Todoist | Web, Windows, Mac, iOS, Android | Free and Paid - Its 2-way sync with Google Calendar makes this to-do list a no brainer. Plus it understands natural language such as "every two days starting tomorrow."
Similar apps: Any.do, Remember the Milk, Wunderlist
Habitica | Web, Chrome Extension, iOS, Android | Free - Gamify your to-do list, level up your character, earn gold by completing tasks, buy gear, collect pets and mounts and fight bosses! It's like an RPG, but in real life!
Dynalist | Web, Windows, Mac, Linux, iOS, Android| Free -
Looks like a simple bulleted list, but its organizational features make it the perfect place to put down all your thoughts. If you're currently using Notes, Stickies or similar, you'll probably enjoy Dynalist.
YNAB | Web, iOS, Android | Usually paid, free for current students -
YNAB stands for "You Need a Budget." No need to import transactions, link bank accounts nor start from the very beginning of time. Simply create your accounts and categories and start from day one. Their philosophy is to give every dollar a job. See reports of where your money goes, set goals, and see your net worth.
Notability | iOS and Mac | Paid - This powerful note-taking app that lets you incorporate slides, photos, text, drawings, and audio all in one place. Audio recordings can also be synced up with replays of your own drawings.
RescueTime | Windows, Mac, Linux, Android | Free and Paid - RescueTime automatically tracks how you spend your time on the computer, generates detailed reports on your time use and helps you set goals.
Toggl | Web, Extensions, iOS, Android | Free and Paid - Toggl is a project manager and timer all in one. Make your categories, name your task, hit the timer and track how you're really spending your time.
ColdTurkey and ColdTurkey Writer | Windows, Mac, Android - ColdTurkey is serious business, once you start it, you can't stop it! ColdTurkey itself will block distracting websites and programs, or lock you out of your computer entirely. ColdTurkey writer is a simple text editor that holds you accountable to your goal - whether it's number of words typed or a certain amount of time spent.
Similar app: Self-Control for Mac - Another nuclear option for blocking your distractions
StayFocusd | Chrome Extension | Free - Set allowances for, or block distracting websites to get work done. StayFocusd helps you control your internet usage, has a built-in "nuclear" option, and can even require challenge text to dissuade you from changing the settings.
Newsfeed Eradicator | Chrome Extension | Free - Wipes your newsfeed blank and replaces it with a quote so you can still chat or access important events without distractions.
Also try messenger.com to only access Facebook messages but with none of the distractions.
Digital Wellness (Android) and ScreenTime (iOS) - These are the built-in tools Google and Apple have begun offering in the newest iteration of their operating systems. If you have a newer phone - look out for this tool.
Flipd | iOS, Android | Free and Paid - Flipd helps you unplug and stay focused by encouraging you to engage in "Mindful Moments" with relaxing sounds. For those who are easily distracted, Flipd also offers a complete Full Lock Mode that will prevent you from accessing all but the most essential apps on your phone for the alotted time.
Forest | iOS, Android | Free and Paid - Plant a tree and let it grow on your screen while you work. Beware, if you navigate away from your screen, your tree will die!
AloeBud | iOS | Free and Paid - Cute and gentle reminders to encourage you to take breaks, drink water, and begin building healthy habits
Fabulous | iOS, Android | Free and Paid - Users can follow Fabulous' built-in program to wellness and also set goals for self-care, exercise, meditating and more
Libby | iOS, Android | Free - Did you know most libraries will let you borrow digital books for free? Link up your library card with Libby and check out books from your local library. It's worth the trip to the local library to get your card!
Similar: OverDrive, also utilizes your local library's e-collection
Day One | iOS, Android | Free and Paid - Journaling app complete with picture, weather, tagging and calendar functionality.
Mindfulness Applications: Headspace, Calm, Oak
Headspace and Calm are popular apps for mindfulness meditation - they are available on both iOS and Android and have a free trial with vast libraries. Oak is a completely free app that is only available on iOS.