Koustav Chatterjee is an Indian chess player who was awarded the title of International Master (IM) by FIDE, the international chess federation. In 2020, Chatterjee won the Indian National Junior (U-19) Championship. He secured his first Grandmaster (GM) norm in August 2021 in Belgrade, Serbia at the 3rd First Saturday tournament. His second GM norm came in September 2021 at the Silver Lake Open in Serbia, and his third and final GM norm was achieved in October 2021 at the First Saturday GM Norm tournament in Budapest.
In his career, Chatterjee has earned several other significant titles, such as the Asian Junior Championship in 2019, the Delhi Grandmaster Open 2019 and the KIIT International Open 2019. In the KIIT International Open, he was unbeaten and finished second behind the Armenian grandmaster Karen Grigoryan.