Like swagger/swashbuckle but for node.js?

I've been looking into this as well, the project which will help you is swagger-node-express. swagger-ui, should come as a dependency of swagger-node-express. Swagger-node-express wraps express and exposes it as a new interface meaning there will be code changes you to make it work. This is what a route would look like (taken from their docs)

 var findById = {  'spec': {    "description" : "Operations about pets",    "path" : "/pet.{format}/{petId}",    "notes" : "Returns a pet based on ID",    "summary" : "Find pet by ID",    "method": "GET",    "parameters" : [swagger.pathParam("petId", "ID of pet that needs to be fetched", "string")],    "type" : "Pet",    "errorResponses" : [swagger.errors.invalid('id'), swagger.errors.notFound('pet')],    "nickname" : "getPetById"  },  'action': function (req,res) {    if (!req.params.petId) {      throw swagger.errors.invalid('id');    }    var id = parseInt(req.params.petId);    var pet = petData.getPetById(id);    if (pet) {      res.send(JSON.stringify(pet));    } else {      throw swagger.errors.notFound('pet');    }  }};

Where the type "Pet" is still for you to define, I wont rewrite their docs here.

This will then produce a file which swagger-ui can use to give you a self contained self documenting system. The documentation for swagger-node-express is more than good enough to get it setup (dont forget to set swagger path, I did).

swagger.configureSwaggerPaths("", "/docs", "");

Having shown you the tools that in theory offer what your asking for, let me explain why I've come to conclusion that I'm not going to use them.

1. A lot of code change needed - is it really less work than creatingyour own swagger.yml file? I dont think so.
2. Hand creating a swagger.yml file is much less likely to brake your project.
3. Whilst swagger-node-express hasnt been depricated it's github repo doesnt exist anymore, its been wrapped into swagger-node, but that project doesnt really mention it
4. I'd be wary of any tool that means I need to wrap express - it's not something I'd look to do.

TL;DR:It's possible with a lot of code change - probably not what your after though.