The General Electric XA100 is an American adaptive cycle engine demonstrator being developed by General Electric (GE) for the Lockheed Martin F-35 Lightning II and forms the technological foundation for the company's XA102 propulsion system for the United States Air Force's sixth generation fighter program, the Next Generation Air Dominance (NGAD).

The 45,000 lbf (200 kN) thrust class engine is expected to be significantly more powerful and efficient than existing low-bypass turbofans.

[5] Further contract awards and modifications from Air Force Life Cycle Management Center (AFLCMC) in 2018 increased the focus on re-engining of the F-35, and GE's design became "F-35 design-centric"; there has also been investigations on applying the technology in upgrades for F-15, F-16, and F-22 propulsion systems.

The XA100 can adjust the bypass ratio and fan pressure ratio to increase fuel efficiency or thrust, depending on the scenario, by employing an adaptive fan that can direct air into a third bypass stream in order to increase fuel economy and act as a heat sink for cooling; in particular, this would enable greater use of the high speed, low altitude part of the F-35 envelope.

In addition to three-stream adaptive cycle configuration, the engine also uses new heat-resistant materials such as ceramic matrix composites (CMC) to enable higher turbine temperatures and improved performance.