Supplementary Table 3

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BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) BMJ Open

Supplementary Table 3: Submission, journal transfer options and external discoverability Preprint Server Major content Content Permitted submission formats (S) Journal submission options External content indexing (EI) / accepted (level of Language(s) Viewing options (V) Preprint displays link to journal publication (PL) Metadata availability (MA) / researcha, where Unique identifier (I; if DOI, prefix in brackets) Machine-readable full-text content known) Versioning policy / version identifiers (VP) (MR) Licensing options (L) Reader registration required to view or download full content (R) OSF Communities AfricArxiv [1] – Verified Any scholarly Afrikaans, Akan, S: PDF, Word doc, other text formats Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, content English, French, V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, Igbo, Swahili, Zulu, PDF viewable in browser without download Unpaywall other unspecified I: DOI (10.31730/osf.io) Journals directly associated with platform: None native African VP: Accepts any new versions / single DOI retained for MA: Openly available via API languages – all versions Facilitated submission to other journals: None (application programming summary must be L: Authors are provided with a choice of licenses: GNU interface) provided in English Lesser General Public License (LGPL) 3.0, BSD 3- PL: Can be added by author and French, non- Clause "New"/"Revised" License, BSD 2-Clause MR: No (planned in development English languages "Simplified" License, GNU Lesser General Public roadmap) held in moderation License (LGPL) 2.1, CC-By Attribution 4.0 queue awaiting International, Artistic License 2.0, CC0 1.0 Universal, verification Apache License 2.0, Mozilla Public License 2.0, Academic Free License (AFL) 3.0, Eclipse Public License 1.0, MIT License, GNU General Public License (GPL) 3.0, GNU General Public License (GPL) 2.0 R: No reader registration required AgriXiv [2] – Verified Research Cyrillic, English, S: Any format supported by OSF platform Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, manuscripts only Indonesian, V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, unknown if others PDF viewable in browser without download Unpaywall I: DOI (10.31220/osf.io) Journals directly associated with platform: None VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors are provided with a choice of licenses: CC0 MR: No (planned in development 1.0 Universal, CC-By Attribution 4.0 International PL: Can be added by author roadmap) R: No reader registration required Arabixiv [3] – Verified Any scholarly Arabic, English S: PDF Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, content V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, PDF viewable in browser without download Unpaywall I: DOI (10.31221/osf.io) Journals directly associated with platform: None VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors are provided with a choice of licenses: No MR: No (planned in development license, GNU Lesser General Public License (LGPL) PL: Can be added by author roadmap) 3.0, BSD 3-Clause "New"/"Revised" License, BSD 2-

Kirkham JJ, et al. BMJ Open 2020; 10:e041849. doi: 10.1136/bmjopen-2020-041849 BMJ Publishing Group Limited (BMJ) disclaims all liability and responsibility arising from any reliance Supplemental material placed on this supplemental material which has been supplied by the author(s) BMJ Open

Clause "Simplified" License, GNU Lesser General Public License (LGPL) 2.1, CC-By Attribution 4.0 International, Artistic License 2.0, CC0 1.0 Universal, Apache License 2.0, Mozilla Public License 2.0, Academic Free License (AFL) 3.0, Eclipse Public License 1.0, MIT License, GNU General Public License (GPL) 3.0, GNU General Public License (GPL) 2.0 R: No reader registration required EcoEvoRxiv [4] – All article types, English S: PDF Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, Verified datasets (primary V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, and secondary PDF viewable in browser without download Unpaywall research) I: DOI (10.32942/osf.io) Journals directly associated with platform: None VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors are provided with a choice of licenses: CC- MR: No (planned in development By Attribution-ShareAlike 4.0 International, CC-By PL: Can be added by author roadmap) Attribution-NonCommercial-NoDerivatives 4.0 International, CC-By Attribution 4.0 International, CC0 1.0 Universal, CC-By Attribution-ShareAlike 4.0 International, CC-By Attribution-NonCommercial- NoDerivatives 4.0 International, with none preferred R: No reader registration required FocUS Archive [5] – Unknown Unknown S: Any format supported by OSF platform Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, Verified V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, PDF viewable in browser without download Unpaywall I: DOI (10.31225/osf.io) Journals directly associated with platform: None VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors must use CC-BY license MR: No (planned in development R: No reader registration required PL: Can be added by author roadmap)

