Foundler - Online hackathon weekends. Attend every other week.
TechEvents.co - Tech and startup events aggregator
HackHub - Host tech events and hackathons with ease 👨💻🛠
Calendify - Calendify is an event community where you can share, publish, and subscribe to event calendars. It helps you to stay informed about what you are interested in and what is yet to come.
Confs.tech - Open source list of tech conferences: JS / Ruby / Data etc.
Event Hunt - Startups and Tech Events Curated By Locals