Images look blurry in browser

Have you tried making images specifically to the dimensions they will have online, I mean the pixel dimensions? 

Once you've done that, try a little sharpening - that should help a lot.

If you're perhaps working with large images and placing those online so the browser is scaling - that could explain the reduction in sharpness. 

edited, typos!!

I hope this helps
neil barstow, colourmanagement net :: adobe forum volunteer:: co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management

I'm guessing you have a retina screen?

In that case the browser will scale up images, so that one image pixel is represented by four screen pixels.

Photoshop displays correctly, one image pixel represented by exactly one screen pixel.

Many things can cause this issue including your site template, for example. After exporting image from Photoshop, open it in some image viewer at 100%.

Does it look sharp? Its not Photoshop then.

Does not look sharp at 100% view? Which command and settings you are using to export or save?

You should show us a screenshot. The most plausible cause is, that the browser image is too small for the display. You also may have zoomed your browser, to have a bigger view on a smaller high-resolution screen.

If you have a specific website, you could also give that to us. Don't forget to tell us the dimensions of your pictures.