Frenxiv [6] – Verified All article types, Any language S: PDF, Word doc, LaTeX Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, datasets, posters (including Arabic, V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, (primary and English, French, PDF viewable in browser without download Unpaywall secondary Indonesian) I: DOI (10.31226/osf.io) Journals directly associated with platform: None research) VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors are provided with a choice of licenses: GNU MR: No (planned in development Lesser General Public License (LGPL) 3.0, BSD 3- PL: Can be added by author roadmap) Clause "New"/"Revised" License, BSD 2-Clause "Simplified" License, GNU Lesser General Public License (LGPL) 2.1, CC-By Attribution 4.0 International, Artistic License 2.0, CC0 1.0 Universal,

Apache License 2.0, Mozilla Public License 2.0, Academic Free License (AFL) 3.0, Eclipse Public License 1.0, MIT License, GNU General Public License (GPL) 3.0, GNU General Public License (GPL) 2.0, No license R: No reader registration required INA-Rxiv [7] – Verified Multiple types English, Indonesian S: PDF, Word doc, LaTeX, MarkDown Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, (including research V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, manuscripts, PDF viewable in browser without download Unpaywall essays, datasets, I: DOI (10.31227/osf.io) Journals directly associated with platform: None multimedia files; VP: Accepts any new versions / single DOI retained for MA: Openly available via API types not accepted all versions Facilitated submission to other journals: None are: thesis, report, L: Authors are provided with a choice of licenses: GNU MR: No (planned in development draft book) Lesser General Public License (LGPL) 3.0, BSD 3- PL: Can be added by author roadmap) Clause "New"/"Revised" License, BSD 2-Clause "Simplified" License, GNU Lesser General Public License (LGPL) 2.1, CC-By Attribution 4.0 International, Artistic License 2.0, CC0 1.0 Universal, Apache License 2.0, Mozilla Public License 2.0, Academic Free License (AFL) 3.0, Eclipse Public License 1.0, MIT License, GNU General Public License (GPL) 3.0, GNU General Public License (GPL) 2.0, No license, with CC-BY preferred R: No reader registration required MarXiv [8] – note: no Any scholarly Unknown S: PDF, LaTeX Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, longer on the OSF – content V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, Verified PDF viewable in browser without download Unpaywall, Altmetric, I: DOI (10.31230/osf.io) Journals directly associated with platform: None OpenChannels.org VP: Accepts any new versions / single DOI retained for all versions Facilitated submission to other journals: None MA: Openly available via API L: Authors are provided with a choice of licenses: CC-BY, CC-BY-NC-ND, No License, GNU Lesser PL: Can be added by author MR: No (planned in development General Public License (LGPL) 3.0, Eclipse Public roadmap) License 1.0, CC-BY-SA; with CC-BY preferred R: No reader registration required MetaArXiv [9] – Multiple types English S: PDF, Word doc, WordPerfect, LaTeX Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, Verified (including V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, manuscripts, PDF viewable in browser without download Unpaywall theses, conference I: DOI (10.31222/osf.io) Journals directly associated with platform: None proceedings, VP: Accepts any new versions / single DOI retained for MA: Openly available via API tutorials) all versions Facilitated submission to other journals: None L: Authors are provided with a choice of licenses: CC0 MR: No (planned in development 1.0 Universal, CC-By Attribution 4.0 International PL: Can be added by author roadmap) R: No reader registration required

MindRxiv [10] – Research English S: Any format supported by OSF platform (PDF Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, Verified manuscripts only preferred) can be published in any destination Microsoft Academic, V: By download in file format submitted by author(s), Unpaywall PDF viewable in browser without download Journals directly associated with platform: None I: DOI (10.31231/osf.io) MA: Openly available via API VP: Accepts any new versions / single DOI retained for Facilitated submission to other journals: None all versions MR: No (planned in development L: Authors are provided with a choice of licenses: CC0, PL: Can be added by author roadmap) CC-BY, no license required; with CC0 preferred R: No reader registration required NutriXiv [11] – Verified Unknown Unknown S: Any format supported by OSF platform Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, PDF viewable in browser without download Unpaywall I: DOI (10.31232/osf.io) Journals directly associated with platform: None VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors must use CC0 license MR: No (planned in development R: No reader registration required PL: Can be added by author roadmap)

