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With this popularity, the public digital traces of GitHub are now a valuable means to study teamwork and collaboration. In many ways, however, GitHub is a convenience sample, and may not be representative of open source development off the platform. Here we develop a novel, extensive sample of public open source project repositories outside of centralized platforms. We characterized these projects along a number of dimensions, and compare to a time-matched sample of corresponding GitHub projects. Our sample projects tend to have more collaborators, are maintained for longer periods, and tend to be more focused on academic and scientific problems.<\/jats:p>","DOI":"10.1140\/epjds\/s13688-022-00345-7","type":"journal-article","created":{"date-parts":[[2022,5,21]],"date-time":"2022-05-21T11:03:04Z","timestamp":1653130984000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["The penumbra of open source: projects outside of centralized platforms are longer maintained, more academic and more collaborative"],"prefix":"10.1140","volume":"11","author":[{"given":"Milo Z.","family":"Trujillo","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laurent","family":"H\u00e9bert-Dufresne","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4614-0792","authenticated-orcid":false,"given":"James","family":"Bagrow","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2022,5,21]]},"reference":[{"issue":"10","key":"345_CR1","doi-asserted-by":"publisher","first-page":"29","DOI":"10.1145\/3183558","volume":"61","author":"JF Abramatic","year":"2018","unstructured":"Abramatic JF, Di\u00a0Cosmo R, Zacchiroli S (2018) Building the universal archive of source code. 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