Exeter's Millenic Alli scored a goal from the rebound after his penalty was saved, securing a 1-1 draw against Peterborough in the Sky Bet League One and extending the home team's winless streak.
Peterborough seemed on course for their first league victory in seven games when Hector Kyprianou opened the scoring, but Alli's last-minute goal denied them the win.
In the 30th minute, Peterborough nearly took the lead as Ryan de Havilland's shot hit the post after a pass from Ricky-Jade Jones.
The breakthrough for Peterborough came in the 34th minute through a well-executed play involving De Havilland and Malik Mothersille setting up captain Kyprianou for a precise finish past Joe Whitworth.
Peterborough had a chance to double their lead in the 79th minute, but Whitworth saved a shot from Mothersille and Purrington cleared Lindgren's rebound off the line.
Exeter's luck changed when they were awarded a late penalty after Tayo Edun fouled Demetri Mitchell. Alli's penalty was saved by Nicholas Bilokapic, but he followed up to score on the rebound.