The Low-Frequency Array, or LOFAR, is a large radio telescope network located mainly in the Netherlands, completed in 2012 by ASTRON, the Netherlands Institute for Radio Astronomy and its international partners, and operated by ASTRON's radio observatory, of the Netherlands Organisation for Scientific Research.

LOFAR consists of a vast array of omnidirectional antennas using a new concept in which the signals from the separate antennas are not combined in real time as they are in most array antennas. The electronic signals from the antennas are digitized, transported to a central digital processor, and combined in software to emulate a conventional antenna. The project is based on an interferometric array of radio telescopes using about 20,000 small antennas concentrated in 52 stations at present. 38 of these stations are distributed across the Netherlands and were funded by ASTRON. The six stations in Germany, three in Poland, and one each in France, Great Britain, Ireland, Latvia, and Sweden, were funded by these countries. Italy officially joined the International LOFAR Telescope (ILT) in 2018, and a station near Bologna was to become operational shortly after 2020. Further stations may also be built in other European countries. The total effective collecting area is approximately 300,000 square meters, depending on frequency and antenna configuration. Until 2014, data processing was performed by a Blue Gene/P supercomputer situated in the Netherlands at the University of Groningen. Since 2014 LOFAR uses a GPU-based correlator and beamformer, COBALT, for that task. LOFAR is also a technology precursor for the Square Kilometre Array.