Reels download as MP4 at the resolution they were uploaded in, with no watermark layered on top. Many downloader sites stamp their own logo onto the video — we never do.
Posts work the same way, covering both photo and video posts.
Audio can be extracted from any reel as MP3, which is useful when you want a trending sound rather than the video.
Profile pictures download at full size, far larger than the version Instagram shows on screen.
One limitation worth knowing: only public content can be downloaded. If an account is private, its reels and posts aren't accessible to anyone who isn't an approved follower, and no tool can change that.