[1] On January 20, 2018, Appleby made his NHL debut in a 3–1 loss to the Philadelphia Flyers, saving 24 shots when he replaced Keith Kinkaid.

[4] Despite making his NHL debut the final season of his entry-level deal, Appleby as an impending restricted free agent was not tendered a qualifying offer by the New Jersey Devils on June 25, 2018.

[8] On July 9, 2019, Appleby agreed to continue in the AHL, signing a one-year contract with the Milwaukee Admirals, affiliate to the Nashville Predators.

[10] Approaching the final stages of the regular season, Appleby was signed by parent affiliate, the New York Islanders, to a two-year, two-way contract on April 9, 2021.

[11] As a free agent from the Islanders organization, Appleby was signed to a one-year AHL contract with the Charlotte Checkers, affiliate to the Florida Panthers, on July 2, 2024.