OSF Preprints [12] – Multiple types Any language S: PDF, Word doc Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE Verified (including research V: By download in file format submitted by author(s), can be published in any destination articles, posters, PDF viewable in browser without download MA: Openly available via API new data) I: DOI (10.31219/osf.io) Journals directly associated with platform: None VP: Accepts any new versions / single DOI retained for MR: No (planned in development all versions Facilitated submission to other journals: None roadmap) L: Authors are provided with a choice of licenses: CC0, CC-BY, no license; with no preference for which PL: Can be added by author license chosen R: No reader registration required PaleorXiv [13] – Multiple article Any language – non- S: PDF, LaTeX, text Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, Verified types (including English languages V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, systematic reviews, held in moderation PDF viewable in browser without download Unpaywall data papers, queue awaiting I: DOI (10.31233/osf.io) Journals directly associated with platform: None methods papers) verification VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors must use CC-BY license MR: No (planned in development R: No reader registration required PL: Can be added by author roadmap)

PsyArXiv [14] – Verified Any scholarly Unknown S: PDF, Word doc Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, content V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, PDF viewable in browser without download Unpaywall I: DOI (10.31234/osf.io) Journals directly associated with platform: None VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors are provided with a choice of licenses: CC0, MR: No (planned in development

CC-BY, no license; with no preference stated PL: Can be added by author roadmap) R: No reader registration required SocArxiv [15] – Verified Research Unknown S: Any format supported by OSF platform Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, manuscripts only V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, PDF viewable in browser without download Unpaywall I: DOI (10.31235/osf.io) Journals directly associated with platform: None VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors are provided with a choice of licenses: CC0, MR: No (planned in development CC-BY, no license; with CC0 or CC-BY preferred PL: Can be added by author roadmap) R: No reader registration required SportRxiv [16] – All article types Any language – non- S: PDF Journal submission: Unrestricted - manuscript EI Google Scholar, SHARE, Verified (including research English languages V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, manuscripts, held in moderation PDF viewable in browser without download Unpaywall commentaries, queue awaiting I: DOI (10.31236/osf.io) Journals directly associated with platform: None review articles, verification VP: Accepts any new versions / single DOI retained for MA: Openly available via API current opinions, all versions Facilitated submission to other journals: None case studies, L: Authors are provided with a choice of licenses: CC0, MR: No (planned in development technical reports, CC-BY; with CC-BY preferred PL: Can be added by author roadmap) short R: No reader registration required communications) Thesis Commons [17] – Theses only Any language S: PDF, Word doc Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, Verified V: By download in file format submitted by author(s), can be published in any destination Microsoft Academic, PDF viewable in browser without download Unpaywall I: DOI (10.31237/osf.io) Journals directly associated with platform: None VP: Accepts any new versions / single DOI retained for MA: Openly available via API all versions Facilitated submission to other journals: None L: Authors are provided with a choice of licenses: CC0, MR: No (planned in development CC-BY; with no preference stated PL: Can be added by author roadmap) R: No reader registration required Open Research Central infrastructure AAS Open Research All article types English (articles) S: Word doc, RTF (Wellcome Open Research also Journal submission: Restricted - manuscript can EI: Google Scholar, PrePubMed, [18] – Verified (primary and supports LaTeX via Overleaf template) only be published in journal linked to server Europe PMC, SciLit secondary Accepts posters and V: By PDF download, full-text viewable in browser (AAS/AMRC/Gates/HRB/MNI/Wellcome Open AMRC Open Research research) slides in all without PDF (e.g. as HTML), by XML download Research, respectively) [19] – Verified languages – I: DOI (10.12688/aasopenres; …/amrcopenres; MA: Available for free upon metadata and …/gatesopenres; …/hrbopenres; …/mniopenres; PL: Yes, added by platform within one month of request Gates Open Research Editorials description must be …/wellcomeopenres) publication (AAS/AMRC/Gates/HRB/MNI); [20] – Verified (Wellcome Open in English VP: Accepts any new versions / each version receives Openly available via API Research only) its own DOI and own non-DOI citable identifier (Wellcome Open Research) HRB Open Research L: Authors must use CC-BY license [21] – Verified Posters and slides R: No reader registration required MR: Yes (XML and HTML) (AAS, AMRC, Gates

MNI Open Research Open Research [22] – Verified only)

