- Fiddler Tool – sniffs your HTTP requests so you can really see what’s going on (download free at www.fiddlertool.com)
- IE Web Developer Toolbar – get it for your sanity
- Web Developer Extension – lets you toggle JS/CSS, change forms on the fly, clear cache, outline DOM elements, resize the window to emulate various resolutions, etc. (go to to get it)
- Live HTTP Headers - don't trust your intuition: use this to sniff requests and responses so you can see what URLs are really getting hit, what the cache and auth settings really are, etc.
- JSEclipse plugin – syntax highlighting, code completion, etc. (add it to your Eclipse Update list by following the instructions)