Design of the Extra 300 was based on the Extra 230, an early 1980s monoplane having a wing made of wood. The Extra 300 has a weldedsteel tube fuselage covered in aluminium and fabric. The mid-set wing has a carbon fiber composite spar and carbon composite skins. A symmetrical airfoil, mounted with a zero angle of incidence, provides equal performance in both upright and inverted flight. The landing gear is fixed taildragger style with composite main legs and fiberglass wheel pants. The powerplant is a fuel-injectedLycoming AEIO-540 which produces 300 horsepower (224 kW).
The first two-seat Extra 300 made its maiden flight on 6 May 1988, with German type certification following on 16 May 1990. The single-seat Extra 300S flew on 4 March 1992.
The Extra 300 is stressed for ±10 G with one person on board and ±8 G with two. Some Extra 300s are certificated in the Experimental Category in the U.S., while others are certificated in the Aerobatic category.
An Extra 300L flying near Perth, Western Australia
An Extra 300S belonging to Patty Wagstaff. This image shows well the zero-incidence and zero-dihedral wing, used rarely but necessary in an aerobatic aircraft
The wing of the Extra 300L is set lower on the fuselage.
The 300S is a single-seat version, with a wingspan reduced by 50 cm (19½ in), and fitted with larger ailerons. 
The Extra 330SX was a custom development of the 300S with a wider-chord rudder, a larger elevator, and a more powerful Lycoming AEIO-580 powerplant producing 330 hp (246 kW). Some 300Ss were sold with the "bigger tail" of the 330SX. The 330SX was later replaced by the 330SC.
The 300SP is a performance version of the 300S single-seater. Weight was reduced, and the tail of the 330SX installed. It is discontinued, being replaced by the 330SC.
The 300SHP (HP=High performance) is an uncertified version of the 300SP with a Lycoming AEIO-580 engine.
The Extra 300L is a Lycoming AEIO-540 powered two-seat aircraft, with low mounted wing and shorter fuselage. More Extra 300L ("L" is a 2 seater version) aircraft have been produced than any other model. Its wing is mounted at the bottom of the fuselage, with its span reduced from 26 ft 3 in (8.00 m) to 24 ft 3 in (7.39 m). Improved ailerons boost the 300L's roll rate to 400 degrees per second. All 300Ls are fully certified under FAA and European Joint Aviation Authorities regulations.
The 300LP ("P" for performance) is a reduced weight version of the 300L, redesigned for better performance in competitions and airshows.
The Extra 330SC is a Lycoming AEIO-580-powered single-seat aircraft with improved roll rate and easier roll stops, designed specifically for Unlimited category competition. It is actually the only single-seater aerobatic aircraft built by Extra.
The Extra 330LX is a Lycoming AEIO-580-powered two-seat aircraft.
The Extra 330LT is a Lycoming AEIO-580 powered two-seat aircraft, adapted for touring. It has an EFIS cockpit and a reduced roll rate in comparison with the 330LX.