A founder told me they were paying $800/month for a CRM. When I asked how much of it they actually used, they paused — then said maybe 10%.
That number stuck with me.
Because it's not an edge case. It's the norm. And it led me to a question I couldn't stop thinking about:
What if you just built the 10%?
That question turned into a challenge I'm calling Rebuild the Stack — where I take massive SaaS products like HubSpot, Ahrefs, and Intercom, strip them down to their actual core value, and rebuild lean, API-first versions built for developers and AI agents.
The Real Problem with Modern SaaS
Every powerful SaaS tool ships with the same assumptions baked in:
- A human is in the driver's seat
- That human wants a polished dashboard
- That human is willing to sit through onboarding flows
- That human will eventually upgrade to unlock the features they actually need
Those assumptions made sense in 2012. They're increasingly wrong in 2025.
Developers building products don't need the dashboard. Teams deploying AI agents don't need the onboarding flow. What they need is the primitive — the core capability, cleanly exposed via API, documented well enough that an agent can consume it without handholding.
"The most valuable part of most SaaS products isn't the product. It's the underlying capability wrapped inside it."
What Rebuild the Stack Actually Is
Each episode of this challenge follows the same structure:
| Phase | What Happens |
|---|---|
| Deconstruct | Break down a well-known SaaS product feature by feature |
| Identify | Extract the 1–3 features that deliver 90% of the value |
| Rebuild | Ship a lean, documented, API-first version of those features |
| Optimise | Tune the interface for developer and AI agent consumption |
No bloat. No pricing tiers gating core functionality. No UI required to get value.
Why API-First?
The shift happening in software right now is subtle but significant. AI agents are becoming first-class consumers of SaaS functionality. And agents don't care about your onboarding flow — they care about:
- Predictable inputs and outputs
- Clear error handling
- Minimal authentication friction
- Well-structured documentation
Building API-first isn't just a developer preference. It's increasingly the only architecture that works for both humans and the agents they're deploying alongside them.
What I'll Share Along the Way
This isn't just a build log. Every episode will include the full architecture reasoning — what I built, what I cut, and why. That means:
- The deconstruction — how I identified the core value in each product
- The tradeoffs — what I deliberately left out and the cost of that decision
- The architecture — schema design, API structure, and infrastructure choices
- The mistakes — what broke, what I'd do differently, and what surprised me
Software is full of people sharing finished work. I'm more interested in sharing the decisions made along the way.
The First Build
The first product drops soon. It targets one of the most over-engineered categories in SaaS — and the rebuild fits in under 500 lines of backend code.
If you've ever paid for a tool and used a fraction of it, this challenge is for you.
Which SaaS product has frustrated you most? Drop it in the comments — it might just be Episode 2.