With over 50 million observations per year, iNaturalist is one of the world's most successful citizen science projects, uniting millions of people worldwide in observing, sharing, and identifying nature (Mason et al. 2025). iNaturalist and Wikipedia have much in common: they are both collaborative, large-scale, open infrastructures made by volunteer communities with long-reaching impact on human knowledge. Wikipedia and its sister projects, Wikimedia Commons and Wikidata, also influence biodiversity research worldwide via their numerous, widely-accessed entries on nature topics (Lubiana 2025).<br> While contributions to both projects are primarily made by individual volunteers, a community of iNaturalist contributors that first convened at Wikimania 2018, a Wikimedia conference in Cape Town, South Africa, started WikiProject Biodiversity. The coordinated contributors facilitate content flow in three main ways: by directly adding content to iNaturalist and sharing it on Wikimedia projects, by supporting the development of tools, and by promoting campaigns and outreach activities (for example, by participating at Living Data 2025, in Bogotá, Colombia). To enable the seamless upload of iNaturalist images to Wikimedia Commons (which in turn enables their reuse on Wikipedia and other Wikimedia projects), this volunteer community has developed a diverse set of open source tools, detailed in Table 1. These volunteer-driven tools are released under open source licenses, making it possible for anyone to join, contribute and expand on the work.<br> <br> While there is no formal content partnership between iNaturalist and the Wikimedia Foundation, the volunteer community that connects the two platforms follows a similar pattern as GLAM<br> <br> (Galleries, Libraries, Archives and Museums) partnerships in Wikimedia. This ensures that iNaturalist content on Wikimedia enjoys a wealth of resources for tracking and reporting impact, including statistics for uploads and page views. Using Wikimedia's open Commons Impact Metrics API, we can identify over 220,000 images on Wikimedia Commons sourced from iNaturalist. A fourth of those images (around 53,000) are reused to illustrate content on Wikimedia projects (such as English Wikipedia). On average, iNaturalist images receive around 27 million monthly views across Wikimedia platforms (as of August 2025). When these images make it to the English Wikipedia main page, views may go as high as 196 million in one month, which was the count for May 2025 (Fig. 1).<br> <br> iNaturalist content also finds its way into the Wikimedia ecosystem via Wikidata, a collaboratively edited multilingual knowledge graph, which also has members engaged with biodiversity informatics (Groom and Paul 2020, von Mering et al. 2025). Wikidata currently holds five kinds of iNaturalist identifiers: place, taxon and user IDs enrich information on Wikidata, while photo and observation IDs contribute to structured metadata on Commons. This infrastructure supports and enriches iNaturalist itself, as the platform relies on Wikidata links to select Wikipedia content as the default description of taxon pages.<br> To sum up, we invite the reader to join the community of iNaturalist contributors and Wikimedians: there are a countless ways that biodiversity lovers can join and support this work (von Mering et al. 2025, Meudt and Leachman 2025). By uploading iNaturalist photos, joining WikiProject Biodiversity, and licensing your photos as CC0, CC-BY or CC-BY-SA, you will be joining a welcoming community, and helping to expand the free (as in freedom) biodiversity knowledge on the internet.
