Open source: anyone can use, study and modify it, including businesses. Free: no cost, but the code is closed. Freemium: a lasting free plan with paid tiers for extra features. Source available: code is public but the license adds conditions.
FAQ
What is the best free alternative to Zoom?
The most popular picks are Jitsi Meet, Google Meet, Microsoft Teams (free) and BigBlueButton. For meetings with no time limit and nothing to install, use Jitsi Meet. For online teaching, use BigBlueButton.
What can I use for free video meetings longer than 40 minutes?
Jitsi Meet has no time limit. Google Meet allows one-on-one calls of up to 24 hours, while calls with 3 or more people are capped at 60 minutes.