I was thinking it's an unnecessary complication, but I forgot about the base64 encoding. If you're hardcore you could just do that yourself:

```
"https://basecamp.com/123/*": {
    "headers": {
        "authorization": "Basic YmlsbHlAZXhhbXBsZS5jb206cGFzc3dvcmQ="
    }
}
```

And it should still work for individual resources:

```
https://billy%40example.com:password@basecamp.com/123/api/v1/projects.json
```

But of course avoiding that is the point of these options anyway.

The convenience of the base64 encoding is worth keeping it, but the key could be more descriptive to disambiguate it from `auth.json`. The docs cover it, but what about `basic-auth` at least? `credentials` would work even better I think.