Expressions and Variables

n8n expressions insert dynamic values into node parameters using double curly braces {{ }}. Anything inside the braces is evaluated as JavaScript at runtime and replaced with the result. Expressions read data from the current item with $json, from specific upstream nodes with $('Node Name'), and from built-in variables such as $now and $execution.id, so nodes react to data instead of using fixed values.

What is n8n expression syntax?

n8n uses double curly braces {{ }} to embed expressions in node parameters. Anything inside the braces is evaluated as JavaScript at runtime and replaced with the result.

{{ $json.firstName + ' ' + $json.lastName }}

Toggle a parameter field to Expression mode (the = icon) before entering an expression.

How do you access data from previous nodes?

Current Item

Variable	Description
$json	The json property of the current item from the immediately preceding node
$binary	The binary property of the current item (file data)
$input.item.json	Same as $json (explicit form)

{{ $json.email }}
{{ $json.address.city }}
{{ $json.tags[0] }}

Specific Upstream Node

Reference a node by name to access its output:

{{ $('Customer Lookup').item.json.name }}
{{ $('HTTP Request').first().json.id }}
{{ $('HTTP Request').all() }}

All Items

Method	Returns
$input.all()	Array of all items from the immediate parent
$input.first()	The first item from the immediate parent
$('Node Name').all()	All items from a named node

What built-in variables are available?

Variable	Description
$now	Current date/time as a Luxon DateTime object
$today	Current date at midnight as a Luxon DateTime
$workflow.id	ID of the current workflow
$workflow.name	Name of the current workflow
$workflow.active	Whether the workflow is active (true/false)
$execution.id	ID of the current execution
$execution.mode	manual or production
$execution.resumeUrl	URL to resume a waiting execution
$runIndex	How many times the current node has run in this execution (useful in loops)
$itemIndex	Index of the current item in the input array
$position	Same as $itemIndex

How do you use JavaScript in expressions?

Full JavaScript is available inside {{ }}. Common patterns:

{{ $json.price * 1.1 }}

{{ $json.status === 'active' ? 'Yes' : 'No' }}

{{ $json.tags.join(', ') }}

{{ new Date($json.timestamp).toISOString() }}

{{ $now.minus({ days: 7 }).toISO() }}

Warning

Expressions must be single-line evaluations that return a value. For multi-line logic, use the Code node instead.

What are common expression patterns?

Default value when field is missing:

{{ $json.nickname ?? $json.firstName ?? 'Unknown' }}

Format a date:

{{ $now.toFormat('yyyy-MM-dd') }}

Build a dynamic URL:

{{ 'https://api.example.com/users/' + $json.userId }}

Tip

Use the Expression Editor (click the field, then the expression tab) to get autocomplete suggestions and preview results against real execution data.

Related tips: Data Transformation, Code Node Mastery

What should you read next?

• Connections & Data Flow
• Code Node Reference
• Edit Fields Node Reference
• Data Transformation Tips
• Code Node Mastery