Mushroom Observer is a collaborative mycology website started by Nathan Wilson in 2006.

[2] The community of about 12,000 contributing users collaborates on identifying the submitted mushroom images, assigning their scientific names by means of a weighted voting process.

All photographs are subject to a Creative Commons license that allows their reuse by others without the need for remuneration or special permission, subject to the terms of the license.

[2] The software is open source and hosted on GitHub.

[2] As of 2024, the website contains about half a million user-submitted mushroom observations illustrated by more 1.6 million photographs of nearly 20,000 species of fungi.