Cron - Cron Calendar.
OpenCV - OpenCV is the world's biggest computer vision library
zcal - zcal is the fastest way to schedule every meeting for Free and make it personal.
Cloudinary - Cloudinary is a cloud-based service for hosting videos and images designed specifically with the needs of web and mobile developers in mind.
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.
Scikit Image - scikit-image is a collection of algorithms for image processing.