Introduction
The exponential growth in volume, complexity, and diversity of scientific datasets presents mounting challenges for the integrity of scientific records and for the global research community creating them. Data repositories must continually adapt to evolving technologies, user expectations, and the demands of integrating data with publications, software, and other research outputs. Increasingly, researchers are required to make their data accessible and deposit it in trustworthy repositories to meet the requirements of funders and publishers. These evolving expectations underscore the need for robust infrastructures that promote scientific rigor and facilitate responsible sharing of data. In this context, repository trustworthiness is not an abstract attribute; it is defined through demonstrable compliance with explicit criteria for integrity, transparency, sustainability, and accountability. Communities engaged in data management have long been at the forefront of addressing ever-evolving challenges by developing standards and frameworks to support trustworthy data repositories, including the creation of core certification frameworks (see Figure 1). Certification frameworks such as CoreTrustSeal (Board, 2022), nestorSeal (Network of Expertise in Long-Term Storage of Digital Resources) (Dobratz et al., 2009), and ISO 16363 (ISO 16363, 2025) operationalize trustworthiness by specifying requirements across core domains: organizational infrastructure, digital object management, security/risk management, and documentation.
Figure 1
Infographic on the origins and key criteria of nestorSeal, ISO 16363, and CoreTrustSeal certification frameworks for Trusted Digital Repositories.
These frameworks play a pivotal role by establishing standardized criteria for repository reliability and sustainability (Lockhart, Xesi and Chiware, 2024). Through independent peer review and iterative recertification processes, these frameworks foster not only accountability but also drive continuous improvement, helping the long-term accessibility, usability, and reproducibility of digital research outputs (Donaldson and Russell, 2023). Such practices are essential not only for scientific rigor but also for building public confidence in research outcomes (Donaldson and Russell, 2023; Frank, 2024) while contributing to the sustainability of open science principles (Downs, 2021).
This paper provides new insights by drawing on the experiences of a global community deeply engaged in data curation at the gateway of scientific data sharing. The study was conducted under the mandate of the Scientific Committee of the World Data System (WDS) and its Subcommittee on Standards and Certifications. It presents findings from two complementary approaches: (1) a global survey of repository representatives, which gathered input from data repository representatives, and 2) a comparative analysis of major certification frameworks, including CoreTrustSeal, nestorSeal, and ISO 16363. By examining different certification pathways for data repositories, specifically as they relate to access to WDS Membership (see Figure 2), the authors explored avenues to lower barriers for diverse repositories seeking to join the science data repository community without compromising rigorous standards of trustworthiness. While this study was originally tailored to WDS membership criteria, the challenges and solutions explored can also offer useful perspectives for other organizations addressing similar issues in trustworthy data stewardship.
Figure 2
Infographic on WDS mission statement and global member distribution by membership type.
Methods
To comprehensively evaluate certification practices and identify potential pathways for inclusivity, we used a mixed-methods approach by means of (1) a comparative analysis of existing certification frameworks and (2) surveying the repository community for direct feedback. By combining systematic assessment of standards with empirical insights from practitioners, this approach provides a holistic understanding of both formal requirements and real-world challenges faced by repositories seeking trustworthy status. It directly supports WDS’ objectives to support its member repositories and to advocate for quality, trustworthiness, equitability, and FAIRness of data and data repositories worldwide (World Data System, 2025).
1. Certification Frameworks Review
To assess global standards for trustworthy digital repositories, the authors conducted a comparative analysis of certification frameworks, focusing on overlapping requirements and distinctive features (see Appendix A). Certification frameworks were selected based on their relevance to international standards for trustworthy digital repositories and their prominence within the research data management community. The initial selection included CoreTrustSeal Requirements (2023–2025), ISO 16363: 2025, and the nestorSeal. Importantly, additional frameworks were incorporated following recommendations from survey participants, ensuring the analysis reflects both established standards and community-driven priorities. These additional recommendations from survey respondents were Trustworthy Repositories Audit and Certification (TRAC) (Ambacher et al., 2007), the US Department of Energy (DOE) Office of Science (SC) Public Reusable Research (PuRe) designation (Kung, 2021), and OpenAIRE guidelines (OpenAire, n.d.). Except for TRAC, these additional standards are not considered certification frameworks and were therefore excluded from the comparative analysis; however, they are briefly discussed in the Results section for completeness.
