Set Variable

The set variable step stores key-value pairs in the $vars namespace, which persists across the entire workflow execution. The step editor shows a key-value form where you define variable names and their values.

How It Works

Each set-variable step merges its output into the existing $vars — it doesn’t replace them. This means values accumulate and you can update individual keys without losing others.

First set-variable step — initialize some state:

Key	Value
offset	0
hasMore	true
items	{{ $util.emptyArray }}

Later set-variable step — update specific keys (the others are preserved):

Key	Value
offset	100
items	{{ $vars.items | arrayConcat: fetch-page.body.data }}

After this, $vars contains { offset: 100, hasMore: true, items: [...] }.

Referencing Earlier Keys in the Same Step

Variables in a single set-variable step are resolved top-to-bottom, so any key can reference a key defined above it in the same step via {{ $vars.key }}. This lets you derive several related values from a single base without spreading them across multiple steps.

Compose related URLs from a single base:

Key	Value
apiBase	https://api.example.com/{{ $env.STAGE }}
searchUrl	{{ $vars.apiBase }}/search
usersUrl	{{ $vars.apiBase }}/users
ordersUrl	{{ $vars.apiBase }}/orders

After this single step, $vars.apiBase, $vars.searchUrl, $vars.usersUrl, and $vars.ordersUrl are all set — and changing the stage in one place updates them all.

Snapshot a timestamp once and derive a filename from it:

Key	Value
runStartedAt	{{ $util.now }}
today	{{ $vars.runStartedAt | date: "%Y-%m-%d" }}
reportFilename	report_{{ $vars.today }}.csv

Capturing runStartedAt once and reusing it guarantees every derived value is based on the same instant — no risk of $util.now returning a slightly different timestamp on each reference.

Accumulate into an array:

Key	Value
tags	{{ $util.emptyArray }}
allTags	{{ $vars.tags | push: initial.category | push: "automated" }}

Because resolution is sequential within the step, $vars.tags is [] by the time allTags is computed, so allTags becomes [<category>, "automated"].

Note

Top-to-bottom resolution only applies to keys within the same step. Across steps, the merge order is what matters: a later set-variable step always sees the latest value of $vars from previous steps.

Common Patterns

Accumulating inside a for-each loop:

Key	Value
processedCount	{{ $vars.processedCount | plus: 1 }}

Storing computed values for later steps:

Key	Value
fullName	{{ initial.firstName }} {{ initial.lastName }}
isVip	{{ initial.totalOrders | gte: 100 }}

Access variables anywhere in the workflow:

{{ $vars.processedCount }}
{{ $vars.fullName }}