Core Nodes and the UI
The most-used trigger and action nodes in n8n. Node data (items), parameters, and execution modes.
In this chapter
The n8n UI is a single canvas with drag-and-drop nodes. Every workflow starts with a trigger, then chains action nodes. In this chapter you will learn the nodes you will use most (Manual, Schedule, Webhook, Set, Code) and how data moves between nodes (items, $json, $input).
Topics
- Trigger nodes: Manual, Schedule, Webhook
- Set, Edit Fields, Code nodes
- Function vs Function Item: when to use which
- Items, $json and $input
- Test vs Production execution modes
- How to debug a red node
Trigger nodes: Manual, Schedule, Webhook
Every workflow begins with a trigger. Manual Trigger: started with the 'Execute Workflow' button — ideal for development and testing. Schedule Trigger: fires on a cron-like schedule (e.g. every night at 02:00). Webhook Trigger: fires the moment an external POST/GET request arrives — the heart of integrations. Pick the right trigger for the scenario.
Set, Edit Fields and Code nodes
Set (now called Edit Fields): transforms data, adds new fields, renames keys. Code: lets you write JavaScript for complex transforms, loops and custom logic. Rule of thumb: if the rule fits in an expression, Set is enough; if it really needs code, move to Code.
Function vs Function Item
The Code node (formerly Function/Function Item) runs in two modes. 'Run Once for All Items' processes everything in one go (same as Function mode). 'Run Once for Each Item' runs per item (Function Item). Bulk operations are faster with the first mode; item-by-item transforms read cleaner with the second.
Items: $json, $input and $node
n8n passes the output of each node to the next as an array of 'items'. Each item is a { json: {...}, binary: {...} } object. In the next node, expressions reach the data: $json.field is the current item's field, $input.first().json.field is the first item's field, $node['NodeName'].json.field reads another node's output. Internalising these three covers 80% of working with n8n.
Test vs Production execution
n8n has two execution modes. Test (Editor): manual test, each node can run individually, results land in a table. Production (Active): when the workflow is set Active, triggers run in real time and results are logged in Executions. Always validate in Test, then make it Active.
How to debug a red node
A red node means an error. Click it and read the message in the Output tab. The most common causes: a bad expression (not inside {{ }}), missing credentials, a 4xx/5xx from an API, or a missing expected field. Use 'Pin Data' to lock in a previous output and re-run the workflow against the same input as often as you like.
This chapter's workflow (n8n editor view)