The J9 was the Swedish designation for the American P-35A. The P-35 was chosen in 1935 in a competition for a single seat fighter for the USAAC, however, the USAAC later rejected the P-35 n favour of Curtis's design in 1937. Thus, Seversky and their P-35 went to Europe looking for possible buyers. Sweden set 3 orders, one for 15 units, another for 45, and a last one for 60. The first 60 aircraft arrived without issues, however the last 60 were diverted to the Pacific Theatre, where they suffered very heavy losses.

It was introduced during Update "Air Superiority" as a reward for the 2023 Winter Extreme event. The J9 features a very peculiar design, being similar to early Italian monoplane fighters. It has access to 4 MGs, of which 2 are hard-hitting 13.2 mm guns with HEF shells. The aircraft is a bit slow compared to others around its BR, but it compensates this with a very good turning radius and a decent climb rate. It should be used as a dogfighter, entering fights from above to have lots of energy when turning.