# +Extensions
Additional extensions developed and supported by Extly Tech.
- XT Adaptive Images (opens new window), the best extension to generate responsive images.
- XT Massive Image Optimizer (opens new window), a command-line to optimize images and streamline the usage of optimization tools to improve the web performance.
- XT-K2 Link Item (opens new window), XT-K2 Link Item allows defining relations between the specific K2 item(s)..
- XT YouTube Optimizer (opens new window), XT Video Optimizer detects all Youtube players in a page and replaces them with the default video image, that can be clicked to play the original video player.