Rokt uses AI to present offers from other brands after customers make an online purchase. Founded in 2012 and profitable since its first year, it's one of the most successful venture capital-backed Australian start-ups after Canva. Led by former Jetstar Airways boss Bruce Buchanan, it grew revenue by 43% to $US600 million last year and has struck a new funding round valuing it at $US3.5 billion (Au$5.6 billion).