I used to spend 20 minutes a day on chores that should take 20 seconds. Reformatting JSON someone pasted into Slack. Guessing whether a hex color was the right shade. Converting epoch timestamps in my head. Then I started collecting browser-based developer tools -- and that 20 minutes went away.
Here's the thing: this isn't a list of "10 tools you should know." It's a list that maps to specific frustrating moments I've had this year. Every one of these saved me at least once.
JSON formatter: Not because I don't know how JSON works -- because no one should read a 4 KB one-liner in a log file. This is the tool I reach for when an API returns minified JSON and I need to find which key changed.
Regex tester: Every dev has a regex war story. Mine was a one-liner that was "supposed to validate email addresses" and instead took 45 seconds to fail catastrophically.
Base converter: You'll need this when a hardware datasheet lists a register as 0x3F8E and you need to flip bit 23.
The shared theme: Every tool here eliminates a repetitive task so you can focus on actual problems. They run in the browser, process data locally, and need zero setup.