> ## Documentation Index
> Fetch the complete documentation index at: https://docs.qxlabs.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Custom code
The **Custom Code** node runs Python inside a flow, for the steps no built-in node covers. It sits in the **Workflow Basics** category.
The AI builder can handle this node for you. Describe what the step should do in **Chat** mode, and it writes the code, sets up its inputs and outputs, and tests it before adding it to your flow. See [Build with AI](/flows/build-with-ai).
## How it works
The code lives in the **Code** field, written as a `process` function that receives the node's inputs and returns its outputs.
The ports on the node come from what is declared. Each row under **Declared Inputs** becomes a field you can wire an earlier node into, and each row under **Declared Outputs** becomes a value later nodes can use. Every row has a name and a type.
Two more settings matter when the code does something heavier. **Pip Packages** installs any Python libraries it needs, and **Timeout (seconds)** caps how long it may run before the flow gives up on it.
If you do edit the code by hand, it must return a value for every declared output, and nothing is kept between runs, so treat each run as a fresh start.