Ask HN: Founders, what was the major sourcing channel for your first 100 users?

Linkedin for a B2P product. I posted a few questions asking if anyone had similar issues, and got directly in touch with about 20 people who responded to involve them in customer research, then kept in touch with them as I was developing the product for feedback. Those 20 by word of mouth led to a bunch more people trying it out. It's difficult to put a specific number on whether that was 100 or a bit more or fewer, but a few cycles of word of mouth from happy users got me over the 100 users easily.

Inspiring, you must be having a good number of connections on LinkedIn. Target audience?

I just checked, and have about 9K connections on LinkedIn. I assume with the ability to pay for post promotion you could get a similar reach by paying linkedin a few bucks.

This was for a tool to speed up making educational videos, so I tried to reach out to people who were doing online courses and educational materials.