Northampton had the better of the first-half chances, with Peter Gilbert firing a 25-yarder just wide in the 37th minute, and two minutes later top scorer Adebayo Akinfenwa headed over from a Luke Guttridge cross.
Chesterfield's best chance of the half came on the stroke of half-time when the much-travelled Barry Conlon headed over from an Ian Morris free-kick.
Northampton looked the more likely to score in the second half, and substitute Courtney Herbert failed to capitalise on some hesitancy in the Chesterfield defence on the hour mark.
Fellow substitute Stephen O'Flynn also had an opportunity to win it for the Cobblers in the 76th minute, while Herbert had a second chance late on but shot over from a good position.
Source: Team Talk