Combinant® Design

A software design method for decreasing the cost of change. Because software shouldn't scream every time you change it. For teams building long-lived systems.

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Next Event — Free Explore Courses

What Combinant® Design Does

Combination over IFs. Recombinable software pieces. Decreasing cost of change.

Why does adding features always cost more, never less? How do you make the cost of change go down?

Combinant® Design builds small pieces and evolves them across products and domains into pieces with higher recombinability — like making multiple recipes from the same ingredients. Over time, the cost of the next feature and the next product lowers — because instead of developing new pieces, you recombine already existing ones.

The Decreasing Cost Challenge

Build once. Recombine across domains. Measure the cost going down.

Three products. Three different domains. One codebase.

Each course builds on the previous one: same codebase, new product. We apply Combinant® Design principles and measure the effort at every step. Does the cost of change actually go down? By the third product, you can see it in the data.

Combining Breakout

The starting point
A complete Breakout game built by combination. Collisions without IF. New features at decreasing cost. Then we recombine the same pieces into new games. We measure it all. Learn More

Combining MiniVi

Same pieces, different domain
Building blocks from Breakout, applied to a text editor. A completely different domain. How many pieces carry over? How many new ones are needed? Did the effort decrease? Learn More

Combining Trading Alerts

The curve continues
A trading alert engine built from the same codebase. How much can we recombine? How much new work is needed? By the third product, the cost curve tells the full story. Learn More

Next Events

The Breakout Game: Six Designs Compared

Tuesday, June 16, 2026 — 4 PM (UTC+4)
Free /2.5 hours

Francesco Cirillo shows the same Breakout game five different ways. What works, what breaks, what happens when a requirement changes. Learn More.

  • 2.5 hours including Q&A
  • OOP, procedural, structured, event-driven, functional — side by side
  • IF count and cost of change compared across all five
  • Is there a better way? Join the Combining Breakout course
Register — Free

Behind Combinant® Design

Francesco Cirillo

30+ Years in Software Design • Creator of the Pomodoro® Technique

Began programming in the early 1980s, primarily on the Apple ][.

Economics degree in Rome. Thesis on economies of scale and scope in banking — why producing more, and in different contexts, can cost less over time. The same question came back years later: why does software so often become more expensive to change instead of less?

Object mentor for Sun Microsystems. First continental European at the XP Immersion, 1999. Selected by Kent Beck to bring XP to Europe. Founded XPLabs in 2000 — the first company fully dedicated to developing, teaching, and mentoring eXtreme Programming. Editor, second edition of Extreme Programming Explained. Creator of the Anti-IF Campaign. Creator of the Pomodoro® Technique.

Created RRP and Combinant® Design in 2008. Full story coming soon.

Combine software. Reduce the cost of change.