other Microsoft services, applications and Windows components. For years, it was a private API used by Microsoft only, but has since become a published API that anyone can use. Work began on Data Access Engine (DAE) in March 1989 when Allen Reiter joined Microsoft. Over the next year a team of four developers worked for Allen to largely complete the ISAM. Microsoft already had the BC7 ISAM (JET Red) but began the Data Access Engine (DAE) effort to build a more robust database engine as an entry in the then new client-server architecture realm. In the spring of 1990, BC7 ISAM and DAE teams were joined to become the Joint Engine Technology (JET) effort; responsible for producing two engines a v1 (JET Red) and a v2 (JET Blue) that would conform to the same API specification (JET API). DAE became JET Blue for the color of the flag of Israel. BC7 ISAM became JET Red for the color of the flag of Russia. While JET Blue and JET Red were written to the same API specification, they shared no ISAM code whatsoever. They did both support a common query processor, QJET, which later together with the BC7 ISAM became synonymous with JET Red. JET Blue first shipped in 1994 as an ISAM for WINS, DHCP, and the now defunct RPL services in Windows NT 3.5. It shipped again as the storage engine for Microsoft Exchange in 1996. Additional Windows services chose JET Blue as their storage technology and by 2000 every version of Windows began to ship with JET Blue. JET Blue was used by Active Directory and became part of a special set of Windows code called the Trusted Computing Base (TCB). The number of Microsoft applications using JET Blue continues to grow and the JET Blue API was published in 2005 to facilitate usage by an ever-increasing number of applications and services both within and beyond Windows. A Microsoft Exchange Web Blog entry stated that developers who have contributed to JET Blue include Cheen Liao, Stephen Hecht, Matthew Bellew, Ian Jose, Edward "Eddie" Gilbert, Kenneth Kin Lum, Balasubramanian Sriram, Jonathan Liem, Andrew Goodsell, Laurion Burchall, Andrei Marinescu, Adam Foxman, Ivan Trindev, Spencer Low and Brett Shirley. In January 2021 Microsoft open sourced ESE. It was posted to GitHub with the permissive MIT License. Comparison to JET Red While they share a common lineage, there are vast differences between