Postman, an API (application programming interface) development firm based in San Francisco, has secured $225 million in a Series D financing, valuing the company at $5.6 billion. Insight Partners, a global private equity and venture capital firm based in New York, led the round, which included new investors Coatue, Battery Ventures, and Bond Capital, as well as current investors CRV and Nexus Ventures partners.

Individual investors include Gokul Rajaram, the CEO of DoorDash, and Girish Mathrubootham, the founder of Freshworks. In total, the company has raised over $430 million in four waves.

Postman has now surpassed BrowserStack as the most valuable SaaS (Software as a Service) startup from India, with a valuation of $4 billion following a $200 million fundraising round headed by Bond Capital in June.

Postman's worth has increased by 180 percent since it obtained $150 million from Insight Partners and others a year ago, when it was valued at $2 billion.

Postman intends to use the funds to grow its sales, marketing, product, and technical teams. In addition, to build a healthy and thriving API ecosystem, the firm will continue to invest in its global developer community, help students through creative API literacy programmes, and contribute to open-source projects.

Postman CEO and Co-founder Abhinav Asthana said: "this new round of funding will help Postman dramatically increase the speed of that forward motion. We’re committed to helping developers who are building the future with APIs.”

Postman now has over 17 million users and 5,00,000 businesses on its platform, including Salesforce, Stripe, Kroger, Microsoft, Cisco, and PayPal, making it the world's largest API community. Abhinav Asthana, Ankit Sobti, and Abhijit Kane launched the company in 2014.

Postman joined the unicorn club last year after raising $150 million in a series C fundraising round with a worth of roughly $2 billion.

“APIs have quickly become the fundamental building blocks of software used by developers in every industry, in every country across the globe—and Postman has firmly established itself as the preferred platform for developers,” said Insight Partners Managing Director Jeff Horing.

Since the beginning of 2020, Postman has employed more than 300 people across 13 countries, more than tripling its workforce and adding thousands of new customers to a customer base that includes 98 percent of the Fortune 500.