For Chrome, Javascript Errors Notifier, Cookies and Cookie Inspector (two different extensions... I like Cookies better, but there's a weird bug in it that annoys me), Advanced REST Client.
vi for my text editor
Aptana Studio 3 IDE for PHP development (sadly, this is a defunct product... it had a lot of promise, and is still pretty good, but doesn't deal with modern PHP versions, but I like it... so there.)
OneNote to cover lots of miscellaneous things (sys admin notes, documentation for processes, clients who are use our SFTP and their related info, etc.)
Mattermost hosted in-house for chat with my team members (only the enterprise version of Slack is HIPAA-compliant, and for the little bit we would use it, not worth it)
Good ol' pen and paper for my to-do list. Nothing else works quite as well, as quick and as flexible (for me... I'm a simple man.)
jsonlint.com for JSON validation (finding that pesky odd character can be a pain sometimes!!!)
Edit: Forgot one important one: snippingtool - a little Window utility that lets me clip an area of the screen for a screenshot.