OpenAPI Generator - OpenAPI Generator enables you to generate documentation, clients, and servers from OpenAPI 2.0/3.x documents without hassle.
XMLable - XMLable is an online toolbox designed for working with XML, offering tools such as a formatter, validator, comparator, generator, XPath tester, XSD generator, and XSL transformation.
Widdershins - Widdershins is an open-source, easy to use Semoasa/ OpenAPI/ AsyncAPI/ definition to ReSlate/Slate compatible markdown released under the MIT License.
JSONFormatter.org - Online JSON Formatter and JSON Validator will format JSON data, and helps to validate, convert JSON to XML, JSON to CSV. Save and Share JSON
API Spec Converter - API Spec Converter is an open-source solution that enables you to transform API descriptions between major formats like WADL, OpenAPI (fka Swagger), API Blueprint, RAML, and more.
FreeFormatter - Freeformatter is a platform that contains free online tools for developers, including formatters (json, html, xml, sql, etc.), minifiers (css, javascript), compactors, validators, and much more.