License Readium SDK

Readium SDK modules are publicly licensed as Open Source Software via Gnu Affero General Public License Version 3. This license contains terms incompatible with use in closed-source software including a copyleft provision. 

Readium Foundation also makes available an Alternative License based on the Apache License which provides additional rights targeted to commercial adopters utilizing Readium SDK in closed-source software, including not having any copyleft provision.

Licensees (via the Alternative License) are required to make a minimum financial contribution to the Readium Foundation, and to pay for ongoing extended license coverage (which makes the Alternative License applicable to updates to the Readium SDK software). The rationale for this dual-license approach and associated fee structure is to help assure a requisite level of ongoing development, project management, and QE support for the software.

The base contribution required to qualify for the Alternative License for Readium SDK is $5,000 USD for not-for-profit organizations and $30,000 USD for commercial (for-profit) organizations. For commercial organizations, up to $25,000 of the $30,000 may be waived by prior agreement if the for-profit licensee contributes at least 3 person-months of mutually-agreed useful development to a Readium Foundation project. For non-to-profi organizations who choose to pay the discounted $5,000 rate, the source code redistribution option in the license is not available. 

Extended License Coverage ("maintenance") is currently $3,000 USD per year. First-year maintenance is required and is invoiced with the initial license fee. Subsequently it is billed annually on the anniversary of the initial invoice. Extended License Coverage may be declined after the first year (in which case the Alternative License rights are applicable only to versions of Readium SDK available on or before the expiration of the term of coverage). It may be reinstated at any time with payment of an additional years's maintenance fee. By way of example if a licensee declines extended license coverage on its due date but then wishes to reinstate it 6-months later or 2-years later, $6,000 would be invoiced to reinstate the maintenance for an additional 12 months from the invoice date.

Licensees of Readium SDK are strongly encouraged to become active contributors to the Readium SDK project and other projects within Readium Foundation. Prospecitve licensees should understand that their initial base contribution and ongoing maintenance fees are insufficient to fully fund the ongoing development and maintenance of Readium SDK software and that voluntary contributions are the primary "fuel" ensuring any open source project's viability. Contributions can include development, bug fixing, bug reporting, performance analysis, and other aspects of the overall development process.

Licensees of Readium SDK are also strongly encouraged, but not required, to become members of Readium Foundation. Members of Readium Foundation govern the Foundation, including electing the Board of Directors and approving matters put to votes of the membership. Membership dues provide financial support for the overhead of running the open source consortium. More information about joining Readium Foundation is available here.

If you are interested in licensing Readium SDK software please email

The process is straightforward: on request we will invoice (via email) your organization for the applicable fee and first-year extended license coverage. At any time after receipt of payment you may request execution of the license agreement, after which the "clock" for your prepaid first-year extended license coverage will begin.