Parallel block

Configure the Parallel block to run independent branches at the same time and collect their results for the steps that come after it.

The Parallel block (type: "parallel") runs several branches at the same time and waits for them before the run moves on. A branch is either a fixed list of steps or a copy of a step template made for each item in a list. For the plain-language guide, see Repeat for each item or run steps side by side.

When to use it

Pull balances from two or more systems at once before a reconciliation step.
Look up a customer in the CRM and in the ledger at the same time.
Fan out one independent call per item, such as fetching each invoice PDF, when order does not matter.

When each item depends on the one before, or must run one at a time, use the Loop block.

Configuration

Set exactly one of branches or forEach.

Field (`config` key)	Editor label	Type	Required	Meaning
`branches`	The paths you draw from the block	array	One of `branches` or `forEach`	Fixed branches. Each is `{ "id", "name", "steps": [step ids] }`. Branch names must be unique.
`forEach`	ForEach Source and ForEach Binding	object	One of `branches` or `forEach`	`{ "source", "as", "stepTemplate" }`. See below.
`strategy`	Strategy	`wait-all` or `fail-fast`	No	Default `wait-all`. See Errors and limits.
`maxConcurrency`	Max Concurrency	number	No	1 to 100 in the definition; the editor slider covers 1 to 20 and defaults to 5. When unset, all branches start together.
`timeoutMs`	Timeout (ms)	number	No	At least 1000. Time allowed for each branch.

`forEach` branches

Key	Meaning
`source`	A template reference that resolves to a list, such as `{{steps.list_entities.items}}`.
`as`	The binding name. Default `item`.
`stepTemplate`	One or more full step definitions, copied once per item.

Before each copy runs, the exact text {{item}} in its name, action and config is replaced with the item (objects become JSON text), and {{itemIndex}} with its 0-based position. With as: "entity", use {{entity}} and {{entityIndex}}. Paths such as {{item.id}} are not replaced, and forEach copies do not use the variables root. Each copy's step id is the template id followed by __<index>, for example fetch_balance__0.

In the editor, a Parallel block that you draw becomes fixed branches. A forEach Parallel keeps its step template when you edit it in the editor, but the template itself is authored in the workflow definition.

Output

Field	Type	Meaning
`branches`	object	Results keyed by branch id. Each has `branchId`, `branchName`, `success`, `output` (from the branch's last step), `error`, `durationMs` and `stepResults`.
`branchesByName`	object	The same results keyed by branch name.
`allSucceeded`	boolean	`true` when no branch failed.
`failedBranches`	string array	Ids of failed branches.
`durationMs`	number	Time the parallel step took.

Read one branch's output as {{steps.<step id>.branchesByName.<branch name>.output}}, or a step inside a branch directly as {{steps.<inner step id>.<path>}}.

The editor's output list shows results, errors and completedCount; the executor returns the fields above.

Example

This workflow reads the Stripe balance and the QuickBooks balance sheet at the same time, then compares them in a Code step.

{
  "name": "Cash position snapshot",
  "trigger": { "type": "api" },
  "steps": [
    {
      "id": "fetch_both",
      "type": "parallel",
      "name": "Fetch balances",
      "config": {
        "branches": [
          { "id": "stripe", "name": "Stripe", "steps": ["stripe_balance"] },
          { "id": "ledger", "name": "Ledger", "steps": ["qb_balance_sheet"] }
        ],
        "strategy": "fail-fast",
        "timeoutMs": 60000
      }
    },
    {
      "id": "stripe_balance",
      "type": "action",
      "name": "Get Stripe balance",
      "action": "stripe.getBalance",
      "config": {}
    },
    {
      "id": "qb_balance_sheet",
      "type": "action",
      "name": "Run balance sheet",
      "action": "quickbooks.runReport",
      "config": { "reportType": "BalanceSheet" }
    },
    {
      "id": "compare",
      "type": "code",
      "name": "Compare balances",
      "config": {
        "input": {
          "stripe": "{{steps.stripe_balance}}",
          "ledger": "{{steps.qb_balance_sheet}}"
        },
        "code": "return { stripeAvailable: input.stripe.available, ledgerReport: input.ledger.Header };"
      }
    }
  ]
}

stripe_balance and qb_balance_sheet appear in the top-level steps array but run only from their branch.

Errors and limits

A config with both or neither of branches and forEach, or with duplicate branch names, is refused when the workflow is saved.
wait-all: each branch runs to the end. If any branch failed, the parallel step is recorded as failed and the run carries on.
fail-fast: the run fails with Parallel execution failed when a branch fails.
A branch that runs past timeoutMs fails.
A forEach source that does not resolve to a list fails the step. An empty list completes with no branches.