Slack Fund and Citi Ventures have reinvested in the communications software developer through a round that lifted its overall funding to $175m.

Enterprise software producer Slack and financial services firm Citi have contributed to a $120m series C round for US-based communications software developer Nylas through subsidiaries Slack Fund and Citi Ventures respectively.

The round was led by hedge fund manager Tiger Global Management and also featured 8VC, Round13 Capital, Scale Asia Ventures, Owl Rock Capital, Blue Cloud Ventures and private investors Patrick Collison, John Collison, Sebastian Siemiatkowski and Tony Fadell.

Nylas has built an application programming interface platform that helps software…