jbalde

UserAgent Theme Switcher is a simple plugin which lets you change the theme to be displayed according to the detected browser.
Checks from a predefined list useragent so that the user can at will change the theme shown for that browser. 
A user can configure a special theme for example for mobile phones that is lighter and this adapted to these devices
Ideal for displaying themes ready to opera mobile, internet explorer mobile, iphone, android, etc.
Now the cache is not supported but will work so that if it is supported in the future

UserAgent Theme Switcher

UserAgent Theme Switcher is a simple plugin which lets you change the theme to be displayed according to the detected browser

SwiftNinjaPro

This plugin blocks non-admin users from using inspect element, while still allowing access those with manage_options permission. 
The plugin also blocks some of the common keys(f12, ect.) and optionally can block right-clicks for non-admin users. 
Admins are unaffected by the plugin entirely. This plugin is also able to block users who open developer tools on another site, before visiting your site.
Version 3.0 update
This plugin is now fast and accurate, and should work on most browsers. 
This plugin can detect the browser console based on lag increased by opening the console. This detection is tough for a browser to prevent or get around. 
The detection runs fast, and has some resistance to lag spikes.
Lag detection does mean your site needs to have ok performance, but when testing it, I could play 10 of 10 youtube videos all at once without a false positive. 
During my tests, detection was still within the second I open dev tools, and successful if I go to the page with it already open. 
I tested this in chrome, firefox, and chromium. 
I also tested this on my somewhat slow website with tons of wordpress plugins installed (and the 10 videos at once test) without false positives.

Developer Tools Blocker

This plugin blocks non-admin users from using inspect element, while still allowing access those with manage_options permission.

UserAgent Theme Switcher vs Developer Tools Blocker