SDK vs API: Which One Should You Provide to Developers? Written by: Brant Partington Developers are the lifeblood of your tech ecosystem. If they can’t use your tools easily, your brilliant functionality might go unused. The tools you offer—like APIs or SDKs—shape how developers interact with your services and whether they stick around. Understanding the difference between APIs and SDKs, and knowing when to offer each, isn’t just helpful—it’s essential. Developers influence product decisions, and in the fiercely competitive tech space, their experience can make or break your adoption. This article breaks down APIs and SDKs, highlights their differences, and helps you decide which will best serve your developer community. What is an API? APIs (Application Programming Interfaces) are the language-agnostic means that allow developers to interact with your technology. APIs are services with strongly defined contracts (called API specifications) that detail both the interaction protocols, as well as the data sent to and/or received from your services. Often, API specifications are defined using OpenAPI (formerly called Swagger) specifications, which is a way to define your API’s contracts. API specifications also frequently provide the initial documentation for your APIs through the use of documentation generation tools, such as ReadMe’s OpenAPI Upload Support. After uploading your OpenAPI specification, ReadMe automatically generates API documentation that provides developers with the information they need to integrate with your APIs. ReadMe then allows you to customize the documentation using our easy-to-use WYSIWYG editor. ReadMe also enables both technical and non-technical users to suggest edits and collaborate on API documentation, reducing friction in documentation processes. What is an SDK? An SDK (Software Development Kit) is an add-on to APIs that makes your APIs easier to consume. SDKs include foundational building blocks to give developers a head start in using technology services. They provide benefits to an API consumer above and beyond the APIs themselves. To use a metaphor, an SDK is like buying a bagged salad kit. The salad kit provides everything you need to serve a specific salad, making your life easier. For example, an SDK might provide data object structures in a particular language used in your APIs which a developer could leverage. Or, an SDK could provide the underlying network support to call your APIs from a particular language. It can also streamline business interactions, such as consolidating a few different API calls into a single interaction with the SDK. However, you could forgo the salad kit, and make the salad by buying and preparing the individual ingredients. You could even change the ingredients to your preference, similar to integrating directly to a set of APIs. SDK vs API: how to choose At the end of the day, the question is not whether you should provide API vs SDK. Instead, the question is whether or not SDKs will benefit developers. Developers need APIs to access your tech services. Without them, developers are limited in their interaction with your service. APIs give developers the flexibility to integrate with your services from any programming language and perhaps even in use cases you haven’t thought of yet. An example would be developers needing to provide Proof of Concepts (PoCs) and validate API sequencing using efficiency tools like ReadMe’s TryIt! functionality. It lets you quickly and easily kick the tires on API functionality without writing a line of code. And to leverage it, you must offer a functional and testable API. Without APIs, users are only able to access your services when on your company-hosted assets, such as mobile apps or your website. But let’s go back to SDKs. How does this technology benefit developers specifically? Here are two pros of using SDKs. SDK pro: programming language-specific data structures SDKs simplify the amount of work it takes to create and/or consume data structures from APIs. Without an SDK, developers must spend time translating to/from their own data structures from/to the data structures defined in the API specifications. APIs are simply http/https endpoints. They receive and provide data in a programming language-agnostic manner. (I.e. it doesn’t matter what development language the client is built in). While being flexible, this does add work for developers to translate to the API language. This is a difference between SDK and API, as SDKs are generally provided in common programming languages, such as JavaScript, Java, or Python. They provide the objects needed by applications to use the services. This allows developers to focus on using the functionality exposed via API instead of spending time on the translations. SDK pro: business logic optimization Technology services generally architect APIs to complete one transaction or one unit of work. This approach best allows for a service-oriented architecture (SOA) in which services may be consumed for a single task. Each service can be leveraged from any number of clients (internally and externally). But depending on the complexity of the API interaction, this can be confusing to developers who aren’t subject matter experts. This complexity could cause developers a lot of extra work to figure out the proper interaction, especially if API documentation is not clear and thorough. Pro tip: Check out our guide to API documentation to understand why it’s a necessity. Also, if you have trouble keeping your API documentation up-to-date, ReadMe offers better version control for workflow management, ensuring documentation stays accurate and accessible across different API versions. Further, developers may need to redo their work if they believe it to work one way, but discover their mistake late in development. In either case, the developer is left frustrated. In these complex scenarios, providing an SDK to consolidate these interactions is valuable. The SDK could link together a series of actions, or provide some decision-making based upon common scenarios for a particular client type (e.g. a mobile app). Again, these SDKs would be programming language-specific, giving the developer a jump start to getting the API interaction as intended. Why SDKs Aren’t Always the Best Option It might seem like providing SDKs is a no-brainer—they save developers time and effort, right? Not so fast. Maintaining SDKs can be costly and time-consuming Providing SDKs requires an investment of resources. You’re not just creating SDKs—you’re responsible for keeping them up-to-date with evolving APIs, which can become a massive, ongoing effort. One approach that helps is using Stainless for automatic SDK generation. ReadMe has an integration with Stainless which automatically updates your API documentation with the Stainless-enhanced OpenAPI spec. Syncing SDKs with API updates delays adoption Every time your API is updated, corresponding SDKs need to be updated too. This delay can frustrate customers who rely on SDKs, as they may be unable to access new API functionality right away, potentially derailing important projects. SDK versioning creates extra work for customers When you release a new SDK version, customers have to test it, integrate it, and account for it in their regression testing and release schedules. This extra maintenance can pull developers away from building new features and slow down their productivity. Third-party code policies may block SDK use Finally, some organizations have strict policies for including third-party code in their code—it’s simply not allowed or must go through extensive privacy and security reviews prior to approval. These concerns may steer developers to integrate directly with published APIs, giving them more flexibility and control over their release processes and version control. Thoughtful SDK delivery At the end of the day, be strategic about your SDKs. Ask yourself these questions: Are SDKs truly saving developers time, or is the maintenance burden canceling out the benefits? Are you offering SDKs in the programming languages your developers actually need? How can you ensure the SDKs are well-documented and easy to use? Will providing SDKs encourage more developers to adopt your product compared to using APIs alone? Are there specific features or functionality that are harder to implement without an SDK? What’s your plan for handling SDK versioning and backward compatibility? Thoughtful answers to these questions will shape a strong SDK strategy. Once your strategy is in place, stay flexible. You can’t pull SDKs once they’re in the wild, but you can ensure they continue to deliver value. Monitor usage closely, gather developer feedback, and be ready to adapt. If an SDK isn’t meeting expectations, don’t hesitate to refine it—or even deprecate it entirely if it’s no longer useful. The key is listening to your developer community and letting their needs guide your decisions.