FDX

FDX may refer to:
 * FedEx Corporation, original FDX Corporation, American logistics services company
 * FedEx Express, the ICAO code FDX, American cargo airline

Computing:
 * FDX, an expansion pack for the 1980s Memotech MTX computer
 * .fdx, the filename extension for Final Draft files
 * Fetch-decode-execute cycle, or FDX, basic operation cycle of a computer
 * Fast Data eXchange, a proprietary communication protocol used on boats

Telecommunications:
 * Full-duplex, communication circuit