Wellcome Open Research [23] – Verified Others arXiv [24] – Verified Research Any language – S: PDF, LaTeX, HTML Journal submission: Unrestricted - manuscript EI: Google Scholar, PrePubMed manuscripts only abstract must be in V: PDF (and other format(s) as supplied by author) can be published in any destination (q-bio only), Europe PMC, English viewable in browser without download SciLit, SHARE, INSPIRE-HEP, I: Platform-specific ID (arXiv ID) Journals directly associated with platform: None The NASA Astrophysics Data VP: Accepts any new versions / each version receives its System (ADS), The arXiv own non-DOI citable identifier Facilitated submission to other journals: Not Search Interface from the L: Authors are provided with a choice of licenses: CC0, available National Science Library, CC-BY, CC-BY-SA 4.0, CC-BY-NC-SA 4.0, non- Chinese Academy of Sciences exclusive license to distribute, any other CC license PL: Yes, added by platform after one month (also in Chinese) as specified in manuscript text; with no preference from publication for which license chosen MA: Openly available via API R: No reader registration required MR: Require full-text to be submitted in machine- readable format Authorea [25] – Any scholarly Any language S: PDF, Word doc, LaTeX Journal submission: Unrestricted - manuscript EI: SciLit, Crossref Verified content (including V: Full-text viewable in browser without PDF (e.g. as can be published in any destination articles, datasets, HTML), by LaTeX download MA: Unknown code, figures, I: DOI (10.22541) Journals directly associated with platform: None tables, slides, VP: Accepts any new versions / each version receives its MR: Yes (HTML) micropublications, own DOI Facilitated submission to other journals: Yes, and Jupyter L: Authors must use CC-BY license listed at https://support.authorea.com/en- Notebooks) R: No reader registration required us/article/how-do-i-directly-submit-to-a- publisher-atxzf7/

PL: Yes, added by platform within one month of publication

bioRxiv [26] – Verified Research English – non- S: PDF, Word doc, WordPerfect Journal submission: Unrestricted - manuscript EI: Google Scholar, Microsoft manuscripts only English language V: By PDF download, PDF viewable in browser without can be published in any destination Academic, Meta, EuropePMC, (primary research translations can be download, full-text viewable in browser without SHARE, Crossref only; white papers included as PDF (e.g. as HTML) Journals directly associated with platform: None accepted in supplementary files I: DOI (10.1101) MA: Openly available via API Scientific VP: Accepts new versions until acceptance at journal / Facilitated submission to other journals: Yes, Communication single DOI retained but new versions have distinct listed at https://www.biorxiv.org/about-biorxiv MR: Yes (HTML) and Education URLs category only; L: Authors are provided with a choice of licenses: CC0, PL: Yes, added by platform within one month of types not accepted CC-BY, CC-BY-NC, CC-BY-ND, CC-BY-NC-ND, or no publication

are: datasets, reuse; with no preference for which license chosen theses, figures, R: No reader registration required protocols, correspondence without new data or analyses) Cell Press Sneak Peekb Content criteria as Unknown S: PDF Journal submission: Manuscripts must be EI: Unknown [27] – Verified directed by V: By PDF download, PDF viewable in browser without submitted to a Cell Press Journal first, authors associated download are then provided with the option of displaying MA: Unknown journal(s) (Cell I: URL only their manuscript while under review using Press portfolio) VP: Unknown / Unknown SSRN’s ‘First Look’ (aka ‘Sneak Peek’) MR: No L: Unknown R: Reader can view basic metadata without account PL: Unknown but must register to view and download full content ChemRxiv [28] Research English S: Any (PDF) Journal submission: Unrestricted - manuscript EI: Google Scholar, EuropePMC, manuscripts only V: By PDF download, PDF viewable in browser without can be published in any destination Chemical Abstracts Services, download Crossref I: DOI (10.26434) Journals directly associated with platform: None VP: Accepts new versions until acceptance at journal / MA: Openly available via API each version receives its own DOI suffix Facilitated submission to other journals: Yes, L: Authors are provided with a choice of licenses: journals owned by American Chemical Society, MR: If provided by author in CC-BY, CC-BY-NC, CC-BY-NC-ND; with CC-BY-NC-ND Royal Society of Chemistry, German Chemical machine-readable format preferred Society (other publishers coming soon) R: No reader registration required PL: Yes, added by platform within one month of publication

