Foundler - Online hackathon weekends. Attend every other week.
MVP-Challenge - 2 weeks. 1 MVP startup. $0 costs
CoFoundersLab - Meet 250,000+ entrepreneurs online
HackHub - Host tech events and hackathons with ease 👨💻🛠
The 24 Hour Startup Challenge - Build startup in 24 hours and win cash prizes 🤑
Confs.tech - Open source list of tech conferences: JS / Ruby / Data etc.