- 4clojure
- /r/dailyprogrammer
- AIGaming
- CareerCup
- CodeAbbey
- CodeAcademy
- CodeChef
- CodeCombat
- CodeEval
- CodeFights
- CodeForces - blog entry with more resources
- CodeWars
- CoderByte
- Codility
- CodinGame
- CodingBat
- CyberDojo
- Edabit
- EdufyMe
- Exercism
- HackerEarth
- HackerRank
- Interactive Coding Challenges Repo
- InterviewBit
- Kattis
- LeetCode
- PEG Oneline Judge
- ProgrammingPraxis (Scheme exercises)
- Programmr
- ProjectEuler
- Python Challenge
- Rosalind
- Sphere Online Judge
- StackExchange CodeGolf
- TopCoder
- VirtualJudge
- ChallengeRocket
- DevPost
- Hackathon.io
- Kaggle (Data science competitions)
- Hackster.io - projects and stuff!
- Eventbrite (Search hackathons or game jams)
- NYHackathons
- MonthlyMusicHackathon
- STUPID SHIT NO ONE NEEDS & TERRIBLE IDEAS HACKATHON
- Can usually be found on eventbrite, takes place in a handful of cities
- gist
- Job Puzzles Repo
- /r/learnprogramming FAQ
- "Where can I find programming puzzles.." - SE
- "10 most popular..." - Medium
- "What are good coding challenge websites?" - Quora
- Awesome-educational-games repo
- RosettaCode
- interative-coding-challenges
- awesome-algorithms
- gaerae/awesome-algorithms - catchy name I guess.