ChinaXiv [29] Research Standard Chinese, S: PDF, Word doc, LaTeX Journal submission: Unrestricted - manuscript EI: ROAR (Registry of Open manuscripts only English, unknown if V: By PDF download can be published in any destination Access Repositories) other I: DOI (10.12074) VP: Accepts any new versions / single DOI retained for Journals directly associated with platform: MA: Openly available via API all versions Multiple, listed at L: Authors are provided with a choice of licenses: CC0, http://chinaxiv.org/journal/browse.htm MR: No CC-BY, CC-BY-SA, CC-BY-NC-SA; with no preference for which license chosen Facilitated submission to other journals: Not R: No reader registration required available

PL: Can be added by author or journal

ESSOAr [30] – Verified Scholarly research English S: PDF (Word and LaTeX in development) Journal submission: Unrestricted - manuscript EI: Google Scholar, SHARE, content (including V: By PDF download can be published in any destination Crossref manuscripts and I: DOI (10.1002) posters) VP: Accepts new versions until acceptance at journal / Journals directly associated with platform: 21 MA: Openly available via Crossref each version receives its own DOI suffix AGU publications (others in roadmap) L: Authors are provided with a choice of licenses: MR: Yes

CC-BY, CC-BY-NC, CC-BY-NC-ND, non-exclusive Facilitated submission to other journals: Not yet license; with no preference stated (on roadmap) R: No reader registration required PL: Yes, added by platform within one month of publication; can be added by author or journal F1000 Research [31] – Any scholarly English S: Word doc, RTF, LaTeX via Overleaf only Journal submission: Restricted - manuscript can EI: Google Scholar, Europe PMC, Verified content (including V: By PDF download, full-text viewable in browser only be published in journal linked to server SHARE, SciLit, PrePubMed articles, posters without PDF, by XML download (F1000 Research) and slides; primary I: DOI (10.12688/f1000research) MA: Openly available via API and secondary VP: Accepts any new versions / each version receives its PL: Yes, added by platform within one month of research) own DOI and own non-DOI citable identifier publication MR: Yes (XML and HTML) L: Authors must use CC-BY license R: No reader registration required JMIR Preprints [32] Research Unknown S: Word doc Journal submission: Unrestricted - manuscript EI: Unknown manuscripts, blog V: By PDF download, PDF viewable in browser without can be published in any destination posts, “grey” online download MA: Unknown reports I: DOI (10.2196/preprints.) Journals directly associated with platform: JMIR VP: Accepts first submission only / not applicable Publications journals MR: No L: Authors must use no license (all rights reserved) R: Author choice: No reader registration required, or Facilitated submission to other journals: reader can view basic content (title, abstract) Unknown without account but must register to view and download full content PL: Unknown medRxiv [33] – Verified Multiple article English S: PDF, Word doc, WordPerfect Journal submission: Unrestricted - manuscript EI: Google Scholar, Microsoft types (including V: By PDF download, PDF viewable in browser without can be published in any destination Academic Search, Crossref research articles, download systematic reviews I: DOI (10.1101) Journals directly associated with platform: None MA: Openly available via Crossref and meta-analysis, VP: Accepts new versions until acceptance at journal / clinical research single DOI retained for all versions Facilitated submission to other journals: Yes, MR: No design protocols, L: Authors are provided with a choice of licenses: CC0, listed at data articles; types CC-BY, CC-BY-NC, CC-BY-ND, CC-BY-NC-ND, or no https://www.medrxiv.org/content/about- not accepted are: reuse; with no preference for which license chosen medrxiv theses, opinion R: No reader registration required pieces, editorials, PL: Yes, added by platform within one month of narrative reviews, publication datasets) MitoFit Preprint Any scholarly English S: PDF (abstract to be submitted as Word doc) Journal submission: Unrestricted - manuscript EI: Google Scholar Archives [34] content (primary V: By PDF download can be published in any destination and secondary I: DOI (10.26124) MA: Openly available via DataCite research) VP: Accepts new versions until acceptance at journal / Journals directly associated with platform: None each version receives its own DOI suffix MR: No L: Authors must use CC-BY-NC-ND license Facilitated submission to other journals: R: No reader registration required Unknown

PL: Yes, added by platform within one month of

publication

NeuroImage: Clinical - Content criteria as Unknown S: PDF, Word doc Journal submission: Manuscripts must be EI: Unknown First Lookb [35] directed by V: By PDF download, PDF viewable in browser without submitted to the NeuroImage: Clinical first, associated journal download authors are then provided with the option of MA: Unknown (NeuroImage: I: URL only displaying their manuscript while under review Clinical) VP: Unknown / Unknown using SSRN’s ‘First Look’ MR: No L: Unknown R: No reader registration required PL: Unknown

