📌 Understanding ServiceNow Flow Designer: Triggers, Actions, Subflows & Custom Actions

ServiceNow Flow Designer is one of the most powerful no-code/low-code automation tools available on the platform. It enables process automation across applications without writing complex scripts, while still offering the flexibility to incorporate server-side logic when needed.

In this article, we will explore the core building blocks of Flow Designer — Flows, Triggers, Actions, Subflows, and Custom Actions, along with real-time examples to help you understand how they are used in automation.

🔷 What is Flow Designer in ServiceNow?

Flow Designer is a Now Platform feature that allows developers and process owners to automate business processes using a visual, drag-and-drop interface.

It replaces older workflow models and provides a modern, scalable approach to orchestration and automation.

Key benefits of Flow Designer

No-code/low-code automation
Reusability through subflows and actions
Easy integration with other systems using spokes
Faster development and better maintainability
Supports delegation of logic to process owners, not just developers

Flow Designer helps both technical and non-technical users automate processes like incident management, approvals, notifications, catalog fulfillment, HR tasks, and more.

🔷 What is a Trigger in Flow Designer?

A trigger defines when the flow should run.

It is the starting point of every Flow Designer automation.

Types of triggers

Record Trigger
Runs when a record is created, updated, or deleted.
Example: Run a flow when an Incident is created.
Service Catalog Trigger
Runs when a specific catalog item is submitted.
Example: Fulfill a laptop request automatically.
Application Trigger
Some integrations/spokes introduce custom triggers.
Schedule Trigger
Allows flows to run periodically (hourly, daily, weekly).
Example: Auto-close stale incidents daily.

Real-time example

A flow is triggered whenever a new Incident is created with priority P1.

🔷 What are Actions in Flow Designer?

An Action is a single step executed within a flow.

Actions can:

Update or create records
Send emails or notifications
Run scripts
Integrate with external systems
Perform lookups, assignments, transformations

ServiceNow provides many out-of-the-box actions through:

Core Actions
Spokes
IntegrationHub connectors

Example actions

Create Record
Lookup User
Update Incident
Send Email
Generate Task
REST Step (to call external APIs)

Actions are the heart of automation logic.

🔷 What is a Subflow in ServiceNow?

A Subflow is a reusable flow that can be called from other flows.

You can think of it as a function in programming — reusable, modular, and maintainable.

When do we use Subflows?

When the same logic needs to be used across multiple flows
To avoid duplicating steps
To separate complex logic into smaller parts
To maintain clean and modular automation

Real-world example

A “Manager Approval Subflow” used by multiple catalog items.

Instead of recreating the approval logic for 10 catalog items, you just reuse the subflow.

🔷 What are Custom Actions in ServiceNow Flow Designer?

Custom Actions allow developers to build their own reusable action steps.

They package:

Inputs
Outputs
Flow logic
Scripts
Conditions

…into a single reusable unit.

They are ideal for automation that needs consistent behavior across flows.

Why do we need Custom Actions?

To encapsulate complex server-side logic
To avoid rewriting scripts in multiple flows
To standardize business rules
To make flows simpler for non-technical users
To reuse common automation patterns

Real-time example

A custom action that:

Determines assignment group based on Incident category
Returns the group as an output
Is used in multiple flows (Incident, Problem, Request)

This avoids writing the same logic again and again.

If you also want to take a look on video explaining about flow designer and it's component, then follow the below playlist👇

https://youtube.com/playlist?list=PL2cOC9C3HI-wLGsTeknhlZe3yYInfDzqs&si=UwlkDAAB8PfA-6TJ

Mark this article helpful, if it gives you the basic understanding on flow designer.

Regards,

Abhishek Thakur