the long-term survival of scholarly content

CLOCKSS is a collaboration of world leading academic publishers and research libraries, providing a sustainable digital archive to ensure the long-term survival of scholarly content.

Using the award-winning LOCKSS opensource software, which was invented specifically for the long-term digital preservation of scholarly content, CLOCKSS is the only archive that assigns Creative Commons Open Access licenses to all triggered publications to ensure they are always open and available to everyone.

CLOCKSS is the only Trusted Digital Repository to receive the highest score for technology from the TRAC audit conducted by the Center for Research Libraries.



CLOCKSS (Controlled LOCKSS) employs a unique approach to archiving (Lots of Copies Keep Stuff Safe) that was initiated by Stanford University librarians in 1999. Digital content is stored in the CLOCKSS archive with no user access unless a “trigger” event occurs. The LOCKSS technology regularly checks the validity of the stored data and preserves it for the long term.

CLOCKSS operates 12 archive nodes at leading global academic institutions, preserving the authoritative versions of scholarship authored and published around the world.

This secure, robust, and decentralized infrastructure can withstand threats from technological, economic, environmental, and political failures. A destructive event in one location won’t jeopardize the survival of preserved digital content because the 11 other locations serve actively monitor and repair the disrupted location’s archive.

Another CLOCKSS advantage is that publications are preserved in their original format. When an unavailable publication is triggered, the authoritative version is migrated to an accessible, usable format tailored for up-to-date technology.

CLOCKSS has been designated as a trustworthy repository by the Center for Research Libraries’ Certification Advisory Panel. CLOCKSS received the only perfect score for Technology.

Click here to find out more about how CLOCKSS works and our technical overview.

Of the community, for the community

CLOCKSS is governed by and for its stakeholders. Our operations are governed by a Board of Directors with an equal number of librarians and publishers making decisions together about policies, procedures, priorities, and when to trigger content.

As the only digital archive that assigns a Creative Commons license to all triggered digital content, CLOCKSS benefits the greater global scholarly community by enabling permanent Open Access to abandoned and orphaned publications. As a result, recovered content becomes perpetually available to anyone with Internet access.

CLOCKSS is a very secure preservation service and is the best single choice for preserving the scholarly record. We also collaborate with other archiving solutions to ensure added redundancy and resilience and to ensure libraries and publishers have a choice of archiving solutions. Best practice is to ensure digital content is preserved in three distinct preservation services.


CLOCKSS participants have the opportunity to be deeply involved and help to keep the research community’s best interests at the forefront. CLOCKSS actively participates in the development of industry policies, practices, and standards.

Financially secure and sustainable

As an independent, tax-exempt 501(c)(3) not-for-profit charitable organization, CLOCKSS is committed to keeping its fees affordable so that libraries and publishers of all sizes and budgets and in all places can participate in CLOCKSS. Low operating costs make it possible to keep this commitment.

As a long-term preservation organization, CLOCKSS believes that a robust Succession Plan is required. In the unlikely event of the demise of CLOCKSS, four of our twelve library nodes have committed to continuing the preservation of the content in the archive.

Download a CLOCKSS overview in the following languages:

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