Turns a Notion workspace into a professional, SEO-optimized public knowledge base / help center / product-docs site: customers keep writing content in Notion, HelpKit renders it as a fast, custom-domain, full-text-searchable site with an embeddable web/mobile widget, gated/password access, analytics, and an optional AI chatbot add-on. Solo founder Dominik Sobe (Austria, self-taught developer), bootstrapped, 'run by a human' (Seven Degrees Labs LLC). Publicly documented multi-year growth via Indie Hackers/YouTube/blog milestone posts: ~$1k MRR (2021) -> $3k MRR / 130 paying customers (June 2022) -> $5k MRR (~2022) -> $10k+ MRR (per a July 2025 case study), now 1,000+ customers and a 5-star G2 rating -- sustained, verifiable growth over ~5 years, not a one-off milestone claim. Pricing starts around $19/month, with a $49/month AI chatbot add-on. Fits criteria: no network effects (each customer's help center is standalone); narrow, simple feature set (fetch content via the Notion API, render as fast cached pages, custom domain/SSL, full-text search, embeddable JS widget) realistically scopeable for a solo 3-6 month Rust build (axum/tokio backend + a search index); listed on SaaSHub and G2 with its own dedicated alternatives page in a comparison-site category (vs. Document360, GitBook, Mintlify, HelpDocs) that's thinner than more commoditized niches; not a regulated space; no on-call/uptime-SLA burden beyond normal web hosting. Self-hosting is a genuine gap -- HelpKit is hosted-only today, so a self-hosted/Docker version (still pulling live from the customer's own Notion workspace) would appeal to privacy-conscious or cost-sensitive teams.