In what is both one of the bigger tech acquisitions and recruitment stories of the year, the Japanese firm Recruit Holdings is set to buy Glassdoor in a deal worth $1.2bn. The buyer, which also owns recruitment site Indeed.com, will gain access to a vast database of employee reviews, salary data and a huge volume of active job seekers. Glassdoor is also the second-largest job site in the US – the largest being Indeed – so the synergies are obvious, especially if the new owner opts to further integrate the two sites. Whether this justifies the gigantic valuation is another question entirely – the barrier to entry for new rivals doesn’t seem especially high to me, leaving the sector very open to further disruption. But Glassdoor, which has 30m members worldwide, is already growing faster than LinkedIn, Indeed and Monster, so what lessons can employers learn from it?