Hall, the former South Africa allrounder, has been with the county since 2008 and captained them between 2010 and 2012 while Spriegel arrived at Wantage Road from Surrey in 2012.
Hall is Northamptonshire's leading Championship wicket-taker this season with 30 scalps at 39.23 while he has also scored 556 runs at 26.47. Spriegel has also been ever-present in the side, scoring 494 runs at 22.45 and taking eight wickets 47.25.
Heading into the final month of the season Northamptonshire face certain relegation, sitting 77 points adrift of Durham in eighth place having lost 10 of their 12 matches. The defence of their T20 title ended in the group stages and they also missed out on a quarter-final spot in the Royal London Cup.
Northamptonshire's chief executive, David Smith, said: "These are always difficult decisions to make regarding players futures, but they are always made in the best interests of moving the club forward over the next few years."
"The club wishes to place on record its sincere thanks to both players for their commitment throughout what has been a difficult summer for everyone connected with Northants Cricket.''