Pomodoro Timer: https://www.marinaratimer.com/
Each Pomodoro is a 25-minute timer followed by a 5-minute break. After the 4th Pomodoro, there is a 15-minute break.
Pros: customizable time, visually appealing
Cons: the timer is very large
Forest Google Chrome Extension: https://chrome.google.com/webstore/detail/forest-stay-focused-be-pr/kjacjjdnoddnpbbcjilcajfhhbdhkpgk?hl=en
Plants a virtual tree that dies if you open up social media websites.
Pros: very easy to use, also available on mobile devices
Cons: easy to bypass the warning of the plant dying
Google Drive: https://www.google.com/drive/
An online cloud for word/excel/PowerPoint/pdf documents.
Pros: all of your files accessible on any computer
Cons: storage is not unlimited