If you're a software engineer (or will work closely w/ engineers), I built Key Values (https://www.keyvalues.com) to help w/ this.
Before building KV though, my research process included looking for and reading:
- the company's career and about us pages
- an active blog w/ recent posts (w/in the last 2 months)
- LinkedIn / Twitter / GitHub of founders and existing team members (I'd also look for any old blogs written by (or press written about) these folks before they joined the company)
- checking to see if the company hosts meetups or hackathons I can attend
- seeing if I know anyone who currently works there or worked there before and then reaching out
Before building KV though, my research process included looking for and reading:
- the company's career and about us pages
- an active blog w/ recent posts (w/in the last 2 months)
- LinkedIn / Twitter / GitHub of founders and existing team members (I'd also look for any old blogs written by (or press written about) these folks before they joined the company)
- checking to see if the company hosts meetups or hackathons I can attend
- seeing if I know anyone who currently works there or worked there before and then reaching out
- cold emailing or Tweeting current team members