PeerJ Preprints [36] – Any scholarly English S: PDF Journal submission: Unrestricted - manuscript EI: Google Scholar, Europe PMC Verified content (primary V: By PDF download, PDF viewable in browser without can be published in any destination and secondary download, by XML download MA: Openly available via Crossref research) I: DOI (10.7287) Journals directly associated with platform: PeerJ VP: Accepts any new versions until publication in a journals MR: No journal / each version receives its own non-DOI citable identifier Facilitated submission to other journals: L: Authors are provided with a choice of licenses: CC0, Unknown CC-BY; with CC-BY preferred R: No reader registration required PL: Can be added by author or journal

Preprints with The Content criteria as Unknown S: Unknown Journal submission: Manuscripts must be EI: Unknown b Lancet [37] – Verified directed by V: By PDF download, PDF viewable in browser without submitted to the Lancet family of journals associated download (including EBioMedicine and EClinicalMedicine) MA: Unknown journal(s) (Lancet I: URL only first, authors are then provided with the option family of journals) VP: Accepts first submission only / not applicable of displaying their manuscript while under MR: No L: Unknown review using SSRN’s ‘First Look’ R: Reader can view basic content (title, abstract) without account but must register to view and PL: Can be added by author or journal download full content

Preprints.org [38] Multiple article English S: Word doc, LaTeX Journal submission: Unrestricted - manuscript EI: Google Scholar, PrePubMed, types (including V: By PDF download can be published in any destination Europe PMC, SHARE, SciLit research I: DOI (10.20944) manuscripts, VP: Accepts any new versions / each version receives its Journals directly associated with platform: None MA: Openly available via Crossref comprehensive own DOI and own non-DOI citable identifier reviews, data L: Authors must use CC-BY license Facilitated submission to other journals: Not MR: No articles, case R: No reader registration required available reports; types not accepted are: PL: Unknown editorials, discussion papers, commentaries, coursework) Research Square [39] – Multiple article English S: Word doc, LaTeX Journal submission: Unrestricted - manuscript EI: Google Scholar, Crossref,

Verified types (including V: By PDF download, full-text viewable in browser can be published in any destination Researcher-app research articles, without PDF (e.g. as HTML) systematic reviews, I: DOI (10.21203) Journals directly associated with platform: MA: Openly available via Crossref method articles, VP: Accepts any new versions / each version receives its Submit directly or submit from BMC journals data articles; types own DOI and more from Springer Nature portfolio listed MR: Yes (HTML) not accepted are: L: Authors must use CC-BY license at https://www.researchsquare.com/journals literature reviews, R: No reader registration required hypotheses, Facilitated submission to other journals: Not opinions, theories available or commentaries) PL: Yes, added by platform within one month of publication

SciELO Preprints [40] – Research English, Portuguese, S: PDF or any PDF-convertible format Journal submission: Unrestricted - manuscript EI: Google Scholar Verified manuscripts only Spanish V: By PDF download, PDF viewable in browser without can be published in any destination download MA: Openly available via API I: URL only Journals directly associated with platform: None VP: Accepts new versions until acceptance at journal / (SciELO journals when full operation launched) MR: No single DOI retained for all versions L: Authors must use CC-BY license Facilitated submission to other journals: R: No reader registration required Available for any journal using a SWORD (Simple Web-service Offering Repository Deposit) protocol-based manuscript submission platform

PL: Can be added by author or journal

SSRN [41] – Verified Multiple types Any language – S: PDF Journal submission: Unrestricted - manuscript EI: Unknown (including research English preferred, V: By PDF download, PDF viewable in browser without can be published in any destination manuscripts, title and abstract download MA: Unknown abstracts, must be provided in I: DOI (10.2139) Journals directly associated with platform: None editorials, opinion English, non-English VP: Accepts any new versions / unknown MR: No papers) translations can be L: Unknown Facilitated submission to other journals: Not submitted and R: No reader registration required available linked to English version PL: Unknown Surgery Open Science – Content criteria as Unknown S: Unknown Journal submission: Manuscripts must be EI: Unknown b First Look [42] – directed by V: By PDF download, PDF viewable in browser without submitted to Surgery Open Science first, authors Verified associated journal download are then provided with the option of displaying MA: Unknown (Surgery Open I: URL only their manuscript while under review using Science) VP: Unknown SSRN’s ‘First Look’ MR: No L: Unknown R: Reader can view basic content (title, abstract) PL: Unknown without account but must register to view and download full content Therapoid [43] – Research English – Chinese S: PDF Journal submission: Unrestricted – manuscript EI: Not indexed