2. Survey
Informal feedback from WDS member and non-member repositories regarding challenges with CoreTrustSeal certification processes provided impetus to address the issues through an organized data collection. We designed a survey to gather insights into current certification practices among data repositories globally. The survey (see Appendix B) aimed to identify commonly used certifications while exploring avenues for extended certification pathways that could foster a more inclusive repository community. It targeted international certifications, funder-mandated accreditation processes, and disciplinary-specific standards related to trustworthy digital repositories rather than interoperability protocols. It was disseminated through multiple channels, including WDS social media platforms, newsletters, and partnerships with organizations such as the Research Data Alliance (RDA), International Science Council (ISC), and ISC’s Committee on Data (CODATA).
The survey remained open for 9 weeks and collected 64 valid responses using Qualtrics software. Ethical compliance was ensured through Institutional Review Board (IRB) approval at the University of Tennessee, Knoxville (#UTK IRB-24-08222-XM; approval date: June 28, 2024).
Data Availability
The survey data generated and analyzed during this study have been deposited in Dryad and are openly available at https://doi.org/10.5061/dryad.dz08kps8c (Santos Oliveira et al., Forthcoming 2025).
Results
The results of the current work describe key findings from the comparative analysis of certification frameworks and insights gathered from the repository community through the survey.
1. Certification Frameworks Review
The criteria listed in each certification (CoreTrustSeal, nestorSeal, ISO 16363) were compared side by side to identify overlapping requirements and distinctive features. Shared values in digital preservation emerged across frameworks, revealing fully overlapping essential minimal requirements for trustworthiness: Organizational Infrastructure, Digital Object Management, and Information Technology and Security. Additionally, an assessment of the historical journeys of these groups (see Figure 1) illustrates the community’s convergence around standards for trustworthiness and its members’ sustained commitment to adapting certification criteria as technologies, policies, and user needs change. This convergence illustrates how many certification frameworks came to be grounded in a similar set of foundational requirements, emphasizing transparency, accountability, compliance, and sustainability.
The differences between the frameworks in analysis here were at the next level of granularity–residing in the number of metrics or quantifiable indicators used to evaluate each key requirement, with ISO 16363 requiring the largest number of metrics (see Appendix A). These differences lie mostly in the scope, depth, and approach to audit and compliance: CoreTrustSeal offers a streamlined, entry-level certification with concise, practical requirements assessed via an initial self-review followed by peer-review; ISO 16363 stands out as an international standard requiring formal external audits and comprehensive documentation; and nestorSeal mostly adapts global standards to the German context, emphasizing stakeholder engagement and national priorities. Thus, although all frameworks share foundational requirements for organizational infrastructure, digital object management, and security/risk management, they diverge significantly in their audit methodologies and the extent of measurable criteria applied.
In addition to the initial certifications and guidelines identified for this study, the authors researched some of the additional recommendations from survey respondents. These guidelines for trustworthy repositories include TRAC, DOE’s PuRe, and OpenAIRE Guidelines.
The TRAC certification system, administered by the Center for Research Libraries (CRL), was created in 2007 through a collaboration between CRL, the Research Libraries Group (RLG), the National Archives and Records Administration, and the Consultative Committee for Space Data Systems. TRAC provided a framework for assessing digital repositories based on best practices in digital preservation and adherence to the OAIS Model (Yakel, 2007). In 2012, TRAC evolved into ISO 16363 (CCSDS, 2024), an international standard for evaluating the trustworthiness of digital repositories. Since CRL suspended its audit work in 2014, ISO 16363 certifications have been issued exclusively by the Primary Trustworthy Digital Repository Authorisation Body (PTAB).
PuRe is an initiative to increase the accessibility and reuse of research data produced through the U.S. DOE Office of Science-funded projects. It supports open access to scientific data, encouraging collaboration, innovation, and discovery across the research community. PuRe responds to the growing demand for effective data sharing and reuse, which is essential for driving scientific progress and tackling complex challenges in fields such as energy, environmental science, and materials research. PuRe is only available for DOE-funded projects. OpenAIRE is a non-profit organization and is an implementor of the European Open Science Cloud (EOSC) (Bertelli, Acciai and Rossi, 2025). The OpenAIRE guidelines aim to ensure the FAIRness and interoperability of data in the EOSC. As such, they are not a standard.
2. Survey
Global Reach of Survey
Representatives from 64 repositories participated in the survey; 55% of the represented repositories were not WDS members, while the remaining 45% were affiliated with WDS. The respondents were globally distributed, as seen in Figure 3.
Figure 3
Representatives from 64 repositories participated in the survey. Their geographical distribution is depicted here in percentage (N=64).
