Stoplight

Stoplight is an API design and documentation platform founded in 2015 and headquartered in Austin, Texas, that pioneered the design-first API development workflow in which teams define their OpenAPI specification before writing any implementation code. The platform provides a visual API designer that generates valid OpenAPI without requiring knowledge of the YAML syntax, lowering the barrier for product managers and non-engineering stakeholders to participate in API design reviews. Stoplight Studio, its desktop and web editor, includes an integrated mock server that automatically generates realistic API responses from the spec so frontend teams can begin integration work before the backend is built, accelerating parallel development. The platform also offers a style guide and linting engine called Spectral — an open-source project Stoplight maintains — that allows organizations to encode API design rules and automatically check specs for consistency across teams. Stoplight was acquired by SmartBear Software in 2021, joining a portfolio of API tools including SoapUI, SwaggerHub, and Pactflow, which gave the company enterprise distribution and integration into broader API lifecycle workflows. The company competes with Redocly, ReadMe, and Postman in the API design and documentation segment, with its visual designer and design-first methodology being its primary differentiator for organizations standardizing their API development process.