For the full 40 Under 40 list, click here.

As coding interns at Yahoo! in 2012, Asthana and Sobti faced a problem common among developers—testing APIs (application programming interfaces, which let software products ‘communicate’). Asthana worked on this as a side project, and the first iteration of Postman was a Chrome app. Its simple and user-friendly interface caught on like wildfire, and Asthana, along with Sobti and Kane, set up Postman in 2014. While well-regarded among developers, it was relatively unknown more broadly. That changed last year when it raised $150 million at a $2-billion valuation, making it India’s fourth SaaS unicorn.

Follow us on Facebook, Twitter, YouTube & Instagram to never miss an update from Fortune India. To buy a copy, visit Amazon.