Ivar Hjalmar Jacobson (Swedish pronunciation: [ˈǐːvar ˈjɑ̂ːkɔbˌsɔn] ⓘ; born September 2, 1939) is a Swedish computer scientist and software engineer, known as a major contributor to UML, Objectory, Rational Unified Process (RUP), aspect-oriented software development, and Essence.

[citation needed] After his master's degree, Jacobson joined Ericsson and worked in R&D on computerized switching systems AKE[1] and AXE including PLEX.

In October, 1995, Ericsson divested Objectory to Rational Software,[2] and Jacobson started working with Grady Booch and James Rumbaugh.

He formed Ivar Jacobson International (IJI) in mid-2004,[3] which operates with offices in the UK and Sweden.

In 2000, with Agneta Jacobson, he founded Jaczone AB which developed a tool, Waypointer, to support RUP using intelligent agent techniques.

Dr. Ivar Jacobson's contributions span over 50 years, starting from components and architecture in 1967 and still ongoing today with Essence, which is described as "a common ground for engineering".

[citation needed] Standing on the experience of EssUP Ivar and his team, in particular Ian Spence and Pan Wei Ng, developed EssWork starting in 2006.

In November 2009, Jacobson, Bertrand Meyer, and Richard Soley ("the Troika") started an initiative called SEMAT (Software Engineering Method and Theory) to seek to develop a rigorous, theoretically basis for software engineering practice, and to promote its wide adoption by industry and academia.