Links & destinations
Split testing
Send traffic across up to eight weighted destinations behind one short link, and read the results as drift against your allocation.
A split test is active when a Standard URL or UTM link has at least two named destinations. Each destination has a weight (positive integer). Traffic is distributed in proportion to those weights. You can define up to eight variations.
How to set it up
- Create or edit a Standard URL or Link with UTM.
- Open Split test destinations.
- Add at least two rows: a short name (for example
controlandhero-b), a https URL, and a weight. - Save. The first URL remains the canonical destination shown in lists; clicks still go to whichever variation is chosen.
How a variation is chosen
On each visit Letlink rolls against the weights. The chosen name is stored on the click as variation (webhook field visitor_variation). Analytics, CSV export, the API and every notification integration all show it.
How do I read the results?
The Split test panel on the link's stats page reports each destination's *actual share of traffic against the share you allocated it*. That difference — labelled drift — is the number worth reading. Raw click counts on a weighted split mostly restate the weights you set: a destination given 50% of the traffic will receive roughly 50% of the clicks whether or not it is any good. Drift is what tells you something changed.
- Allocated — the share implied by the weights you set.
- Received — the share of clicks that actually landed on that destination.
- Drift — the gap between them, in percentage points. A few points either way is ordinary randomness.
- Visitors — unique devices that reached that destination, so you can tell wide reach from one enthusiastic refresher.
Below roughly 100 total clicks the panel says so and shows progress toward that mark instead of naming a leader. Two arms separated by a handful of clicks on a small sample are not distinguishable, and a dashboard that implies otherwise is worse than one that admits it.
Force a variation
Append ?vr=NAME to the short URL to skip the roll and send that visitor to the named destination. Useful for QA and for sending a teammate a specific creative. An unknown name is ignored and the weighted pick runs as usual — and because the variation recorded on the click is always the destination actually served, a stray ?vr= value can never pollute your breakdowns.
https://letl.ink/summer?vr=hero-b