At the age of twelve, Frommann moved from his home club SV Oberachern to the youth academy of SC Freiburg.[3] In 2017, he made his debut in the Regionalliga Südwest for SC Freiburg II, the reserve team of Freiburg, with whom he had previously enjoyed promotion from the Oberliga Baden-Württemberg without making any appearances.[4] In the 2018–19 season, Frommann was part of the professional first team squad of SC Freiburg.[5]
Loan to Sonnenhof Großaspach
For the 2019–20 season, the goalkeeper was sent on loan to 3. Liga club SG Sonnenhof Großaspach.[6] On the matchday 8, Frommann was given preference over regular goalkeeper Maximilian Reule in a match against Bayern Munich II and made his debut in professional football.[7] The rest of the season, he was mostly a backup to Reule, as Sonnenhof Großaspach suffered relegation by finishing in the penultimate spot in the league table. Upon his return to Freiburg, he was not a part of the club's future plans, and in early October 2020 his contract was terminated shortly before the transfer window was closed. At the same time, he received the offer to continue training with Freiburg until he found a new club.[8]
SV Meppen
In November 2020, Frommann signed a contract with 3. Liga club SV Meppen, valid until the summer of 2022, after regular keepers Luca Plogmann and Matthis Harsman had suffered injuries.[9] In May 2022, it was announced that his expiring contract would not be extended, making him a free agent after the season.[10]
After football
In January 2023, Frommann announced his retirement from football on medical advice due to persistent and irreparable hip problems.[11][12]
Following his retirement, Frommann co-founded FUTURE GOAL alongside football coach and bank clerk Sven Oliver Gercke. The company aims to assist professional athletes in transitioning smoothly into life after their active careers.[13]
