• No one but you will build the services you need in time for you to use them
  • If you build a service that no one else asked for, you will have built it for yourself
  • If you build a service for yourself,  you will optimize it for your own use
    • It is therefore the optimal service for you to use
    • It is very unlikely to be the optimal one for anyone else to use
    • No one besides you will use it
    • You will not use anyone else’s


Therefore, any team building reusable services must build each one only after two or more people have asked for it, with full knowledge that the resulting service will almost certainly be available too late for any of them to use it.

Therefore, no team should intentionally build reusable services.

Additional Laws and Corollaries

  • If you invest in improving someone else’s pre-existing service, you will create a reusable service.
  • Creating a reusable service, be improving someone else’s service, will cost you more, up front, than writing a completely new one.
  • The cost of maintaining a service increases proportionally to the number of consumers that use it.