What is the Strangler Fig Pattern?

An architectural pattern for incrementally migrating a legacy system (monolith) to a new architecture (microservices).

Instead of a risky 'big bang' rewrite, you place an intermediary routing layer (Facade/Gateway) in front of the legacy system. You gradually build new microservices to replace legacy functionality. The router redirects requests to the new service while keeping unmigrated requests pointed to the monolith.