How you ship variants¶
You build version B; Squoosh tests your real change and never generates or edits the variant. It needs to know how to reach the version you built. In an A/B test, the Variant section asks How do you ship variants? and gives you three ways to answer. This page explains each one and which to use.
The three modes¶
| Mode | Use it when | What you provide |
|---|---|---|
| Two URLs | Each version lives at its own web address. | The Variant page (B) URL. |
| VWO / Optimizely / AB Tasty | A client-side testing tool shows the variant on a single URL. | Preview URLs, or the experiment and variation IDs. |
| Feature flag | Your server selects the version from a flag (LaunchDarkly, Statsig, Split, or custom). | The flag mechanism and its control and variant values. |
Two URLs is selected by default and is the proven path. The two vendor-based modes are early and still in validation — see Vendor and feature-flag modes below.
Two URLs¶
Use Two URLs when your Control page (A) and Variant page (B) have separate web addresses. This is the verified setup and the one to use whenever you can host the variant at its own URL.
You entered the Control (A) URL earlier in the wizard. In the Variant section:
- Select Two URLs if it is not already selected.
- Enter the Variant page (B) URL.
The Variant (B) URL must be a valid address and must differ from the Control (A) URL. Two distinct URLs run a true A/B test, so Squoosh does not let you point the variant at the control. When the URL is valid and distinct, the wizard confirms it with Looks valid · differs from control.
Vendor and feature-flag modes¶
If your variant is served on the same URL as your control — by a client-side testing tool or a server-side flag — use one of the two modes below. With both versions on a single URL, you tell Squoosh how to reach each one. This is expected for these setups; only Two URLs needs two distinct addresses.
Note
These two modes are early and still being validated. If you use VWO, Optimizely, AB Tasty, LaunchDarkly, Statsig, Split, or a custom flag, contact the Squoosh team at support@squoosh.ai to set the experiment up. Use Two URLs for any test where you can host the variant at its own address.
VWO / Optimizely / AB Tasty¶
Use this mode when a client-side tool shows different visitors a different version on one URL.
- Select VWO / Optimizely / AB Tasty.
- Choose your Vendor: VWO, Optimizely, or AB Tasty.
- Tell Squoosh how to reach each version, one of two ways:
- Preview URLs — enter the Control (A) preview URL and the Variant (B) preview URL.
- Experiment + variation IDs — enter the Experiment ID, the Variation ID for Control (A), and the Variation ID for Variant (B).
Feature flag¶
Use this mode when your server picks the version from a flag value.
- Select Feature flag.
- Choose your Vendor if you use one: LaunchDarkly, Statsig, or Split. Leave it on Custom / none for any other flag.
- Choose how your server reads the flag: a Cookie, a Header, or a Query param, and name it.
- Enter the Control (A) value and the Variant (B) value — the flag values that select each version.
If Squoosh detects your testing tool¶
When you enter a control URL that Squoosh recognizes as running a client-side testing tool, it switches to the matching vendor mode for you and shows a banner naming the tool. To go back, choose Two URLs in the banner or pick a mode yourself.
If Squoosh can't tell the versions apart¶
After a run, Squoosh checks that the two versions it captured differ from each other. If they look identical, it shows a warning above the verdict instead of reporting a result you can't trust. This usually means the variant didn't apply during the run — most often because a same-URL tool showed both versions the same page. Recheck the preview URLs, IDs, or flag values you entered for the variant, then run the experiment again.