CoreTrustSeal Prevalence
The survey included questions that were intended to assess the current landscape regarding CoreTrustSeal certification among participating repositories. This evaluation is significant because CoreTrustSeal certification is widely encouraged (and in many cases required) by leading organizations such as the WDS and others as a mark of trustworthiness for data repositories. At the same time, CoreTrustSeal is recognized as one of the more attainable certification frameworks, offering a pragmatic pathway for repositories seeking to demonstrate compliance with best practices and community standards (Dillo and de Leeuw, 2018). A key objective of this study is to analyze the broader environment of certification practices within the global data repository community. Therefore, understanding both the prevalence and status of CoreTrustSeal certification and gaining insights into repositories’ experiences with the application process provides important context for evaluating the present certification scenario.
The data revealed that 40.6% of respondents had never held CoreTrustSeal certification, while 25% are currently certified. Additionally, 18.8% of repositories were working on their application, and 15.6% had either allowed their CoreTrustSeal certification to lapse or were in the process of renewal (see Figure 4). Among those whose certification had expired, 80% planned to renew, whereas 20% were uncertain or did not intend to pursue renewal.
Figure 4
Count by status of CoreTrustSeal (CTS) certification among data repository survey respondents (N=64).
To better understand the experiences with CoreTrustSeal certification, respondents who had interacted with CoreTrustSeal (N = 38) were asked to identify the main challenges they faced when applying for or renewing CoreTrustSeal certification. The challenges listed in the survey included time commitment, organizational effort, and expense associated with the application process (see Figure 5). Other issues listed by survey respondents were the length and complexity of the review process, inconsistencies among reviewers and review phases, administrative hurdles resulting from system changes, documentation of repository protocols, collaboration with IT departments, the lack of official national documents on long-term repository support, and varying interpretations of requirements.
Figure 5
Count of challenges encountered during the application or renewal processes of CoreTrustSeal certification. The selection of multiple options was enabled to allow respondents to indicate all the possible problems encountered (N=64).
Certification Landscape
In addition to examining experiences with CoreTrustSeal, it was important to understand the broader certification landscape. Respondents were asked to report on any other certifications or standards their repositories may be required to obtain due to national regulations or funder stipulations, whether at a national level or within their field. 64% of the respondents reported no such requirements, 23% responded yes, and 13% were unsure (see Figure 6).
Figure 6
Percentage of respondent repositories with accreditations or certifications mandated by local governments or funding agencies (N=64).
The survey addressed an important policy question for any organization that requires certification. This was asked in the context of WDS (that requires CoreTrustSeal certification for membership): “Should repositories certified under frameworks other than CoreTrustSeal be eligible for WDS membership?” 55% responded affirmatively (see Figure 7). However, when asked which alternative certifications or accreditations should be considered, 62% did not respond, 14% were unsure or unaware of other options, and only 23% provided suggestions. Among the recommendations were ISO 16363, nestorSeal, the US DOE SC PuRe Data Resource, NASA data centers, Data Quality Assessment, and OpenAIRE, some of which are no longer available, nor certification processes, but rather checklists of best practice guidelines.
Figure 7
Responses to the survey question on whether other certifications (besides CoreTrustSeal) should be allowed for WDS membership. Responses are presented in percentage (N=64).
Discussion
Building on these results and their implications for the global community of trustworthy data repositories committed to best practices in data stewardship, this discussion focuses on how evolving certification standards not only influence organizational criteria but also foster greater inclusivity and shape the broader landscape of trustworthy scientific data repositories across diverse research domains.
Certification Frameworks Review: Comparative Analysis
Our comparative analysis of certification frameworks (CoreTrustSeal, nestorSeal, ISO 16363) revealed significant alignment in their foundational requirements for trustworthy digital repositories. Across all frameworks, the core pillars of trustworthiness: Organizational Infrastructure, Digital Object Management, and Information Technology and Security, were consistently emphasized. This convergence reflects the shared values in digital preservation that underpin these certifications. The primary distinction lies in the granularity of evaluation metrics, with ISO 16363 using the most extensive set of quantifiable indicators to assess compliance.
While PuRe and OpenAIRE guidelines are not certifications, they play an important role in promoting best practices in digital preservation. As such, both initiatives should be recognized as steps toward implementing good practices in data stewardship. By fostering adherence to these principles, they contribute to the broader goal of ensuring trustworthiness and sustainability in scientific data infrastructures.
Survey Outcomes
1. Global Participation and Interest
The widespread participation in the survey underscores the broad geographical spread of science data repositories and a global interest in certification, while highlighting challenges faced by repositories across different regions. A landscape analysis conducted by the FIDELIS project indicates similar challenges experienced by European repositories (Wittenburg et al., 2006). Both studies signal an active community ready for improvements in existing certification frameworks.
