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-3-haiku.
Google: Gemini API free tier.
What Did Not Work
1. Heavy LLM Usage
Free tiers run out fast. For anything production, you need paid API access.
2. Complex Database Queries
Supabase free tier has limitations. Performance degrades with complex joins.
3. File Processing
Image processing, PDF generation, anything CPU-heavy: not suitable for free tiers.
The Honest Numbers
| Month | Revenue | Costs | Profit |
|---|---|---|---|
| Month 1 | £0 | £10 | -£10 |
| Month 2 | £0 | £10 | -£10 |
| Month 3 | £29 | £10 | £19 |
| Month 4 | £58 | £10 | £48 |
| Month 5 | £87 | £10 | £77 |
| Month 6 | £145 | £10 | £135 |
Started charging in month 3. Now profitable.
What I Would Do Differently
- Start charging earlier — month 1, not month 3
- Use paid LLM APIs from day 1 — the free tiers are limiting
- Track everything — I wish I had monitoring from day 1
The lesson: free tiers are great for prototyping. Not for production.
If you are building AI tools, start with the free tiers to validate. Switch to paid when you have revenue. That's what I did.
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