IoT APIs: A guide to Application Programming Interfaces

Leonardo Gurria
November 29, 2022
Person unlocks electric bike with their phone

IoT devices offer many benefits as they are connected to the internet. This means they collect data and can communicate with other computers and applications. APIs, or applications programming interfaces, are what make it possible to communicate with a connected device, based on a set of rules.

APIs are critical in IoT, both to communicate with the device and to leverage the information from the device, but there is a lot to understand. In this post, we’ll dive into:

What is an IoT API?

The term API (application programming interface) is the tool software developers use to gather and transfer data from one application or computer to another. Or in other words, APIs enable developers to programmatically interact with software components both inside and outside of their own code.

In IoT specifically, APIs are used to gather and transfer data from the connected device to an application or computer. They are also used to instruct a connected device to take a particular action. Because connected devices can be anywhere in the world, having an API makes it possible to remotely access a device and make the data useful.

For Hologram specifically, we gather and transfer usage data via cellular connectivity and share it in the Dashboard. Within the Dashboard, users can remotely pause, activate, or deactivate devices; pull reports; and more. The Hologram API enables users to expand on what’s done in the Dashboard as well as bring connectivity data directly into their own applications or reports.

How do APIs and IoT work together?

An API is a way to enable users to programmatically access information about their devices and make decisions or take actions based on it. There are an endless number of ways they can work together in IoT. A few examples include:

  • Managing a fleet: Everything from activating devices to billing and reporting are all done via the API.
  • Preventing fraud: Leveraging the API enables users to create alerts if a device is moved or if a SIM card was stolen. We’ve also seen users configure SMS limits to prevent high data charges if a device is stolen.

While the Hologram Dashboard surfaces all of this information and capabilities, users will leverage the Hologram API to either bring data into their own tools or leverage it as part of their application for their customers. APIs are powerful tools that take the data created at the device level and make it usable.

What is an API endpoint and why is it important?

An API endpoint is the source which you want to get the data from. In more technical terms, it’s an API call. The most obvious API endpoint in IoT is at the device level, gathering data from the connected device. This collects data usage, connectivity status, and any other additional data an IoT application is intending to collect.

Beyond the device endpoint, there are many other useful endpoints within an IoT deployment. For example, a team may use the API to collect data as it relates to billing, making finance reporting programmatic.

Main types of IoT APIs

There are four common types of APIs: Public, Partner, Internal and Composite.

Public APIs

Public APIs, also known as Open APIs, are available to the public with no restrictions. This enables developers outside of an organization to access data to enhance their own application. Single sign on, using your email or social media account, is made possible through Public APIs, bringing in the email provider or social platform code into your application.

Partner APIs

Partner APIs can be leveraged by a client or partner of an application. These APIs require users to sign in and authenticate with an API key to access the API. The Hologram API is an example of a Partner API, allowing customers to communicate directly with their connected devices and bring data back to their applications.

Internal APIs

APIs used by a company to build and manage their applications are internal or private APIs. This ensures that only those working on a product have access to make changes to a product or to the sensitive data on a platform.

Composite APIs

Composite APIs batch several API requests into a single API call. This reduces the number of trips to a server. By grouping a chain of API calls into one API, a client can make one API request that includes a chain of calls and end with one response.

Types of API architectures and delivery formats

While we discussed the different types of APIs, there are also different approaches in how data is transferred over a network using API calls. REST and SOAP are leading architectures, but offer different benefits to users. JSON and XML are the formats in which the data is delivered.


SOAP (Simple Object Access Protocol) is a protocol specification for exchanging data between two endpoints. SOAP is mostly used for applications that require a high level of security – like payments.


REST, also known as a RESTful API (Representational State Transfer), is an architectural style for building client-server applications. REST supports high-performing and reliable communication at scale, independent of the technology used. It is a more lightweight architecture than SOAP.


JSON and XML are two of the formats in which data is delivered. SOAP relies exclusively on XML while REST allows XML, JSON, HTML, and plain text. JSON is a lightweight, human-readable format that can be used with any programming language. Most public web services use REST APIs with JSON.

Get started with Hologram’s REST API.

Examples of IoT APIs

There are endless applications for IoT APIs. As we mentioned earlier, APIs enable fleet operators to manage an entire IoT deployment. This includes activating and deactivating devices, reporting and more. It also can help users prevent fraud through alerts and data usage limits.

APIs in IoT can also send SMS messages to activate a device. Take for example a scooter. Once a consumer uses their mobile app to start a ride, an API then sends a message to the scooter to activate the ride.

Or, in the case of a remote patient monitoring device, an API can check the last time someone tested a specific health metric and then alert the patient via text or email.

In each of the examples, the API programmatically sends a message based on an action, to enable another action to take place.

Benefits of IoT APIs

APIs are powerful tools. They enable users to communicate with connected devices anywhere in the world – both to send information to and receive data from. Without an API, it would be impossible to run an IoT deployment without having feet on the ground with each device. By programmatically communicating with connected devices they provide a ton of useful data and allow new experiences for consumers.

Harness the power of IoT with Hologram

Combined with Hologram’s reliable connectivity, our API enables you to communicate with connected devices at scale, gaining powerful insights and enabling new experiences. Learn more about how you can get the most out of your IoT deployment with Hologram.

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