
How it all began.
MarketSizer started out as TamCalc, a tool built by Niall O'Gorman in Dublin with one clear purpose: to help businesses calculate market opportunities.
At the time our focus was on top-down market sizing, but as we kept building we discovered something even more impactful. The challenge was not just sizing markets - it was uncovering actionable, competitive intelligence that teams could use to win, grow, and retain their ideal accounts.








