Option to auto-stabilize so your pictures are perfectly level no matter what (see example image).
* Expose your camera's functionality: support for focus modes, scene modes, color effects, white balance, ISO, exposure compensation/lock, face detection, torch.
* Video recording (including HD).
* Handy remote controls: timer (with optional voice countdown), auto-repeat mode (with configurable delay).
* Option to take photo remotely by making a noise (e.g., voice, whistle), or by voice command "cheese".
* Configurable volume keys.
* Optimise GUI for left or right-handed users.
* Zoom via multi-touch gesture and single-touch control.
* Option to lock orientation to portrait or landscape for photo or video. Upside-down preview option for use with attachable lenses.
* Choice of save folder (including support for Storage Access Framework).
* Disable shutter sound.
* Overlay a choice of grids and crop guides.
* Optional GPS location tagging (geotagging) of photos and videos; for photos this includes compass direction (GPSImgDirection, GPSImgDirectionRef).
* Apply date and timestamp, location coordinates, and custom text to photos; store date/time and location as video subtitles (.SRT).
* Yes you can take a selfie (also known as front camera), includes support for "screen flash".
* Support for (some) external microphones.
* Widget to automatically take a photo after launching.
* Support for HDR and Exposure Bracketing.
* Support for Camera2 API: manual focus distance; manual ISO; manual exposure time; manual white balance temperature; RAW (DNG) files.
* Dynamic range optimisation mode.
* Small file size.
* Completely free, and no ads in the app (I only run ads on the website). Open Source.