Other programs require you to go fullscreen to have a borderless experience.  Highbrow windows are always borderless.  It's like looking at snapshots on your desktop.

You can have as many image browsers open on the screen as you want, with your real-estate used to maximum effect.

Highbrow windows snap to each other's edges, to make it easier to fill the screen with the images you love, arranged in the way that you want.

Navigate with keyboard, mouse, or trackpad. Click, swipe, or tap to see the next image. Just hit the spacebar to start a slideshow. 

You can also pinch to zoom, and use the corners of the windows to resize the image. Right click on the image for additional commands. Rows of buttons aren't necessary.

The current set of open windows can be saved and reloaded easily from the menu bar.  The list of saved states is searchable, sortable, and just a little bit awesome.

You can tag your states however you want to make them easier to find later.

With almost no interface, Highbrow looks good in both light and dark mode, and lets your pictures speak for themselves.

Despite the minimalist interface, Highbrow features a full image browser in each window.  The browser sidebar can be shown or hidden independently for each window.

Highbrow windows can be set to run at the desktop level, so you can have a screenshow (or a couple of screenshows) running behind your work.

You can also set Highbrow windows to float on top of other windows, if you want them to always be visible.

You can rename & delete files and folders directly from Highbrow, as well as copying and moving files, so you don't have to switch to the Finder to manage your image collection.

Highbrow's behavior can be customized to your liking, including but not limited to: hiding the menu bar and dock (or not), the strength with which windows snap to each other's edges, and whether Highbrow includes the contents of subfolders in its list of images, or opens the subfolders in their own windows.

Highbrow does not move your photos to a proprietary database.  It accesses your images in the normal folder structure in OS X, so you have the freedom to store your photos where you want.  (Though maybe not in the New York harbor.)