Firebug is always just a keystroke away, but it never gets in your way. You can open Firebug in a separate window, or as a bar at the bottom of your browser. Firebug also gives you fine-grained control over which websites you want to enable it for.
sunpack-n emulates browser functionality when visiting a URL. It's purpose is to detect exploits that target browser and browser plug-in vulnerabilities. It accepts many different types of input:
PDF files - samples/sample-pdf.file
Packet Captures - samples/sample-http-exploit.pcap
All of the source code is completely free and open, available on the github under MIT licence,
and we have a command-line version, python library and a node package as well.
SAFARI WEB INSPECTOR
Web Inspector is an open source web development tool built into Safari that makes it easy to prototype, optimize, and debug your web content on iOS and OS X.
Turn to Web Inspector when your front-end logic goes awry. Web Inspector offers a debugging environment that lets you pause script execution and observe the values of your variables as they are defined.