Over the past months, many of you have experienced periods of slowness and occasional service interruptions on Zenodo. We would like to explain the current situation and outline the steps we are taking to address it.

Increased traffic and automated access

Zenodo traffic has increased significantly, not only from human users but also from automated systems, including bots, harvesters for AI and people using AI. These systems generate a sustained and aggressive load on the platform. Many of these automated systems do not respect our rate limits and actively try to circumvent them, creating additional strain. On average, we now observe around 180 requests per second. At peak times during working hours, this can easily reach 250 requests per second and more. The current Zenodo infrastructure was designed based on the traffic patterns observed during the migration to the next-generation platform, InvenioRDM, in 2023, when the load was lower and more predictable.

This affects both browsing and file transfers, resulting in slower uploads and downloads, as well as occasional unavailability. Basic mitigation techniques such as blocking and rate limiting are no longer sufficient on their own. More advanced traffic management and protection mechanisms are required, together with infrastructure upgrades.

Planned improvements

In the coming weeks, we will progressively upgrade the platform and deploy additional mitigation measures to better handle the increased load and reduce the impact of abusive or malicious traffic. These changes will be rolled out step by step in order to preserve service continuity.

During this period, we kindly ask for your patience. At the moment, support requests related to performance issues or temporary slowness are difficult to address individually, as the root causes are already identified and are being handled at the infrastructure level.

As Zenodo grows, our support team is receiving more support requests than ever. While we work through these requests, the fastest way to find a solution is often through our Help Portal and FAQs. We've designed these resources to give you instant answers to common questions so you can get back to your research without the wait.

We will keep you informed of major developments and improvements as they are deployed.

As always, Zenodo remains committed to its core mission of supporting open science, reserving research outputs, and providing reliable access to research for the global community. Ensuring that research remains open, accessible, and reusable continues to guide our technical and operational decisions.

Thank you for your understanding and for your continued use of Zenodo.

As Zenodo continues to grow, we're taking steps to keep the service fast and reliable for everyone. Over the past year, we've seen a sharp rise in aggressive and covert harvesting activity targeting our search endpoints, and often at volumes that disrupt normal use. Our team has been blocking misbehaving clients on an almost daily basis to maintain stability for researchers who rely on Zenodo for browsing, searching, and depositing their work. As these attacks have intensified, we're introducing new rate limits on our records search API to help protect the platform and ensure fair access for all users.

What's changing?

Starting today, we're enforcing the following limits on our records search endpoints:

• Page sizes: Maximum 25 results per page for anonymous requests, 100 results per page for authenticated requests
• Request frequency: Maximum 30 requests per minute (for both anonymous and authenticated users)

These limits ensure that Zenodo remains responsive for everyone. The higher page limit for authenticated requests also allows us to contact users if we notice usage patterns that our other APIs could better serve.

Why these changes?

Our infrastructure prioritizes researchers who are searching, browsing, and discovering content on Zenodo. But we've seen automated systems request very large amounts of data very quickly (up to 500 requests per second), which uses up resources and slows things down for everyone else.

After analysing current access patterns, we designed these new limits to accommodate typical use cases. If you're just searching for related work, browsing records, or managing your community, you won't notice a difference.

Better alternatives for bulk data access

If you've built scripts, applications, or integrations using the search API for bulk harvesting, or need large amounts of Zenodo metadata (to build indexes, perform analysis, or keep external systems synchronized), we highly recommend using the following methods:

• OAI-PMH: A standardized protocol for harvesting metadata and keeping systems synchronized with repositories like Zenodo. It supports incremental updates (only fetching what's new or changed), filtering by community, and multiple metadata formats. OAI-PMH delivers 50 records per page and has the same 30 requests per minute limit.
• Metadata dumps: Monthly exports of all Zenodo metadata that you can download and process on your own systems. This is the most efficient way to access bulk metadata, especially if you need to analyze large portions of Zenodo's content. The dumps are available in DataCite XML and JSON formats.

Looking ahead

We're working to scale Zenodo sustainably while keeping the service responsive and user-friendly. We'll closely monitor how these changes perform and make adjustments if needed. As the threat landscape is evolving rapidly, we are very likely to introduce further mitigation measures in the future.

If you have questions regarding these changes, or need help transitioning to OAI-PMH or metadata dumps, please contact our support team.

In March 2024, the EU and CERN officially launched the EU Open Research Repository on Zenodo in a pilot phase, and since then, it has rapidly gained momentum. Over the past several months, we have successfully onboarded 130 EU-funded projects as EU projects communities - a feature that provides projects an easy go-to solution for sharing and preserving the research outputs from their projects. About 23% of all EU-funded projects (FP7, Horizon 2020 and Horizon Europe) during the past 10 years have a research output on Zenodo amounting to 11.000 different grants.

As we now move from the pilot to the production phase, the EU Open Research Repository is set to become an essential tool for EU projects, offering an easy, accessible platform to support the broader implementation of EU open science policies.

Supporting EU Open Science policy

The EU has long been a driving force behind open science, progressively supporting its adoption through successive Research and Innovation Framework Programmes. This effort began with the Open Access pilot in FP7, followed by the addition of Open Data provisions in Horizon 2020, and now, in Horizon Europe, through a strong commitment to comprehensive open science practices. These practices include open access to scientific publications, responsible management of research data, and a clear focus on FAIR (Findable, Accessible, Interoperable, Reusable) principles.

The establishment of the EU Open Research Repository represents a continuation of these efforts. Built upon the foundation of Zenodo — a general-purpose open repository operated by CERN — the new repository enables researchers to deposit a wide range of outputs, including papers, datasets, software, posters, presentations, and more. This platform provides an easy, go-to solution for EU programme beneficiaries to comply with open science requirements, helping them make their research outputs FAIR in practice.

Managed by CERN on behalf of the European Commission, the EU Open Research Repository helps EU-funded projects streamline the management and dissemination of their research outputs, supporting the continued growth of the open science ecosystem in Europe.

New Features During the Pilot

Today, we are also excited to announce the launch of our new browse feature, which offers users an overview of the content within the EU Open Research Repository. This feature allows users to browse research outputs by funding programme, subject, or project, providing an intuitive, user-friendly experience. All of this is made possible thanks to the integration of high-quality open data from CORDIS, the EU’s project database, which provides funding programme details and subject classifications using EuroSciVoc.

The pilot phase introduced several new features designed to make it easier for EU-funded projects to manage their research outputs. One of the key additions was a workflow for projects to request a project community, which allows them to either create a new community or integrate an existing Zenodo community into the EU Open Research Repository.

What's next?

As we transition into the production phase, we have several key objectives. First and foremost, we will continue to integrate feedback from the early adopters who participated in the pilot phase. Their insights have been invaluable in shaping the platform, and we are committed to ensuring that their needs and suggestions are addressed as we move forward.

In addition to this, we plan to onboard approximately 2,700 project communities that we have already identified on Zenodo. These projects will benefit from the new features and improved workflows that have been developed during the pilot.

Another important focus for the future is the automatic integration of EU-funded submissions made to Zenodo that fall outside of dedicated project communities. This will further streamline the process of depositing research outputs and ensure that all relevant submissions are included in the EU Open Research Repository.

Lastly, we are committed to enhancing the FAIRness of Zenodo by implementing improvements that will better support domain-specific features. This will also involve harmonizing curation efforts across different projects to ensure the high quality of metadata associated with deposited research outputs.

Funding

The EU Open Research Repository is funded by the European Union under grant agreement no. 101122956 (HORIZON-ZEN).

You can learn more about the HORIZON-ZEN project on https://about.zenodo.org/projects/horizon-zen/