OpenAPI

OpenAPI Specification (OAS) provides a vendor-neutral, language-agnostic interface description format for modern REST APIs, using JSON or YAML.

OpenAPI defines a standard, machine-readable format for describing HTTP APIs: this is the core value proposition. The specification, currently at version 3.1.0, allows both humans and computers to understand a service's capabilities without source code access. An OpenAPI Description (OAD) drives critical tooling: it enables automated documentation generation, facilitates client and server code creation (SDKs), and streamlines testing workflows. Governed by the OpenAPI Initiative (OAI) under the Linux Foundation, it ensures a robust, open standard, maximizing interoperability and minimizing guesswork in API consumption.

https://www.openapis.org