Hartock began his football career with Martinique club US Robert. He moved to French giants Olympique Lyonnais in 2004, still only 17 years old. He played mainly for Lyon's B team in the CFA, and was the first team's third keeper for a number of years. He was released in 2011, having never made an official first team appearance for Lyon in his seven-year spell at the club.
On 11 August 2011, he signed a one-year contract with Stade Brestois 29.[5] He made his début for Brest in a Coupe de France match against Niort on 7 January 2012,[6] his first competitive first-team appearance for any side in French football. At the end of the 2011–12 season, Hartock signed a two-year contract extension with Brest. He made a further three Coupe de France appearances in the 2012–13 season, along with his début Ligue 1 match, a 2–1 defeat to Lille on 31 March 2013.
Hartock was the first-choice keeper for Brest in the 2015–16 and 2016–17 Ligue 2 seasons, playing in 36 games in each season. However he was replaced by manager Jean-Marc Furlan in May 2017 after two poor home performances. At the end of the 2016–17 season he was released from the final year of his contract.[7]
Quevilly-Rouen
Immediately after leaving Brest, Hartock signed with newly-promoted Ligue 2 side US Quevilly-Rouen.[8] He made 32 appearances, but the club were relegated at the end of the first season, and Hartock left due to budget constraints.[9][10]