- I've been on the "timer" train for years. When I got my first Chromebook some of the Apple apps didn't transfer over - no big deal. This is one of the best extensions I've deployed. Did you know: you can block out sites that want to bug you during your focused time? #topmarks #getthistool #usethistool #makeanotherdollarnotaminute
- sai srikar
- I liked it, i have one enhancement with it, if there is a placeholder where you could know how many pomodoros you have done for the day
- Ahmed Hindy
- Best one on the store 10/10
- greenzanman
- isaac ur cool ++simple, efficient
- josh mcgee
- It only blocks new pages that you go to. So if you want to block twitter, it will only stop you from opening a new twitter tab, it won't shut down your current twitter tab. This makes it virtually useless as a productivity helper
- Syauqi Dir
- i will gift 5 star if remove, read and change data permission.
- Kiran K Telukunta
- Simple to use nice extension. Would be great if you can make non changeable during the operation
- AK
- The website blocker is poorly designed. If I pause/stop the timer, I should be able to then access blocked websites. The extension works well at the office, but it renders your browser unusable at home (when you want to access those blocked sites for more than 5 or 10 minute "breaks").
- Maryant Blanco
- I like it! I would like to put the sites than I allow me to use while I'm studying, to me it's easier
- Matthew Welch
- Doesn't block unless you interact with a blocked website. e.g. I start watching a youtube video during break time. I can continue watching it during focus time until I click on a new video or refresh the page.
- George Gordeyev
- Probably best Pomodoro app in Chrome store. What I would like to see: 1) long break configuration (each 4th rest time is longer then usual) 2) some stats (count of failed pomodoros, overall amount, number of attempts to reach blocked sites etc) 3) stay on top / repositioning of timer window
- Кирилл Мороз
- The app is good, maybe it's the best app at the market in "pomodoro" category, but there are still some things that can be improved. 1. An ability to set up working hours. For example pomodoro cycle starts automatically at 8 am and stops at 5 pm. 2. An ability to set long break time after some number of pomodoro cycles. Long break time must be configurable. 3. Sites in the block list must be blocked immediately when break time is over (now they are blocked only after refreshing the tab). 4. Clock background colour should be changed to red during focus time and to green during break time.
- Fizzah Shaikh
- Really helps me stay off distracting sites without being too intense of a blocker. thanks!
- Sankaran Nepolean
- Exceptional ! When i tempted to access blocked sites, it gives a motivational phrases which is awesome !
- maría losada
- Quite good Is there any way in which I can look up the amount of time or cycles i´ve gone trhough in a day or something similar? I´d also be nice if I could get a notification of when timers end on my phone
- Pau Cervelló Hernando
- This is exactly what I was looking for! I love this extension guys. Good work with it