sharedsource

Sharedsource, or shared source, is a term used to describe a licensing approach in which software source code is made available to a restricted external audience under terms designed to balance transparency with intellectual property protection. It is distinct from open source in that access and redistribution are typically limited to defined customers, partners, and developers, and the source is not released to the general public.

A notable early example is Microsoft's Shared Source Initiative (SSI), launched in the early 2000s to provide select customers and partners with access to portions of Windows, Internet Explorer, and related software source code. Access was granted under licenses that specified who could view the code, for what purposes, and under what confidentiality obligations. The program aimed to support security reviews, interoperability testing, and internal development by trusted entities.

Licensing and scope varied by product and program. In many cases, the license allowed viewing and evaluation, with restrictions on redistribution and production use; in some instances limited rights to modify the code were offered only under tightly controlled arrangements. Access often required a non-disclosure agreement and adherence to a defined process for requesting and revoking access.

Impact and legacy of shared source include providing a pathway for enterprises to audit and understand complex software without a full open-source release. Critics argued that it offered less transparency than open source and could create a confusing middle ground in licensing. Over time, such programs were scaled back or replaced by other transparency initiatives and more permissive licensing for some components.