A couple weeks ago I launched an AI generator of fairy tales for children in Ukrainian. It makes parents' evenings easier - now they don't have to come up with fairy tales, but can generate them. Thanks to this, the news about the appearance of our product went viral, and for these 2 weeks we received 2000+ registrations in the service for free (we didn't spend a penny on advertising). Exclusively thanks to the posts in Linkedin and Facebook about the introduction of the service, then this news was picked up by the media and Telegram channels.
You use cold outreach on LinkedIn and Email. Other then that, go into communities that are relevant to your product and engage there, you can also again use cold outreach for them :D
To acquire your first 100 users without paid ads, focus on these strategies:
Leverage social media: Create engaging content and share it across platforms.
Network and collaborate: Partner with influencers or complementary businesses.
Content marketing: Develop valuable blog posts, videos, or podcasts.
SEO: Optimize your website for search engines.
Referrals: Encourage satisfied users to refer others.
Online communities: Participate and share insights in relevant forums.
Email marketing: Build an email list and share updates.