Answer by taking a quote from the following article:

Jan van Eyck (Dutch: ['jan van 'eik]) (before c. 1390 - 9 July 1441) was an Early Netherlandish painter active in Bruges. He is often considered one of the founders of Early Netherlandish painting, and, one of the most significant representatives of Northern Renaissance art.

Van Eyck served as official to John of Bavaria-Straubing, ruler of Holland, Hainault and Zeeland. By this time he had assembled a small workshop and was involved in redecorating the Binnenhof palace in The Hague. After John's death in 1425 he moved to Bruges and came to the attention of Philip the Good c. 1425. His emergence as a collectable painter generally follows his appointment to Philip's court, and from this point his activity in the court is comparatively well documented. He served as court artist and diplomat, and was a senior member of the Tournai painters' guild. On 18 October 1427, the Feast of St. Luke, he travelled to Tournai to attend a banquet in his honour, also attended by Robert Campin and Rogier van der Weyden.  A court salary freed him from commissioned work, and allowed a large degree of artistic freedom. Over the following decade van Eyck's reputation and technical ability grew, mostly from his innovative approaches towards the handling and manipulating of oil paint. Unlike most of his peers his reputation never diminished and he remained well regarded over the following centuries. His revolutionary approach to oil was such that a myth, perpetuated by Giorgio Vasari, arose that he had invented oil painting.  His brother Hubert van Eyck collaborated on Jan's most famous works, the Ghent Altarpiece, generally art historians believe it was begun c. 1420 by Hubert and completed by Jan in 1432. Another brother, Lambert, is mentioned in Burgundian court documents, and may have overseen his brother's workshop after Jan's death.

Where was he a court painter?
He served as court artist and diplomat, and was a senior member of the Tournai painters' guild.