2. Membership Status and Certification Hurdles
The geographical distribution of respondents showed a notable number of WDS non-members (55%) participating in the survey. The authors interpret this as a sign that many repositories are keen to join this conversation, and many face hurdles related to certification regardless of their WDS membership.
3. CoreTrustSeal Certification Status
Survey respondents continue to support CoreTrustSeal as a certification standard, expressing concerns about the potential fragmentation that could arise from the proliferation of alternative standards. At the same time, there is a clear disconnect between the community’s recognition of repositories progressing toward improved performance and the hurdles identified by respondents in the certification process. This highlights the need for coordinated community support and more flexible pathways to certification.
Additionally, the data revealed that while most WDS member respondents hold a valid certification, many had allowed theirs to lapse or were in the process of renewal. This mixed response highlights varying capacities and motivations across repositories, emphasizing the need for more flexible and supportive pathways to certification renewal.
4. Certification Challenges
There are challenges to certification. CoreTrustSeal, a primary certification framework, provides insight into challenges that repositories may face during a certification process. These challenges include the level of time commitment, organizational effort, and financial costs. There was also some concern about the complexity of the review process, inconsistencies among reviewers, administrative hurdles, documentation requirements, collaboration with IT departments, lack of national support documents, and varying interpretations of requirements. These challenges indicate directions in which additional support or process streamlining could help science data repositories manage any certification process.
5. Alternative Certifications
WDS was interested in how members regarded the requirement for every member repository to have certification. 55% of the participating repository representatives indicated that they would accept alternative trustworthy frameworks rather than specifying only one. However, there was a lack of consensus on which alternatives to offer.
Outcomes and Strategic Actions Toward Broadening Certification Practices
The WDS is a community of trustworthy digital repositories that provide vital infrastructures for scientific collaboration, open science, and AI-enabled science. Recognizing the barriers faced by repositories, including complex certification processes, evolving technologies, and increasing demands for data accessibility, WDS recommends that the science data community take decisive steps to address these challenges through innovative strategies that promote inclusivity, trustworthiness, and sustainability.
These are actionable recommendations aimed at enhancing repository services, fostering equitable access to membership frameworks, and amplifying repositories’ contributions to advancing science for societal benefit. These recommendations not only reflect WDS’s commitment to strengthening its leadership role in data governance but also underscore its dedication to empowering repositories worldwide to serve as role models for the broader community.
By implementing these recommendations, WDS aims to ensure that its members exemplify the best practices in data stewardship and inspire other repositories to follow suit. The actions outlined below are designed not only to benefit WDS members but also to position them as leaders who set the standard for inclusivity, trustworthiness, and sustainability across the global repository ecosystem.
Recommendation 1: Expand Recognition of Trustworthy Certification Frameworks for WDS Member Data Repositories
To promote inclusivity while upholding rigorous standards, the WDS research data community should recognize a wider range of internationally accepted certification frameworks, such as CoreTrustSeal, nestorSeal, and ISO 16363, as valid indicators of repository trustworthiness. By broadening the criteria for trustworthiness status and membership within professional networks, organizations can attract a diverse array of repositories and enhance transparency and visibility across the global data ecosystem.
Recommendation 2: Support Progressive Pathways Toward Trustworthiness
To further inclusivity and encourage participation from repositories at different stages of development, the research community should establish pathways that recognize measurable progress toward trustworthy practices, not just immediate attainment of full certification. Acknowledging continuous improvement and incremental achievements helps lower barriers to entry, supports repositories with varying resources, and maintains a commitment to high standards while fostering global diversity in data stewardship.
Recommendation 3: Strengthen Funding Agency Engagement
Ensuring sustainable certification pathways for trustworthy data repositories requires proactive collaboration between repositories, professional networks, and research funding agencies. Funders should not only require data deposit into trustworthy repositories, but also provide the resources, infrastructure, and guidance necessary for repositories to achieve and maintain certification. Aligning funding mechanisms with repository needs, including incorporating certification costs into grant proposals, will help secure the long-term impact and reliability of scientific data stewardship.
To facilitate these partnerships, organizations, like WDS, can:
Develop targeted support materials (e.g., fact sheets, value letters, tailored presentations) that communicate the importance and benefits of repository trustworthiness to funders.
Organize workshops and training sessions to equip repository staff with skills to effectively articulate their value narratives and demonstrate the impact of certification.
By fostering mutual understanding and support between repositories and funders, the community can ensure that certification is both attainable and sustainable, ultimately strengthening the global infrastructure for trustworthy data sharing.
