Dynamic variables

Dynamic variables generate realistic test data at run time. Write {{$name}} anywhere a regular variable works — URLs, headers, bodies — and the runner fills in a generated value. There are 69 built-ins covering identifiers, time, identity, contact, address, finance, internet, commerce, text, and primitive values.

Syntax

Dynamic variables use the same {{double_brace}} syntax as other variables, with a $ prefix:

{
  "idempotency_key": "{{$uuid}}",
  "customer": {
    "name": "{{$fullName}}",
    "email": "{{$email}}"
  },
  "card_number": "{{$creditCard}}",
  "created_at": "{{$timestamp}}"
}

Common variables

Variable	Generates	Example output
`{{$uuid}}`	A UUIDv4	`9f2c1a4e-7b3d-4f08-a1c5-2e9d8b6f0a31`
`{{$timestamp}}`	Unix seconds at execution start	`1765290061`
`{{$isoTimestamp}}`	RFC 3339 timestamp at execution start	`2026-06-09T14:21:01Z`
`{{$today}}`	Execution date as YYYY-MM-DD	`2026-06-09`
`{{$email}}`	An email address	`dane.streich@example.org`
`{{$fullName}}`	A full name	`Dane Streich`
`{{$firstName}}`	A first name	`Dane`
`{{$creditCard}}`	A card number	`4716 3915 0461 8344`
`{{$ipv4}}`	An IPv4 address	`192.0.2.146`
`{{$price}}`	A price	`42.90`
`{{$company}}`	A company name	`Streich Group`
`{{$int}}`	An integer	`7301`

The remaining built-ins follow the same pattern — names like {{$lastName}}, {{$phone}}, {{$city}}, {{$country}}, {{$url}}, {{$domain}}, {{$userAgent}}, {{$word}}, {{$bool}} — all faker-backed.

Deterministic per execution

Values are seeded from the execution ID. Within one run, the generator sequence is consistent — and time-based variables like {{$timestamp}}, {{$isoTimestamp}}, and {{$today}} are stable for the whole execution, so every node that references them sees the same value. A new execution gets a fresh seed and fresh data.

This keeps runs debuggable: when you read a node result in run history, the generated values you see are the ones that were actually sent.

Dynamic variables vs environment variables

	Dynamic variables	Environment variables
Purpose	Generated test data — fresh per run	Configuration — stable per environment
Examples	`{{$uuid}}`, `{{$email}}`, `{{$creditCard}}`	`{{BASE_URL}}`, `{{API_TOKEN}}`
Defined by	Built in, nothing to configure	You, at the org or flow level
Changes when	Every execution	You change them, or pick a different environment at launch

Use a dynamic variable when each run should send unique data — a fresh idempotency key, a new test customer. Use an environment variable when the value depends on where you run — the staging base URL, an API token.

Next steps

Environments & variables — org defaults, overlays, and flow-level variables
Building flows — where variables fit into nodes and requests
Outputs & assertions — pass real response values between nodes