Personalization opportunity
They want it. It's out of stock.
Show something in stock that fits, and a waitlist that actually writes back.
Step 1 · Signals
What do we know about this person?
Declared
The product, size, or query they asked for.
Connected
Prior purchase of that line, or a saved size.
Example eligibility rule
Trigger when the selected variant is unavailable and the visitor has either attempted to add it or viewed the PDP at least twice. Rank substitutes only when they match the selected size or compatibility requirement, remain within 20% of the original price, and share the product's primary use.
Step 2 · The need
What’s really going on?
A PDP, a search hit, or a rec points at something you cannot sell today. Default is a grey button. No nearest size, no similar in-stock, no waitlist they can actually use.
Avoid this assumption
A notify-me form is not a substitute. Showing the next best in-stock item, with a reason, is.
Step 3 · Worth it?
Do the math before you build.
High intent plus unavailability is a fork: recover to a substitute, capture the wait, or lose them to a competitor who has it.
Reach
How many eligible people can you reach in the chosen channel and time period?
Cost
What will content, delivery, QA and ongoing maintenance cost?
Return
What incremental outcome would cover that cost, and what is it worth?
Planning inputs, not measured results. Estimate reach × incremental outcome rate × value per outcome, then subtract cost. Use a range and a consistent time period.
Step 4 · The response
Pick how you help.
Example format: Recommendations
Lead with in-stock alternatives that match the attribute they cared about.
Compare lighter and deeper responses
Choose the lightest response that solves the need.
Assist: Offer useful help
Keep the OOS page. A waitlist and one similar in-stock card.
Adapt: Change a meaningful part
Lead with in-stock alternatives that match the attribute they cared about.
Transform: Tailor the journey
Substitute-first layout, waitlist, and a "we'll hold it" path if restock is near.
What to watch out for
- Pushing a more expensive substitute without saying so.
- Waitlists that never fire.
- Hiding OOS so search looks full, then failing at cart.
Step 5 · The moment
Did it help? A/B test it.
Control
Default out-of-stock PDP or result.
Treatment
Substitute-and-wait recovery.
Success measure
Conversion to an in-stock alternative, plus waitlist quality.
Guardrail
Returns on the substitute. A bad swap is worse than a waitlist.
Among visitors who met the out-of-stock rule, compare substitute engagement, alternative-item conversion, and waitlist joins with the default out-of-stock experience. Break results out by declared size, saved size, and inferred product interest.
Win or lose, record what worked, for whom and why. What you learn becomes the next signal.
Tools that can deliver the response
- Bloomreach Ecommerce Search AI-driven ecommerce search and discovery platform (Loomi AI) that personalizes ranking, recommendations, and merchandising from first-party shopper data.
- Nosto AI commerce platform combining personalized search, recommendations, merchandising, and content/A-B testing under one data layer.
- Constructor Ecommerce search and recommendations platform that optimizes recs against a chosen business KPI using clickstream data and merchant rules.
- Klaviyo Behavior-triggered email and SMS with real-time customer profiles and segments, built for ecommerce.
Try the framework on another situation
Search came back with nothing they can use. Show a close match for what they typed.
They searched for something specific. You showed bestsellers. Put what they asked for first.
Work through it in the hub
Score your personalization program, explore more customer situations, and compare the tools that can deliver them.
.svg)
