Diagnostic.css is a stylesheet which allows the user to test for common errors in a page's markup.
Chrome extension for detecting and simulating frontend Single Points Of Failure. Detects likely third-party single points of failure as you browse and allows you to Simulate 3rd party resources being unavailable.
Also, here: https://chrome.google.com/webstore/detail/spof-o-matic/plikhggfbplemddobondkeogomgoodeg
Burp Suite is an integrated platform for performing security testing of web applications. Its various tools work seamlessly together to support the entire testing process, from initial mapping and analysis of an application's attack surface, through to finding and exploiting security vulnerabilities.
A self-hosted, web-based application for stream your music, everywhere.
Beautiful transformable icons
built for the web.
Guacamole is a clientless remote desktop gateway. It supports standard protocols like VNC and RDP.
We call it clientless because no plugins or client software are required.
Thanks to HTML5, once Guacamole is installed on a server, all you need to access your desktops is a web browser.
The Zed Attack Proxy (ZAP) is an easy to use integrated penetration testing tool for finding vulnerabilities in web applications.
It is designed to be used by people with a wide range of security experience and as such is ideal for developers and functional testers who are new to penetration testing.
ZAP provides automated scanners as well as a set of tools that allow you to find security vulnerabilities manually.
PhantomJS-based web performance metrics collector and monitoring tool
North is a set of standards and best practices for developing modern web based properties. Included are standards and best practices for all aspects of a project, from kick off through development. North encourages an agile, content-first, approach to product development and a mobile-first, in-browser, system based approach to design and development.
localForage is a handy library that improves the offline experience of your web app by using asynchronous storage (via IndexedDB or WebSQL where available) but with a simple, localStorage-like API.
Beautiful text chat for your community.
Scrollback hosts rooms that can be easily embedded on any website.
Turn websites into structured APIs from your browser in seconds
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is damn vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, help web developers better understand the processes of securing web applications and aid teachers/students to teach/learn web application security in a class room environment.
A flexible web app showing vulnerabilities such as cross site scripting, sql injections, and session management issues. Helpful to IT auditors honing web security skills and setting up 'capture the flag'.
YSlow for PhantomJS
Catches mail and serves it through a dream.
MailCatcher runs a super simple SMTP server which catches any message sent to it to display in a web interface.
Phalcon is a web framework implemented as a C extension offering high performance and lower resource consumption.
Web Platform Docs is a community-driven site that aims to become a comprehensive and authoritative source for web developer documentation.
A Dark Pattern is a type of user interface that has been carefully crafted to trick users into doing things, such as buying insurance with their purchase or signing up for recurring bills.
Nice write-up on techniques for scaling up a web application.