Joe Takeuchi | API Sales Engineer, VerticalResponse
June 11, 2015

API KPI’s – 4 Keys to Tracking a Successful Developer Program


Once you’ve launched your developer program, and your API is ready for the spotlight, it’s important to have a strategy around how the success of your program will be measured. At VerticalResponse we pay attention to some key performance indicators (KPI’s) to gain insight into whether or not program is moving in the right direction. How your organization views success or failure will vary based on your business model. Below are four recommendations based on how we measure our program.

Developers/Apps Registered

Through VR’s Developer Portal, Mashery allows us to track each developer who registers to access . We also have visibility into each application a developer registers. This reporting is valuable for a number of reasons. From a pure volume perspective, it’s important to track the number of registered developers accessing your API, as well as the number of registered applications being built.  Where possible, we do our best to reach out to each developer and learn more about the application they’re building. Although information on these projects isn’t necessarily a KPI, connecting with developers consuming your API to find out about their experience working with your platform is incredibly valuable. Developers have helped us fine-tune our documentation and provided insight into how we should prioritize new API functionality. Without developer registration and tracking through our Mashery-hosted API portal getting our hands in this information would be difficult.

API Call Volume

Measuring pure API call volume via our portal’s analytics is another way to measure growth of our API program. We’re able to track total calls to , as well as blocked calls, timeouts, invalid keys, etc. Tracking increases in successful calls on a weekly basis tells us that developers are building applications and actually using them. Depending on your business model these calls may not always generate revenue, but growth in API call volume over time is an indicator that developers are successfully consuming your API and implementing it into their workflow.

Integration Usage

As more developers access our API, and we’ve built and launched API-based integrations and strategic partnerships, we’ve paid close attention to customer usage of these applications. We’ve been able to track usage by identifying the specific API token associated with each application via our portal’s API analytics, and we then track each time that API key is accessed. This provides us with insight into which integrations our customers are accessing most, and visibility into which functionality is resonating most with those customers. It’s been important too to the recent launch of VerticalResponse’s Integrations Marketplace, helping VR determine the marketplace’s impact on acquiring and retaining customers.

API-Generated Revenue

Although revenue may not be the ultimate goal of your API program, it’s still important to track the program’s impact on the bottom line. API users may access to build email lists, manage contacts, draft emails, etc. but our cash register only rings when our customers send email. Using Mashery’s reporting, we’re able to tie API users’ access tokens back to sent email activity. Tying each API users send back to the revenue generated from that said event gives us an idea of API-generated revenue. Seeing this revenue grow over time is evidence that users’ lists are growing and/or these users are launching email campaigns more frequently over time. You’ll be hard-pressed to find someone who’ll argue that API-generated revenue growth is not a sign that your program is succeeding. This is not to say that non revenue-generating API activity is not a sign of success. We also pay close attention to whether our API users are creating new contacts and lists. Customer list growth is important for our business since a customer’s send volume will increase as they begin mailing to new contacts and lists.

The KPIs your company pays most attention to will always depend on your business model and the goals of your API program. With VerticalResponse, we have a ‘Freemium’ model for email sends (customers with 1000 contacts or less in their email list can send up to 4x/month for free, paid tiers as list size increases) and our API is open and free to access. Thus, we are most concerned with usage and customer growth, through providing an easy-to-work-with and digestible API. Thanks to Mashery’s API Management platform we’re able to effectively track developer registrations, call volume, and API tokens and track these back to integration usage and revenue.

If you’d like to check out VerticalResponse’s Developer Portal, check it out here. Check out our Integrations Marketplace here.