There are already countless chatting software (such as WhatsApp, Skype, Discord, Facebook Messenger), but almost all of them are non-free software based on central servers, and their security and privacy are not guaranteed (any chat history of you will be sold to various companies). Many of them claim to encrypt communication content, even with end-to-end encryption, but when a platform is proprietary, there is simply no way for others to verify that it is as secure and private as it promises to be. Of course, there are some really safe and reliable ones, but they are frequently blocked by governments of various countries and cannot continue (such as Signal, Telegram).

We can see visualizations of neural networks in papers and literatures, which are very exquisite. You may wonder whether they are drawn using drawing software or office software. These are too low-end and inefficient for AI researchers, who use a number of open-source projects for neural network visualization. While each of the major deep learning frameworks provides corresponding visualization templates, they are not generalizable.

Notation Player is completely free music notation player that can run on Windows, Mac, Linux and Chromebook platforms, developed by Notation Software from Germany. It can display MIDI music files (.mid, .kar, or .not format) as sheet music, so that you can view them, print them and listen to the notes.

PictoBlox is a programming and AI education platform for kids and students, developed by STEMpedia, based on Scratch. It is essentially a third-party client for Scratch, making coding fun and easy. And it is therefore seen as the ideal companion for kids taking their first steps into the world of programming, which can help them test their ideas, learn how to import coding concepts and put everything they learn into real programs.

PicoPDF (AKA: PicoPDF PDF Editor) is a small, easy-to-use and full-featured PDF editor for Windows and Mac platforms, developed by NCH Software from Australia. The first time you use it, you will seriously doubt whether it really works. Because for a PDF editor that only has a 1M+ file size and does not rely on any components such as .NET, it's harder to implement than a PDF reader.