Freesound

An open-source mathematics textbook project dedicated to promoting educational equity, offering PDF resources from primary school to university levels. It features automated merging of split PDF files, serving families and students worldwide.

FLVTO is the best search engine and the MP3 & MP4 download website. Using this site Download high quality YouTube MP3 & MP4 fast, easy and free in just a few clicks. It does not require installation of software and application

Z-Library - 保持与全球最大的电子书图书馆联系。免费查找并下载电子书。官方Z-Library。

跨平台视频提取工具：支持流媒体下载、视频下载、m3u8 下载及 B站视频下载，提供 Windows 和 Mac 桌面客户端。Cross-platform video extraction tool: Supports streaming download, video download, m3u8 download, and Bilibili video download, with desktop clients for Windows and Mac.