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Custom & Marketplace Actions

The blocks built into FlowRunner cover a lot, but no built-in set covers everything. When the step you need does not exist, you do not have to fall back to hand-built API calls for the rest of the flow's life - you can add to the blocks available to you. Check what is already there first, then work down the ways to add something, because the first that fits is nearly always the least work.

First, check what already exists

A large library of Extensions ships with FlowRunner - blocks for outside services like Acumatica, Airtable, Apollo, Asana, Slack, Stripe, and many more - with nothing to install. Beyond those, a Marketplace offers pre-built actions you can install into your workspace. Before building anything, check whether the capability you need is already covered. See Blocks.

Add a service's tools with an MCP server

If the service publishes tools through the Model Context Protocol, registering its server once brings its whole catalog in. Those tools then appear as blocks you drop into a flow, and they are simultaneously available to your AI Agent blocks as tools an agent can call on its own. Nothing to build, nothing to host.

This is often the fastest route to a capability that has no built-in block. See MCP Servers.

Turn your own flows into blocks

Work you have already built as a flow appears as a block under Flows as Actions, ready to place in other flows, so a routine becomes a reusable step without writing anything new. This is the cheapest kind of extension because you get it the moment the flow exists. See Running Another Flow.

Build your own action

When nothing above fits - a proprietary system, a piece of logic that has to run as one unit - you can package your own block. For a one-off piece of code inside a single flow, a Custom Cloud Code block runs what you write without packaging anything at all.