"Find 100+ million publication pages, 15+ million researchers, and 700k+ projects. ResearchGate is where you discover scientific knowledge and share..."
Note: This is a research productivity free service; a subscribed members expose their work to a world-wide community of researchers; are able to network with other researchers; read and discuss publications; and they get in-depth stats impact of their publications as well can keep track of their citations.
Academia.edu is a place to share and follow research. "Academia is the easiest way to share papers with millions of people across the world for free. A study published in PLOS ONE found that papers uploaded to Academia receive a 69% boost in citations over 5 years".
Note: This is a research productivity free service with the option of a for fee upgraded version.
"Mendeley is a free reference manager and an academic social network. Manage your research, showcase your work, connect and collaborate …"
Note: A free account provides with very good basic options reference management. It also serves as a Research productivity service to showcase your research.
Note: in addition to be a bibliographic database, the research productivity part is possible by authors creating a profile they can edit themselves. Google Scholar calculates altmetric impact.
"See what's happening in the world right now."
Note: One of the most used information network in social media. It can be used to monitor trending issues in specific research areas. Impact of researchers can also be measured.
"Welcome to LinkedIn, the world's largest professional network with more than 562 million users in more than 200 countries and territories worldwide".
Note: The strength of is users profile network. See this article: https://en.wikipedia.org/wiki/LinkedIn
"Open access to 1,476,783 e-prints in Physics, Mathematics, Computer Science, Quantitative Biology, Quantitative Finance, Statistics, Electrical Engineering and Systems Science, and Economics."
"arXiv is owned and operated by Cornell University, a private not-for-profit educational institution. arXiv is funded by Cornell University Library, the Simons Foundation and by the member institutions".
Note: This is an open access pre-print repository usually mined by almetrics projects and also incorporated in open databases such as BASE, Dimensions and other. Excellent platform for exposure and therefore is considered a research productivity source.
"Scitation is home to the most influential news, comment, analysis and research in the Physical Sciences."
Note: It is a research productivity service with free subscription. It includes the following organizations:
AIP Publishing - American Institute of Physics; Acoustical Society of America; American Association of Physics Teachers; American Crystallographic Association; AVS: Science & Technology of Materials, Interfaces, and Processing; Chinese Physical Society; Laser Institute of America; and the Society of Rheology.
"Who's talking about your research? Thousands of conversations about scholarly content happen online every day. Altmetric tracks a range of sources to capture and collate this activity, helping you to monitor and report on the attention surrounding the work you care about."
Note: Impact of productivity can be explore with a project=based free subscription. Institutional fee based subscription is also available.
Amazon Author Central
Note: with a free author's profile you can communicate about your books to a wide-audience.
"Citeulike is a free service for managing and discovering scholarly references. 8,755,326 articles - 634 added today." (12-12-18)
"Easily store references you find online. Discover new articles and resources. Automated article recommendations. Share references with your peers. Find out who's reading what you're reading. Store and search your PDFs".
Note: Both, a productivity free service and a bibliographic database, uses social bookmarking for sharing references. See article: CiteULike at https://en.wikipedia.org/wiki/CiteULike
"GitHub is a development platform inspired by the way you work. From open source to business, you can host and review code, manage projects, and build software alongside 31 million developers".
Note: a good collaborative site ideally to expose and share your code.
"ReadCube - Reference & citation manager for article PDFs"
Note: partners: IoP, Wiley, Emerald Publishing, Springer Nature, MIT Press, Taylor & Francis, and the Royal Society of Chemistry. See article ReadCube at: https://en.wikipedia.org/wiki/ReadCube. It is a research productivity services with free subscription. They also develop products for publishers.
"Your personal research assistant. Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research".
Note: A free account provides with very good basic options reference management. It also serves as a Research productivity service to showcase your research. See this article: https://wac.colostate.edu/books/infolit/chapter14.pdf