Tamás Kádár is co-founder and chief executive of SEON, the fraud prevention and anti-money laundering company that scores sign-ups, logins, and payments for thousands of online businesses. He started it in Budapest in 2017 with his university friend Bence Jendruszák.
A Crypto Exchange Under Attack
Kádár and Jendruszák met as students in Budapest, and their first joint project was a cryptocurrency exchange for Central and Eastern Europe. It drew fraudsters almost at once. In one interview he described the chargebacks, identity theft, and multi-accounting they faced, attacks that came close to sinking the business.
The anti-fraud tools on the market at the time were slow, opaque, and built for large banks, and they made life harder for honest users. The two founders decided to build their own: a system that looked at the digital footprint behind an email address or phone number and could block fraud without blocking growth.
Building SEON
They founded SEON in January 2017. A London office followed in 2020, then a new Budapest base, an office in Austin in 2021, Jakarta later that year, and Singapore in 2025. Creandum led a Series A in 2021 and IVP led a $94 million Series B in 2022. In 2023 both founders made the Forbes 30 Under 30 Europe list.
In September 2025 Sixth Street Growth led an $80 million Series C that took total funding to $187 million. Kádár framed the round around one idea: companies should be able to stop fraud without impeding legitimate growth.
From Fraud Scores to a Full Platform
Under his leadership SEON added AML screening and transaction monitoring, launched identity verification in January 2026, and opened its data to outside AI tools in June 2026. It now protects more than 5,000 businesses and competes with Sardine, Feedzai, and Oscilar. He also writes about fraud for the Forbes Technology Council and HackerNoon.
The company still carries the mark of that first exchange. Every product decision returns to the question two students asked when their own business was under attack: how do you keep the fraudsters out and let everyone else in?
