Using FlowMattic Variables to Generate Random Numbers

FlowMattic includes a powerful built-in variable system, accessible from a dedicated admin page called “Variables”. This page not only lists pre-defined system variables like random_number:<NUMBER>, but also allows users to create their own custom variables for reuse across workflows.

One of the most useful built-in variables is the random number generator, which helps you generate a dynamic number between 0 and your defined upper limit — perfect for things like OTPs, invoice IDs, or test data.

🔧 How It Works

To generate a random number, you use the following syntax:

{{random_number:<NUMBER>}}

• random_number: is the variable type.
• <NUMBER> defines the upper limit.
• It generates a random number between 0 and <NUMBER> (inclusive of 0, exclusive of ).

✅ Example:

{{random_number:100}}

Will generate a number like 72 (any number between 0 and 100).

🪜 Step-by-Step: How to Use Random Number Variable

1. Open your workflow in FlowMattic.
2. Add or select a step where you want to use a dynamic random number.
3. Inside the input field, click the + icon to open the Dynamic Fields popup.
4. The first section in the popup is FlowMattic Variables — search or scroll to find random_number:<NUMBER>.
5. Select or modify the number to suit your range, e.g., random_number:1000 for values between 0 and 1000.
6. Insert the variable — it will appear as {{random_number:1000}}.
7. You can now use this variable directly — for example, in number formatting, API calls, or creating dynamic content.

📦 Use Case Examples

1. 🔐 Generate 4-digit OTP

{{random_number:9999}}

• Used to create a random 4-digit One-Time Password.
• Example Output: 4832

2. 📦 Create a unique invoice suffix

INV-{{random_number:100000}}

• Used to create invoice codes like INV-49832.

3. 🧪 Add a random delay in testing flows

{{random_number:10}}

• Used to randomly set wait times between 0 to 10 seconds for testing.

4. 🎟 Generate a short coupon code number

COUPON-{{random_number:1000}}

• Used to create short numeric codes like COUPON-417.

5. 🧾 Generate customer reference number

REF{{random_number:1000000}}

• Example Output: REF492837

💡 Tip

You can also use this inside Format Number, Conditions, API Calls, or Custom Email Templates, just like shown in the screenshot shared below — where it’s used inside a Format Number step to apply a comma separator for readability.