San Francisco-based infrastructure-as-a-service startup PubNub raised $23 million in Series D funding to build its international business, specifically in emerging markets. This brings the company’s funding to date to a little short of $70 million.

Hewlett Packard Enterprise (HPE) joined existing investors Sapphire Ventures (which is backed by SAP), Relay Ventures, Scale Venture Partners, Cisco Investment, Bosch, and Ericsson in the latest round.

Founded in 2010 by Todd Greene, now CEO, and Stephen Blum, now CTO, PubNub builds software and hardware for developers to build real-time web, mobile, and IoT applications. Its core product is a real-time publish/subscribe messaging API that is built on its global Data Stream Network (DSN).

“Three billion people now have smartphones, most with virtually unlimited data. Most people use their phones to read content, watch videos, and send emails. Yet the most exciting uses of our phones happens when we leverage that real-time connection to the internet,” said Green. “These applications fit into a new, fast-growing category of applications called connected shared experiences. And PubNub was launched to deliver the new technology required to build connected shared experiences.”

Greene says the startup will use the new funding to “accelerate growth.” It plans to open offices near current and future global customers in the next 90 days, this includes offices in London and in the Asia-Pacific region. It will also use the investment to further build its research and development, and sales and marketing efforts.

PubNub's infrastructure and software are use case-agnostic, Greene said. Meaning, it can be used beyond just chat applications including geotracking, IoT device control and monitoring, live audience participation, data visualizations, and alerts and notifications.

The company's DSN platform is at the core of how it powers these connected shared experiences applications. According to Greene, this layer of technology brings connectivity to any device, anywhere, and it delivers data — reliably, securely, and quickly — at “massive scale.”

The network is made up of 15 data centers spread across North America, South America, Europe, and Asia. These points of presence (PoP) are capable of handling hundreds and millions of device connections and trillions of messages.

PubNub also delivers a messaging and edge compute platform. The messaging platform is comprised of DSN alongside its real-time APIs. It provides features for publish/subscribe messaging, establishing presence, storage, and a stream controller. This feature allows developers to build and enhance real-time messaging and features into applications.

The edge compute platform, or PubNub functions, lives inside the messaging platform and allows developers to “to manipulate, augment, transform, reroute those real-time messages at the edge, no additional servers required. You could translate a chat message, monitor IoT sensor readings for anomalies and trigger an alert, send an SMS if something happened,” said Greene.

This infrastructure and the APIs behind it are meant to solve three key challenges of building and scaling these applications: connecting any number of devices for secure, always-on connectivity; delivering messages in under a quarter of a second; and controlling the real-time streams of data to manipulate, filter, and augment data as it flows through its network using serverless compute at the edge.

All of this runs as an overlay on the public cloud. It relies on a mixture of Amazon Web Services (AWS) and others, according to Greene. The company has partnerships with AWS as well as Microsoft Azure and IBM Watson.