Free tools for web developers

Find broken links on web sites

Link Sleuth is a Windows application that lets you check all of the links on your site to make sure there are no broken links. You can customize the analysis and it generates a report in HTML for you.

http://home.snafu.de/tilman/xenulink.html

Copy web sites

It allows you to download a World Wide Web site from the Internet to a local directory, building recursively all directories, getting HTML, images, and other files from the server to your computer. HTTrack arranges the original site's relative link-structure. Simply open a page of the "mirrored" website in your browser, and you can browse the site from link to link, as if you were viewing it online. HTTrack can also update an existing mirrored site, and resume interrupted downloads. HTTrack is fully configurable, and has an integrated help system.

http://www.httrack.com/

VB <-> C# Converter

http://converter.telerik.com/

Find out what websites are built with

If you want to know what technology has been used to build a certain site, you can use this site to find out.

http://builtwith.com/

Can I use

"Can I use" provides up-to-date browser support tables for support of front-end web technologies on desktop and mobile web browsers. It is a very handy tool when you want to check if a certain html or CSS tag will be compatible for the browsers you need to support.

http://caniuse.com/

WebPageTest

WebPageTest is a free tool which checks the speed and performance of your site. It gives you ratings for different aspects and tells you what you need to do to improve.

http://www.webpagetest.org/

LINQPad

LINQPad is ideal if you find some code on the internet that you want to quickly test, or if you want to play with the new features in C# 6 without having to set up a windows console/forms app or website. It is a windows application

http://www.linqpad.net/

Lorempixel

Lorempixel gives you real placeholder images to use in your site concepts or examples. It randomly picks an image each time the page loads. You can request the images at your own custom size.

http://lorempixel.com/

Jpeg Mini

Reduce image size by up to 80%, without compromising quality

http://www.jpegmini.com

Google PageSpeed Insights

PageSpeed Insights measures the performance of a page for mobile and desktop devices. It fetches the url twice, once with a mobile user-agent, and once with a desktop user-agent.

https://developers.google.com/speed/pagespeed/insights/