I've tried PUT and POST - PUT gives me a 403 forbidden and POST gives 405 method not allowed. I am passing my client id. Other endpoints work so I think it's just this end point that is broken.
Each client must register their application and receive the client_id and client_secret.
For public read-only and anonymous resources, such as getting image info, looking up user comments, creating an anonymous album, etc. all you need to do is send an authorization header with your client_id along with your requests. This also works if you'd like to upload images anonymously (without the image being tied to an account). This lets us know which application is accessing the API.
Authorization: Client-ID YOUR_CLIENT_ID
I was previously able to upload images, then create an album containing those images anonymously. After I uploaded 50 I hit a rate limit--the User one, IIRC--which prevented me from using the API as I needed.
Today I'm able to upload more than 50 images, but I get a 403 error when attempting to create an album.
$ wget -O logo.png https://cdn.shopify.com/s/files/1/0179/5445/t/2/assets/logo.png?201
$ curl -b /tmp/imgur.jar -c /tmp/imgur.jar -H 'Authorization: Client-ID 4af97bc6fa5bf6b' -XPOST https://api.imgur.com/3/image -Fimage=@logo.png
{"data":"id":"4YG3gJo","deletehash":"tR3VmVHWJO8wdwU","link":"http:\/\/i.imgur.com\/4YG3gJo.png"},"success":true,"status":200}
$ curl -b /tmp/imgur.jar -c /tmp/imgur.jar -H 'Authorization: Client-ID 4af97bc6fa5bf6b' -XPOST https://api.imgur.com/3/album --data ids[]=4YG3gJo
{"data":{"error":"Unauthorized","request":"\/3\/album","parameters":"ids = Array","method":"POST"},"success":false,"status":403}