Is there a way to look up someone's profile with GET request?

... yes?
https://e621.net/users/1182633.json

Yes, You just need to add ".json" at the end of user profile endpoint.

Example request:

https://e621.net/users/1182633.json

Respond:

{
  "wiki_page_version_count": 0,
  "artist_version_count": 0,
  "pool_version_count": 0,
  "forum_post_count": 1,
  "comment_count": 0,
  "flag_count": 0,
  "positive_feedback_count": 0,
  "neutral_feedback_count": 0,
  "negative_feedback_count": 0,
  "upload_limit": 10,
  "id": 1182633,
  "created_at": "2022-04-17T22:02:17.872+02:00",
  "name": "wasduwu",
  "level": 20,
  "base_upload_limit": 10,
  "post_upload_count": 0,
  "post_update_count": 0,
  "note_update_count": 0,
  "is_banned": false,
  "can_approve_posts": false,
  "can_upload_free": false,
  "level_string": "Member",
  "avatar_id": null
}

Note, that if You do request as logged user, there will be extra fields like e-mail address, account settings etc.

Tip: if something is not documented in the API here, You can also search for documentation on Danbooru API Wiki , as this site is based on it.

bitwolfy said:
... yes?
https://e621.net/users/1182633.json

thank you!