With an average five-star rating across more than 7,000 reviews on the Google Chrome Web store, Postdot Technologies Inc. thinks it has a good thing going with Postman, a tool for building, testing and documenting application program interfaces. Now it has raised $7 million to see how much further it can go.

Introduced in 2012, the free Postman extension boasts more than 3 million installations and more than 1.5 million active monthly users at 30,000 companies. Its popularity reflects the rapid rise of APIs as a popular way for developers to expose services and data through secure and trackable portals. The Postman browser plug-in is free, but the company also operates a paid service – Postman Cloud – that provides team collaboration tools.

Series A funding is being spearheaded by Nexus Venture Partners, a venture capital firm that concentrates its investments in the US and India. The Bangalore-based Postdot previously raised capital in a convertible round. The funds will primarily be used for market development around the paid cloud service.

Co-founder Abhinav Asthana told SiliconANGLE that he developed the product four years ago as a GUI-based replacement for the command-line Curl data transfer tool he was using at the time. Initial growth was driven by word-of-mouth. “It’s become the de facto standard for sharing and testing APIs,” he said.

APIs, like any software, need to be tested prior to release. For example, developers check to make sure API calls return the right data and that multiple APIs don’t overlap each other and cause conflict.

The Postman cloud service provides for team collaboration tools and sharing of test cases, as well as tools for building documentation. “We see that companies don’t have visibility into their own API infrastructure,” Asthana said. “Our cloud lets them see that. Once they have full visibility, they can build apps more reliably.” Shared toolkits can also be useful in bringing new developers up to speed quickly.

Postman reference customers include Box Inc., Walgreen Co., Intuit Inc., IBM, VMware Inc. and Apigee Corp., which is being acquired by Google. Asthana said Postman is the API-development tool of choice for nine of the 10 largest cloud computing providers. An upcoming version of the cloud suite will add monitoring and testing in the cloud. The service is priced at $6 per user per month, or $60 per user per year.

Image via getpostman.com