Kolkata has a good mix of developer, cloud and security groups. GDG Kolkata organises tech talks, hackathons and seminars around Google technologies and open source. The AWS User Group Kolkata holds meetups and hands-on sessions, including re:Invent recap events. Security learners have it especially well here, since null Kolkata and OWASP Kolkata often run combined monthly meetups that are free to attend.
If you are studying ethical hacking or cloud online, these meetups let you see live demos, ask questions and compare notes with people already doing the job. Offering a short talk on something you learned is a good way to practise and get feedback. Regular attendance is also the easiest route to finding a mentor in the city.
Independent community groups, listed for reference. They are not run by or affiliated with WebAsha.