Recommendation 4: Expand Stakeholder Messaging to Highlight the Broader Value of Trustworthy Data Repositories
To strengthen engagement among researchers, funders, and policymakers, the research data community should expand compliance-focused messaging to encompass narratives that emphasize the wider benefits of data sharing. Instead of centering communications solely on meeting requirements, this approach frames trustworthy data repositories as essential infrastructures that enable scientific collaboration, foster transparency, and drive societal advancement. By articulating how repositories support co-creation and impactful research outcomes, organizations can build stronger stakeholder commitment and elevate the perceived value of trustworthy data stewardship.
To implement this expansion, organizations, like WDS, can:
Develop evidence-based narratives supported by compelling success stories that demonstrate the real-world impact of trustworthy data sharing.
Collaborate with respected leaders in open science, data stewardship, or related domains, such as community advocates, funding agency representatives, or recognized experts, to endorse and amplify key messages.
Adopting this messaging strategy will help position trustworthy repositories not only as compliance solutions but as vital enablers of collaborative, transparent, and impactful science.
Recommendation 5: Enhance Equitable Access to Certification for Data Repositories
To promote fairness and inclusivity in repository certification, organizations like WDS are especially positioned to provide research data repositories with practical guidance and support throughout the certification process. Collaboration with certifying bodies can help advocate for cost-effective solutions, including:
Banded fee structures based on country income levels, reducing economic barriers, and supporting global diversity.
Differentiated cohort application and renewal fees that reflect varying levels of effort and resources required, especially during recertification.
Tailored training programs that equip repositories with the necessary knowledge and tools to achieve and maintain trustworthiness standards.
By lowering financial and informational barriers, the community enables a broader range of science data repositories, regardless of geographic or economic context, to pursue and sustain rigorous standards of trustworthiness.
Recommendation 6: Promote Funding Cohorts to Advance Repository Certification in LMICs
To promote equity in global open science, the research data community should encourage funding agencies to provide targeted support for trustworthy data repositories in low- and middle-income countries (LMICs). Beyond mandating data deposit policies, funders play a critical role in enabling repositories to attain certification and develop sustainable infrastructure for long-term stewardship. Establishing cohorts of candidate repositories through tailored funding models can strengthen capacity, foster collaboration, and advance equitable participation in open science ecosystems.
Actions the wider community and organizations like WDS can take to implement this recommendation include:
Developing practical guidance documents to help repositories identify funding opportunities, with lists of potential funders and approaches tailored to LMIC contexts.
Advocating for sustained infrastructure investment by showcasing the long-term impact of funded cohorts on scientific collaboration and societal progress.
Organizing specialized training sessions and mentorship programs for LMIC repositories to build skills and readiness for certification.
By investing in cohort-based support and capacity-building initiatives, the community can help bridge existing gaps, ensuring that all regions have pathways to participate fully in trustworthy data stewardship.
Conclusion
This study demonstrates that global certification frameworks for trustworthy digital repositories, such as CoreTrustSeal, nestorSeal, and ISO 16363, share foundational requirements and values in digital preservation yet vary in implementation detail. By engaging with the repository community and analyzing survey responses, we have identified alternative certification pathways that can promote greater inclusivity, accessibility, and diversity within the research data ecosystem. The actionable recommendations outlined here highlight the need to strengthen engagement with funding agencies, shift stakeholder messaging toward broader value narratives, provide robust certification support, and advance targeted funding for data repository infrastructures worldwide, particularly in LMICs. As organizations, including but not limited to WDS, advance these strategies, the global open science community moves toward a more equitable, sustainable, and interconnected ecosystem in which trustworthy repositories can thrive and drive scientific progress for societal benefit.
Additional Files
The additional files for this article can be found as follows:
Appendix A
Table 1 - Summary of Review Criteria Across Repository Certification Frameworks. DOI: https://doi.org/10.5334/dsj-2026-016.s1
Appendix B
WDS’ Subcommittee on Standards and Certifications – SURVEY. DOI: https://doi.org/10.5334/dsj-2026-016.s2
Author Contributions
David Castle, Ioana Popescu, Claudia Bauzer Medeiros, and Dale Peters conceived the study idea. Ioana Popescu, Dale Peters, Claudia Bauzer Medeiros, and Daniela Santos Oliveira developed the project design and methodology. Rebecca Koskela conducted the comparative analysis of certification frameworks and analyzed the survey data, with support from Daniela Santos Oliveira, who set up, distributed, and collected the survey. Daniela Santos Oliveira managed the project, created data visualizations, and wrote the original draft, with contributions from Rebecca Koskela and Dale Peters. The manuscript was reviewed and edited by Claudia Bauzer Medeiros, Suzie Allard, David Castle, Meredith Goins, and Devika Madalli. Suzie Allard and David Castle secured project funding.
All authors reviewed and approved the final manuscript.