Endpoint Decay Curve

Endpoint Decay Curve is the idea that every API an agency ships starts depreciating the moment it goes live, and the rate of decay is set at design time, not at handoff. An endpoint with a written contract, a versioning policy, and a live reference decays slowly; one shipped as a quick fix for a client deadline decays fast, and the cost lands on the agency as unpaid maintenance. The curve matters because agencies price delivery as a project but absorb decay as a retainer, so undocumented endpoints quietly convert margin into support hours. A concrete example: a client CRM integration built without a spec will break on the vendor's next schema change, and the agency eats the debugging call. Documentation platforms such as ReadMe and design-first tooling like Apidog exist precisely to flatten this curve, while gateway layers such as Zuplo or API7 can absorb breaking changes through versioning and rate rules rather than emergency patches.