The strangler pattern
Replacing a legacy system incrementally. New capability grows around the old system and traffic is routed away piece by piece, until the old system can be retired. It is the standing alternative to the big-bang rewrite, and the reason a manager can insist that the incremental path is explored first.
Evidence grade: practice A widely adopted practitioner model with clear provenance.
Use it when
Any proposal to rewrite a working system from scratch.
Where it stops working
It takes longer to reach a clean end state, and it needs interfaces in the old system to strangle at, which some systems lack.
Where the standard uses it
- TJ-1Evaluating architectural decisions and their organisational consequencesTrade-offs, reversibility, and who has to coordinate because of this.
Sources
- Martin Fowler. StranglerFigApplication. martinfowler.com, 2004. In the bibliography
Used alongside it
- Architecture review forums practice
- Conway's law practice
- One-way and two-way doors practice
- The mirroring hypothesis research
Cite this model
Chicago, BibTeX and licence →Engineering Management Academy. (2026). The strangler pattern. In Engineering Management Academy Body of Knowledge (Version 3.1, TEC.strangler-pattern). https://www.engineeringmanagement.academy/body-of-knowledge/techniques/strangler-pattern