I'm distributing my software through Chrome Web Store which is free. Other services where I am on a free tier: Airtable for CRM etc, Netlify for web hosting. For marketing/sales I've used LinkedIn's Sales Navigator for a couple of months; this is a paid service that costs about $100 per month.
Twitter is great for networking. I also get a lot of value from communities on Slack and Discord for my niche. Curious what platforms others are finding most useful?