About MarketSizer

We make messy market signals make sense.

You're surrounded by market signals but without the timing layer, they're just data without direction. We help SaaS teams turn that chaos into clarity, so they know exactly when to act, win, and grow.

1M

In Funding since 2023

We turn complex subscription data into precise, actionable GTM signals.

Our work isn't just about numbers or technology. It's about enabling real people to make a difference in their business by knowing who to focus on, when to act, and why it matters.

A shift that changed everything.

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.
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At the time, our focus was on top-down market sizing but as we were building we discovered something even more impactful. The challenge wasn't just sizing markets; it was uncovering actionable, competitive intelligence that teams could use to win, grow, and retain their ideal accounts.

So, we pivoted.

What began as a straightforward market calculator evolved into what might be the largest and most accurate bottom-up subscription data set ever built, powered by more than 20 million subscription signals.
We realised the real challenge wasn’t market sizing, it was knowing exactly when an account was ready to buy, renew, or expand. That’s why MarketSizer is built to give GTM teams the timing edge they’ve never had before.

What drives us forward.

We believe that every SaaS team deserves the clarity and confidence to scale smarter, faster, and more sustainably.

Too often business struggle with fragmented data and unclear priorities. At MarketSizer, our purpose is to bridge the gap by turning complex signals into actionable insights that help teams work smarter together, prioritise better, and grow confidently.