I believe all people who are reading this post know how useful OpenAPI/Swagger specs are. However, the majority of tooling is built for API owners to help them power things like docs, SDK generation, API consoles, etc. And what about API consumers? They are considered to use only SDKs. But, that is changing right now.
API definitions can now be used with:
And more usage scenarios are coming in the near future. From our point of view, the main limiting factor for the ecosystem growth is the scarcity of OpenAPI specs for public APIs. This is the problem APIs.guru tries to solve:
You can check our cozy collection of OpenAPI specs:
If you're interested in access to the whole collection, you can use our simple REST API; no API key or registration are required. So nothing limits your creativity on what you can do with those specs and below are just a few examples of existing integrations:
If you work on OpenAPI tool/library, consider using APIs.guru as a test suite and don't forget to add our eye-grabbing README badge: 
We go beyond simply collecting API specs and try to solve as many common API definitions problems as possible:
Frankly speaking, searching for specs is hard work. So we need your help. If you are API owner or if you just know about an API specification for public API in any popular format (WADL, RAML, Swagger, API Blueprint) consider adding it to our collection:
As an open-source project, we are working on building a community. Feel free to chat with us in Gitter or open an issue on Github. Follow us on Twitter. And don't miss an opportunity to become a contributor: we have a few issues you can help with.