A workflow is a visual program made of blocks. It's where you compose everything else in Sim, data, operations, integrations, and AI agents, into a process, and bind it to a trigger so it runs.
What you will learn
Read a workflow
Blocks are steps, some blocks are triggers, and connections wire them into an order that runs.
Follow the data
Each block has parameters and produces an output. A later block reads an earlier output with a connection tag.
See how it executes
Independent blocks run at once; a block waits only for what it depends on. Every run is recorded in the logs.
The pieces
- A workflow is a visual program, you build it by placing and wiring blocks, not by writing a script.
- It's made of blocks, each one a step. Some blocks are triggers: they decide what starts the run and what it receives.
- Connections link blocks together. They set the order: a block runs after the blocks wired into it finish.
- Blocks have parameters that configure how they work. A Fetch Webpage block takes a URL; an Agent block takes a model and a prompt.
- When a workflow runs, Sim records what each block produced. Any later block can read an earlier block's output through a connection tag, like
<fetch.content>. - Everything that happened is saved in the logs, the trigger, every block, and each block's input and output, so you can see exactly where a value came from.
Here's a small workflow you can read top to bottom, blocks wired in order, each one a step. The highlighted block reads an earlier block's output through a connection tag:
How execution flows
A block waits only for the blocks it depends on, nothing else.
So if A feeds both B and C, then B and C start at the same moment A finishes; they don't wait for each other. And if B and C both feed D, then D waits for both before it runs. The shape of the connections is the execution plan.
Branches, loops, and parallel
From those primitives you get expressive control flow: branch down one path or another with a Condition or Router, loop over a list, run work in parallel across many items. These are the expressive core of what you'll build, and they're all just blocks and connections.