eMule

eMule is a free, open‑source peer‑to‑peer file sharing client for Microsoft Windows. It was released in 2002 as a fork of the eDonkey2000 project and is designed to facilitate sharing of files over the eDonkey network and Overnet, with later addition of the Kad distributed search network. The project is maintained by a community of volunteers and is distributed under the GNU General Public License.

The software connects to eDonkey/Overnet servers to locate sources and also participates in the Kad network to enable decentralized searching without servers. Users can manage download queues, download from multiple sources simultaneously, and resume interrupted transfers. eMule supports partial-file downloads, a credit-based system to encourage uploading, and various transfer optimizations. It relies on MD4 hashes to verify file integrity and to identify files across the network.

Security and usage considerations: transfers can be encrypted to some extent, but content is user‑shared, so file quality and legality depend on the sources. As with other peer‑to‑peer networks, users should exercise caution regarding copyrighted material and potential malware.

Variants and forks: a popular community fork, eMule Plus, adds user interface improvements and extra options. There are also related clients built on the same network, such as aMule for Unix-like systems, which reuse the same eD2k/Kad infrastructure.

Overall, eMule remains a historically significant Windows client in the P2P landscape, known for its configurability and network‑facing features, while facing ongoing legal and security considerations inherent to file sharing.