Verified manuscripts only also to be V: By PDF download, PDF viewable in browser without can be published in any destination (multimedia supported in future download MA: Openly available via Crossref content accepted in I: URL only Journals directly associated with platform: None associated VP: Accepts any new versions / each version receives its MR: No (plan to require HTML in discussion forum) own DOI Facilitated submission to other journals: Not future) L: Authors must use CC-BY license available yet (to be provided for any and only R: No reader registration required open access journals)

PL: Yes, added by platform within one month of publication

ViXra [44] Multiple types Any language – S: PDF Journal submission: Unrestricted - manuscript EI: Not indexed (including research English preferred, V: By PDF download, PDF viewable in browser without can be published in any destination articles, books, non-English download MA: Unknown theses) translations can be I: URL, Platform-specific ID Journals directly associated with platform: None provided with VP: Accepts any new versions / each version retains ID MR: No English version, as with a version number Facilitated submission to other journals: Not new versions or L: Authors can use any license available submitted R: No reader registration required separately PL: Can be added by author or journal

a Where primary research is research based on empirical data and secondary research is derived from primary research, such as literature reviews and meta-reviews; b See SSRN for general platform information

Preprint platform websites

1. AfricArxiv https://info.africarxiv.org/ 23. Wellcome Open Research https://wellcomeopenresearch.org/ 2. AgriXiv https://agrixiv.org 24. arXiv https://arxiv.org 3. Arabixiv https://arabixiv.org/ 25. Authorea https://www.authorea.com 4. EcoEvoRxiv https://ecoevorxiv.org 26. bioRxiv https://www.biorxiv.org/ 5. FocUS Archive https://osf.io/preprints/focusarchive/ 27. Cell Press Sneak Peek https://papers.ssrn.com/sol3/Jeljour_results.cfm?form_name=journalBrowse&journal_id=3184889 6. Frenxiv https://frenxiv.org 28. ChemRxiv https://chemrxiv.org 7. INA-Rxiv https://osf.io/preprints/inarxiv 29. ChinaXiv http://chinaxiv.org 8. MarXiv https://marxiv.org 30. ESSOAr https://www.essoar.org 9. MetaArXiv https://osf.io/preprints/metaarxiv/ 31. F1000 Research https://www.essoar.org 10. MindRxiv https://mindrxiv.org 32. JMIR Preprints https://preprints.jmir.org/ 11. NutriXiv https://osf.io/preprints/nutrixiv 33. medRxiv https://www.medrxiv.org 12. OSF Preprints https://osf.io/preprints/ 34. MitoFit Preprint Archives https://www.mitofit.org/index.php/MitoFit_Preprint_Archives 13. PaleorXiv https://paleorxiv.org 35. NeuroImage: Clinical – First Look https://papers.ssrn.com/sol3/JELJOUR_Results.cfm?form_name=journalBrowse&journal_id=3178959 14. PsyArXiv https://psyarxiv.com 36. PeerJ Preprints https://peerj.com/preprints/ 15. SocArXiv https://osf.io/preprints/socarxiv 37. Preprints with The Lancet https://papers.ssrn.com/sol3/JELJOUR_Results.cfm?form_name=journalBrowse&journal_id=3184962 16. SportRxiv https://osf.io/preprints/sportrxiv 38. Preprints.org https://www.preprints.org/ 17. Thesis Commons https://thesiscommons.org 39. Research Square https://www.researchsquare.com 18. AAS Open Research https://aasopenresearch.org/ 40. SciELO Preprints https://preprints.scielo.org/index.php/scielo 19. AMRC Open Research https://amrcopenresearch.org/ 41. SSRN https://www.ssrn.com 20. Gates Open Research https://gatesopenresearch.org/ 42. Surgery Open Science – First Look https://papers.ssrn.com/sol3/Jeljour_results.cfm?form_name=journalBrowse&journal_id=3303309 21. HRB Open Research https://hrbopenresearch.org/ 43. Therapoid https://therapoid.net 22. MNI Open Research https://mniopenresearch.org/ 44. ViXra http://vixra.org

Kirkham JJ, et al. BMJ Open 2020; 10:e041849. doi: 10.1136/bmjopen-2020-041849