The Cobblers boss snapped up goalkeeper Ryan Clarke from his former club Oxford United on Thursday to compete with recent signing Adam Smith,
Wilder also wants another centre half, a midfielder and a forward player.
With pre-season friendlies starting at Sileby this weekend, the Town manager may use the opportunity to look at free agents who are bidding to win a contract at Sixfields.
A look back at the Cobblers Mad archives for last summer shows that three trialists appeared in the friendly at Eastleigh with Lawson D'Ath going on to earn a permanent deal.
Update: Four trialists were included in the squad that faced Sileby Rangers on Sunday in Town's first outing of the summer. Rod McDonald, Gozie Ugwu, Sam Hoskins and Joel Purkiss were the men looking to impress with former Southampton academy man Hoskins netting in the first-half.
Hoskins and Ugwu were recently released by Yeovil Town.