API specs: Swagger/OpenAPI, WADL, RAML

Microsoft Azure AI APIs have specs in Swagger (JSON), WADL (XML) and "English" format.
Cognitive Services APIs Reference

Cognitive Services for Language REST API reference | Microsoft Learn

Text Analysis Runtime - Analyze Text - REST API (Azure Cognitive Services - Language) | Microsoft Learn

Getting Started with Swagger [I] - What is Swagger?

Another approach is to use WADL, which can be generated by some tools. In this case, it’s machine-readable, but definitely not human-readable. Also, writing a WADL manually is a tedious process.

Web Application Description Language

Ask HN: Why did OpenAPI become more popular than WADL? | Hacker News

Comparison of WSDL & OpenAPI API Documentation Formats

RAML (software) - Wikipedia

RESTful API Modeling Language (RAML) is a YAML-based language for describing static APIs (but not REST APIs).

raml-org/raml-spec: RAML Specification

Welcome | RAML

Top Specification Formats for REST APIs | Nordic APIs |

Revisiting the features offered in WADL, RAML, and Swagger - RESTful Java Web Services - Second Edition [Book]

Features	WADL	RAML	Swagger
Release date	2009	2013	2011
File format	XML	RAML	JSON/YAML
Open source	Yes	Yes	Yes
Commercial offering	No	Yes	Yes
Language support	Java	JS, Java, Node, PHP, Python, and Ruby	Clojure, Go, JS, Java, .Net, Node, PHP, Python, Ruby, and Scala
Authentication	No	Basic, Digest, OAuth 1, and OAuth 2	Basic, API Key, and OAuth 2
API console	No	Yes	Yes
Code generation for server (Java)	No	Yes	Yes
Code generation for client (Java)	Yes	Yes	Yes