There are so many interesting and useful video resources on YouTube, such as a variety of free courses, tutorials, or music videos. Most of us maybe want to download them or convert them into audio files for offline viewing and listening in the future. However, YouTube has never allowed users to download their videos, let alone saving them as audio files.

Moo0 Mp3 Converter (formerly called Moo0 Audio Converter, Moo0 Audio Type Converter) is a very practical audio format conversion and extraction tool, supports the conversion between various audio formats (including 3GP, AAC, AC3, AIFF, AMR, AU, FLAC, M4A, MOV, MP3, MP4, RA, RM, WAV, WMA, PCM, and so on). Better yet, it's completely free and pretty easy to use.

Pichon is an icon client software that allows to drag its icons directly to any software to use, developed by Icons8. It includes a huge collection of icons (160000+ so far) from Icons8, all of which are free to use. These icons come with a variety of types, formats, colors, and sizes. Thereinto, the PNG and SVG formats can be instantly recolored according to your need.

Xojo is an unpopular but interesting integrated development environment for cross-platform applications. It can write native applications (that is, executable files in various formats that consist of instructions that can be executed directly by the CPU) with a graphical user interface for various operating systems and platforms (desktop, mobile, web and Raspberry Pi), as well as console applications, background service applications and web applications that do not have a graphical user interface.

Mind map (also known as mental mapping) is a simple yet effective and revolutionary graphical thinking tool that is used to express our divergent thinking. And the mind mapping tool is like a digital alternative of the traditional memo, wall map or whiteboard, with which you can organize brainstorming, capture ideas, communicate and plan information just through a single view.