I Built a £500/mo Side Project Using Only Free AI Tools (Here's What Actually Worked)

Six months ago I built a SaaS tool using only free AI tools. No paid APIs, no expensive infrastructure. Here's what I learned about what actually works. The Project An LLM monitoring tool. Drift detection, cost tracking, alerting. The stack: Frontend : GitHub Pages (free) Backend : Cloudflare Workers (free tier) Database : Supabase (free tier) LLM calls : Free tier allocations from OpenAI, Anthropic, Google Monitoring : Self-hosted on a £10/month VPS Total monthly cost: £10 for the VPS. Everything else: free. What Actually Worked 1. GitHub Pages for Static Sites Perfect for landing pages, documentation, simple dashboards. Zero cost, zero maintenance. 2. Cloudflare Workers for API Routes Generous free tier (100k requests/day). Fast. Easy to deploy. Good for lightweight API work. 3. Supabase Free Tier 50k monthly active users. 5GB database. 1GB file storage. Enough for a small SaaS. 4. Free LLM Tier OpenAI: $5 free credits that last months for light use. Anthropic: Free tier with claude-