Scale AI, the four-year-old data labeling startup, has discovered that selling the picks and shovels needed to develop and apply artificial intelligence is big business.

The company, which created a visual data labeling platform that uses software and people to label image, text, voice and video data for companies building machine learning algorithms, has raised another $155 million. The funding round, led by Tiger Global, pushes Scale’s post-money valuation to more than $3.5 billion.

Importantly, Scale is now a “break even” business and is set up to continue to add employees and expand into new markets in a sustainable way, Scale’s CEO and co-founder Alexandr Wang told TechCrunch. Scale will use the funds to grow its workforce from 200 people to about 350 by the end of next year. (Those employee numbers don’t include the tens of thousands of contractors it uses to label data.) It’s also focused on new markets and adding products and platform capabilities.