Given the increase in the use and profile of preprint servers – and alternative publishing hybrid platforms such as F1000 Research – in the life sciences, it is increasingly important to identify how many such servers and hybrids exist, to describe their scope in terms of the scientific disciplines they cover, and to compare and contrast their characteristics and policies. We surveyed forty-four (44) platforms that host preprints relevant to life and biomedical sciences and that were active online and accepting submissions on 25 June 2019. Information on preprint platform policies, features and practices was collected through online research by the authors and by surveying preprint platform representatives directly. Data are separated into five main tables of information and a list of preprint platform websites for reference. Table 1: Scope and ownership of each server Table 2: Content-specific characteristics and information relating to submission, journal transfer options, and external discoverability Table 3: Screening, moderation, and permanence of content Table 4: Usage metrics and other features Table 5: Metadata Preprint platform websites Data for each platform are listed as ‘Verified’ if the tables were seen and approved by a platform representative between January 13 and January 19, 2020. These data were collected in collaboration and as part of: i. An ASAPbio project, led by Dr Naomi Penfold, to develop an online directory of preprint platforms ii. A research project led by Prof Jamie Kirkham These data are supplementary outputs for both projects. Data v1.0 were presented during the ASAPbio January 2020 workshop – see Penfold, Naomi C, & Polka, Jessica. (2020, January). ASAPbio Preprint Platform Directory: 2019 data (presentation) (Version 1.0). Zenodo. http://doi.org/10.5281/zenodo.3626770.

ASAPbio (https://asapbio.org) is a scientist-driven non-profit promoting transparency and innovation in life science communication and receives funding for preprints-related work from: - The Wellcome Trust (UK) - Chan Zuckerberg Initiative (USA) - Howard Hughes Medical Institute (USA) - Simons Foundation (USA) - Medical Research Council (UK) - Canadian Institutes of Health Research (CA) Members of this group were involved in determining the practices, features and policies to survey. More information about this group is at https://asapbio.org/member-advisory-group. A Steering Group collaborating with Dr Kirkham advised on the list of platforms to survey and initial methodology: - Isabelle Boutron, INSERM, U1153 Epidemiology and Biostatistics Sorbonne Paris Cité Research Center (CRESS), Methods of therapeutic evaluation of chronic diseases Team (METHODS), Paris, F-75004 France, and Paris Descartes University, Sorbonne Paris Cité, Paris, France - John PA Ioannidis, Meta-Research Innovation Center at Stanford (METRICS), Stanford University, Stanford, CA, USA - John R Inglis, bioRxiv, Cold Spring Harbor Laboratory, NY 11724, USA The list of platforms and attributes to survey was informed by work by Martyn Rittman (open spreadsheet of preprint servers: https://docs.google.com/spreadsheets/d/17RgfuQcGJHKSsSJwZZn0oiXAnimZu2sZsWp8Z6ZaYYo/edit?usp=sharing).