Stainless is disrupting the world of software development by using AI to automatically generate Software Development Kits (SDKs) from APIs. This innovative approach simplifies the process for developers by allowing them to bypass the traditional, manual SDK creation process and instead, rely on a compiler-driven system that generates SDKs in multiple programming languages on the fly.
API users often face a significant challenge when vendors only offer APIs, which are essentially protocols that facilitate communication between software components. Without an SDK, developers are required to dig through API documentation and build the integration themselves. However, crafting an SDK at scale can be a daunting task for vendors. Stainless aims to solve this problem by offering a platform that generates SDKs in popular programming languages like Python, TypeScript, Kotlin, and Go. As APIs evolve, Stainless ensures that SDKs remain up-to-date, providing versioning and changelog updates to keep everything synchronized.
Alex Rattray, the founder of Stainless, explained that unlike the typical approach where companies have in-house developers manually building libraries to connect APIs, Stainless leverages AI to produce an initial configuration. This configuration can then be fine-tuned to meet the specific needs of the API. Rattray highlights that this process avoids common issues like inconsistent or outdated libraries, streamlining integration and accelerating development timelines.
Rattray’s background in the industry deeply informs Stainless’ approach. Having previously worked at Stripe on the developer platform team, he gained invaluable insights into the challenges of API documentation and SDK generation. At Stripe, he helped revamp API documentation and contributed to the system that powers Stripe’s API client SDK, laying the foundation for Stainless’ platform.
While Stainless is not the only company in the API-to-SDK generator space, it stands out for its “polish,” according to Rattray. Competing platforms like LibLab, Speakeasy, and the OpenAPI Generator have been criticized for delivering low-quality code outputs, often requiring significant work to clean up and refine the generated SDKs. In contrast, Stainless aims to deliver high-quality SDKs with minimal post-generation editing, a key differentiator that has attracted major tech companies, including OpenAI, Anthropic, Meta, and Cloudflare.
Stainless has gained significant traction, with hundreds of paying customers and its SDKs being downloaded tens of millions of times weekly. The platform offers a free tier for publishing a single SDK, but companies must pay between $250 a month and $30,000 per year for more advanced features, such as the ability to generate multiple SDKs across various programming languages. Stainless’ enterprise tier provides additional AI-specific functionality and white-glove services.
The company has seen strong financial growth, with annual recurring revenue nearing $1 million. Recently, Stainless closed a $25 million Series A funding round, led by a16z and supported by investors like Sequoia, MongoDB, and Zapier. This brings the company’s total funding to around $35 million. The new funds will be used to expand Stainless’ 20-person team and accelerate the development of its platform.
Rattray envisions Stainless as more than just an SDK generator. He aims to build a comprehensive platform that developers turn to for everything API-related. With the growing importance of APIs as the primary interface for businesses, Stainless is positioning itself to meet the increasing demand for efficient and scalable API solutions, making it a pivotal tool for the future of software development.
