A/B split: send runs down different paths by percentage

In this article:

• What the A/B step does
• Add an A/B step
• Round robin and Balancing
• Add more than two variants
• See which path a run took
• Ideas for A/B tests

The A/B step splits the runs of a workflow between two or more paths. For example, half of your customers get a 10% discount code and the other half get free shipping, so you can compare which offer works better.

What the A/B step does

Each time the workflow reaches the A/B step, React Flow sends that run down one of its paths: A, B, C and so on. You decide how the runs are shared between the paths. Each path can have its own conditions, delays and actions.

Add an A/B step

1. Open a workflow and click + where you want to split it, for example under the trigger.
2. Select A/B. An A/B Testing step appears with the outputs A and B.
3. In the right panel (Configure switch action), choose the Algorithm type: Round robin or Balancing.
4. Click + under A and add the steps for the first variant. Do the same under B.
5. Click Save.

Round robin and Balancing

• Round robin: "Next action is chosen evenly and in rotation to each test variation." The runs go to A, then B, then A again, and so on, so each path gets the same share.
• Balancing: "Next action is chosen based on the percentage you set for each one." Drag the slider to set the share of each path, for example 70% for A and 30% for B. The step shows the result on the canvas, for example Balancing : 70%/30%.

Use Round robin for a fair 50/50 comparison. Use Balancing when you want to try a new idea on a small part of the traffic first, for example 90% keep the current email and 10% get the new one.

Add more than two variants

When you connect a step to the last free output, a new output appears. Connect a step to B, and C appears; connect C, and D appears. The free output at the end is ignored until you connect something to it.

With Balancing, the slider gets one handle for each border between paths, and the shares are recalculated, for example 30%/30%/40% for three paths.

There is a ready-made example in Templates - Coupon for next orders with balanced distribution: it splits customers into three groups (50%, 40% and 10%) and sends each group a different discount (5%, 10% and 15%).

See which path a run took

Open a run on the Activity page or in a test result. The A/B step is shown as Switch lane... with the chosen path, for example Balancing - C:40%.

To compare the results of the paths, tag each path differently, for example add the order tag variant-a in path A and variant-b in path B. Then filter orders or customers by these tags in Shopify.

Ideas for A/B tests

• Discount size: 10% off in path A, 15% off in path B, for the same win-back email.
• Offer type: a percentage discount in path A, free shipping in path B.
• Timing: a review request after 3 days in path A and after 7 days in path B (add a Delay in each path).
• Message: two different subject lines for the same email.

✔️ Next step

Check our articles to learn more about the app's functionality:

• Components of the workflow
• Activity page
• React Flow templates

Updated on: 20/10/2026