Polarr Photo Editor is a powerful free image editor for Chrome.
Once installed, hovering your mouse over an image displays a Polarr icon, and clicking this opens the picture in the editor.
You can also import photos from URLs, or your own computer, with limited support for some RAW formats (it opens their high-def JPEG only).
A left-hand toolbar displays previews of your image using various filters - "Focal", "Warmth", "Cinematic" and so on - and clicking any of these applies the settings immediately.
Not quite right? No problem, because a right-hand toolbar displays a host of fine-tuning options, with tweaks for temperature, tint, exposure, gamma, contrast, highlights, shadows, whites, blacks, clarity, vibrance, saturation, HSL, sharpness, denoising, grain, vignette, chromatic shift.
You even get tone curve adjustments, with a histogram for guidance.
There are options to use radial or graduated filters, and you're able to combine multiple filters to deliver the effect you need.
This can get complex, but fortunately you're able to save your current settings as a custom filter for speedy reuse later.
You also get crop, rotate, and a handy straighten tool, amongst other useful options, and finished images may be saved locally or exported to Facebook, Dropbox, Flickr, Google Drive, Picasa, Box and Evernote.
Polarr can also be used from any browser at its website, and the company offers commercial apps for Android, Windows 10, iOS and Blackberry.
Update in 4.0.1: New interactive step-by-step tutorials to teach you photo editing basics.
An excellent photo editor which crams in a vast amount of image-tweaking options, while remaining generally very easy to use.