Child flow

A child flow in Power Automate is a flow invoked by another flow, enabling decomposition of complex workflows into reusable, maintainable units. Child flows are triggered by Power Apps or HTTP request triggers; parents call them via HTTP action with JSON payload matching the child's input schema. Common patterns: shared authentication helpers, document-generation services, audit-logging services, notification orchestrators that handle multi-channel delivery. Benefits include reusability (one child flow used by many parents), maintainability (smaller flows are easier to understand and modify), and independent versioning. Each invocation has HTTP overhead, so child flows suit substantial logic rather than trivial helper code.

In practice, child flows solve the same problem a function or a shared library solves in traditional programming: instead of copying the same five-step "send this notification through email or Teams depending on the user's preference" logic into every parent flow that needs it, one child flow implements it once and every parent calls it. Changing the notification logic later means editing one child flow, not hunting down and re-editing every parent flow that duplicated it.

Where confusion shows up: a child flow's failure doesn't always surface clearly in the parent's run history by default — a parent that calls a child via HTTP action needs its own error handling (checking the response status, configuring run-after) to actually notice and react to a child flow failure, rather than assuming the parent will automatically stop or alert on a child's error. Overusing child flows for genuinely trivial logic is also a common overcorrection: the HTTP call overhead and the extra layer of indirection cost more than they save when the "shared" logic is two lines long and used in only one place.