Midfielder Tyler Frost joins the Reds on a two-year deal after his release from Reading.
Defender Tony Craig also joins for two years from League One Bristol Rovers.
Crawley has also signed Archie Davies after his release from Premier League Brighton and Hove Albion. The full-back joins on a two-year deal with an option of a third.
The Club has extended the contract of veteran Dannie Bullman. The central midfielder signs a one-year extension as a player/coach, joining John Yems and Lee Bradbury on the touchline. Dannie has played over 400 games for the Red Devils over a 14-year spell.
Crawley Town return to League 2 action from September.
The EFL has confirmed that the 2020/21 season will get underway across League 1 and League 2 on the weekend of 12th September. The season will end on 8th and 9th May next year with the play off finals reverting back to the Spring Bank Holiday weekend at the end of May.
The full fixture lists for next season are still being finalised.