Karin Tsai, director of engineering at Duolingo, will be speaking at TechCrunch City Spotlight: Pittsburgh on June 29

TechCrunch City Spotlight: Pittsburgh is getting closer, with impressive featured speakers including Carnegie Mellon University President Farnam Jahanian and Mayor Bill Peduto. However, we’ve saved the best for last: Our last speaker is Karin Tsai, director of engineering at Duolingo, a $2.4 billion business that is all about making language learning fun and accessible.

The event will be held on June 29, so make sure to register here (for free) to listen to these conversations, enjoy the pitch-off and network with local talent.

Tsai joined Duolingo in 2012 as one of its first engineers, and witnessed firsthand the growth of the company from a scrappy startup into a 400-person global business. Her timestamp on the company has made her a key decision-maker in many of its biggest decisions, from which features to scrap to how to monetize without compromising its mission of providing free education to all.

One thing to note is that even though a whimsical owl and creative UX might seem straightforward, the language learning universe is controversial and requires healthy debate — and testing — for anyone within it.

“We’re trying to do things that no other apps really tackle: How do we create an experience that actually makes you extremely proficient in a language while accommodating the expectations from our learners” to be fun and convenient, Tsai told me when I interviewed her for my Duolingo EC-1. “Balancing efficacy with engagement is something that we constantly struggle with.”

In this chat, Tsai will break down how Duolingo turned to A/B testing to answer some of its biggest questions. We’ll also chat about more meta topics, as when to give up on measuring the unmeasurable, and when tests fail and instinct reigns supreme. Tsai admitted to me once that Duolingo spent years trying to figure out how to find a metric that could encompass learning comprehension and engagement in one fell swoop.

“What used to freeze us is that we thought we would need such a metric to make progress,” she explained. “And I think what honestly liberated us was saying essentially, ‘Screw it.’ We couldn’t make progress waiting for a learning metric.”

I’ll be interviewing Tsai, so anyone who registers for this event is welcome to throw me questions for her that I’ll try to incorporate into my chat.

Tsai will give us the startup builder perspective, while Mayor Peduto will speak to the challenges of building a startup ecosystem, and Carnegie Mellon University President Farnam Jahanian will discuss how to go from student to startup with the correct resources.

Don’t forget to register for this free event on June 29th (click here to register) so you can watch these chats and riff with audience members during networking opportunities. If you’re an early-stage startup founder based in Pittsburgh, you should apply to pitch your startup (click here to apply). Expect to do a live two-minute pitch, get feedback from local VCs, and maybe even win our pitch-off.

I can’t wait to see you there!