The 22-year-old is now a free agent after his contract with the Dons expired, despite their best attempts to negotiate a new deal.
However, because he’s aged under 24, Wimbledon would still be entitled to a fee.
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The Seasiders were linked with the central midfielder earlier this summer along with Championship newcomers Rotherham United and Ian Evatt’s Bolton Wanderers.
“I’d like to thank everyone at AFC Wimbledon for the last eight years,” Hartigan wrote on Twitter.
“It’s been a great experience to be part of the journey the club has been on and I wish all the staff, players and the fans the best for the future.”
Hartigan is a product of Wimbledon’s youth academy and he has long impressed in the middle of the park for the Dons.
He’s made 152 appearances for the club in total, scoring five times and claiming a further 13 assists.
It’s no secret the Seasiders are keen to strengthen in central midfield, having missed out on other targets - namely Cameron Brannagan and Oliver Norburn - on previous occasions.
Peterborough United claimed Norburn had agreed to join Blackpool this summer before suffering a serious injury.
While Pool do have numbers in that position, Kevin Stewart is unfortunately injury-prone and Matty Virtue and Sonny Carey are still working their way back from long-term injuries.
Grant Ward is no longer training with the club although Michael Appleton hasn’t ruled out taking another look at him later in pre-season.
Ward, who is still continuing his rehab from a long-term injury, was released at the end of last season alongside Ethan Robson, another midfielder.
Elsewhere, Kenny Dougall is still on the books while Callum Connolly and Reece James are two versatile defensive-minded players who can also fill in as and when required
Prior to Neil Critchley’s departure, the club had hoped to entice Ebou Adams from Forest Green Rovers but he opted to join Cardiff City instead.
The Seasiders have also been linked with Hartigan’s former Wimbledon teammate Jack Rudoni, who is attracting plenty of interest.