Recs Algorithms Explained

Overview

Netcore Unbxd provides 14 core recommendation algorithms, each powered by a specific signal type and optimised for different page types and user intents.

Let's understand how each algorithm works, their underlying logic, and the minimum data required for reliable performance.

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Before You Start

  • Signal Type refers to the primary source of data an algorithm uses to generate recommendations.
  • Cold Start refers to scenarios where there is insufficient data to generate reliable recommendations.

Available Recommendation Algorithms

Refer to the table below to understand what each recommendation algorithm does.

AlgorithmWhat it does
Top SellersShowcases the most sold products based on historical sales data
Category Top SellersHighlights best-selling products within a category
Recently ViewedShows products viewed by the shopper in recent sessions
Recommended For YouRecommends products based on a shopper’s browsing and product view history
BoutiqueDisplays curated or manually controlled product collections
Cross-SellRecommends complementary products based on business logic
Bought Also BoughtRecommends products frequently purchased together
More Like ThisDisplays similar products using text and category matching
Viewed Also ViewedSuggests products commonly viewed together
AI-based Complete the LookUses AI to automatically generate product combinations
Complete The LookCurates complementary products for a given product
Brand Top SellersHighlights best-selling products within a brand
Recs based on Recently ViewedRecommends products derived from recently viewed items
Recs based on Last ViewedRecommends products based on the most recently viewed product

To access Algorithms, log in to the Netcore Unbxd Recommendation console and navigate to Algorithms > Core Algorithms.

Below is explained how each of the recommendation algorithms works:

Top Sellers

Top Sellers ranks products based on purchase volume within a rolling time window (default: 7 days). A time decay function ensures that recent purchases are weighted more heavily than older ones.

Formula: TopSeller Score(item) = Σ Orders(item, t) * TimeDecay(t) and TimeDecay(t) = e^(-λ * (T - t)) where:

T = current timestamp t = timestamp of each order event λ = decay constant (default ≈ 0.1 per day)

Refer to the table below for Top Sellers details

PropertyValue
StatusActive
Signal TypeSales Analytics
Available OnHome Page, Product Page, Category Page, Cart Page, Brand Page, Journey Page
Minimum Data Required200+ order events
Cold StartNot available; falls back to catalog-based popularity. For example: New Arrivals

Category Top Sellers

It extends the Top Sellers logic to a specific category, surfacing the best-selling products within that category rather than sitewide.

Formula: CategoryTopSeller Score(item, category) = Σ Orders(item, t | category(item) = category) * TimeDecay(t)

Algorithm Details:

PropertyValue
StatusActive
Signal TypeSales Analytics
Available OnProduct Page, Category Page
Minimum Data Required100+ order events (within category)
Cold StartFalls back to Top Sellers (sitewide)

Recently Viewed

It displays products a shopper has viewed, ordered by recency and weighted by frequency. This is a fully personalised, session-aware algorithm.

Formula: RecentlyViewed Score(item, user) = ViewCount(item, user) * TimeDecay(last_view_time)

Algorithm Details:

PropertyValue
StatusActive
Signal TypeUser Activity (Views)
Available OnHome Page, PDP
Minimum Data Required1 product view per user
Cold StartFully available from the first session

Recommended For You

Builds a user-specific interest profile using past interactions (clicks, cart, purchase) and recommends products with similar attributes.

Formula: User Interest Profile(user) = Σ [EventWeight(event) * AttributeVector(item)] RecommendedForYou Score(item, user) = cosine_similarity(AttributeVector(item), User Interest Profile(user)) where

AttributeVector(item) = product attributes (category, brand, price tier, tags, keywords) EventWeight = Order > Cart > Click cosine_similarity = similarity score between vectors

Algorithm Details:

PropertyValue
StatusActive
Signal TypeBehavioral + Catalog
Available OnHome Page, PDP
Minimum Data Required3+ behavioral events per user
Cold StartFalls back to Top Sellers or Trending

Boutique

A scoped version of Recommended For You, restricted to a specific boutique or brand catalog. It provides personalization within a curated variety. It uses the same user interest profiling logic.

Algorithm Details

PropertyValue
StatusActive
Signal TypeBehavioral + Catalog
Available OnBoutique Pages
Minimum Data Required3+ events per user; 20+ SKUs recommended
Cold StartSame fallback as Recommended For You

Cross Sell

It identifies categories that are frequently used together and recommends products from complementary categories.

Formula: CategoryAffinity(Cat_A, Cat_B) = |Users who interacted with both Cat_A and Cat_B| / sqrt(|Users Cat_A| * |Users Cat_B|)

Algorithm Details:

PropertyValue
StatusActive
Signal TypeBehavioral (Category Affinity)
Available OnPDP, Cart
Minimum Data Required2,000+ events; 300+ users
Cold StartNot available

Bought Also Bought

It identifies products frequently purchased by the same users over time, building item-to-item relationships.

Formula: BoughtAlsoBought Score(A, B) = |Users who purchased both A and B| / sqrt(|Users A| * |Users B|)

Algorithm Details:

PropertyValue
StatusActive
Signal TypePurchase Behavior
Available OnPDP
Minimum Data Required500+ purchase events
Cold StartNot available

More Like These

It uses semantic similarity across product attributes (title, description, category, brand, tags) to find similar items.

Algorithm Details

PropertyValue
StatusActive
Signal TypeCatalog / Text Embeddings
Available OnProduct Page, Cart Page
Minimum Data RequiredCatalog data only
Cold StartFully available from day one

AI-Based Complete The Look

This Algorithm generates product combinations based on visual and stylistic compatibility.

Formula: CTL Score(A, B) = α * VisualCompatibility(img_A, img_B) + β * StyleAttributeMatch(attr_A, attr_B) + γ * CategoryComplementarity(cat_A, cat_B) where,

α + β + γ = 1 (weights calibrated per client)

Algorithm Details

PropertyValue
StatusActive
Signal TypeVisual AI + Catalog
Available OnComplete The Look Page
Minimum Data RequiredImages and style attributes
Cold StartFully available with catalog

Complete The Look (Editorial)

It works on manual product associations defined by merchandisers.

Algorithm Details:

PropertyValue
StatusInactive
Signal TypeEditorial
Available OnComplete The Look Page
Minimum Data RequiredManual configuration
Cold StartNot applicable

Recommendations Based on Recently Viewed

This algorithm uses recently viewed products as seeds to recommend new, similar products that the shopper hasn't seen yet.

Formula: RecsFromRecentlyViewed Score(candidate, user) = Σ [TimeDecay(view_t) * cosine_similarity(AttributeVector(candidate), AttributeVector(seed_item))]

Algorithm Details:

PropertyValue
StatusActive
Signal TypeUser Activity + Similarity
Available OnHome Page, PDP
Minimum Data Required1+ views (optimal at 5+)
Cold StartFalls back to Top Sellers / Recommended For You

Recommendations Based on Last Viewed

This uses the most recently viewed product as the primary intent signal to generate focused recommendations.

Formula: RecsFromLastViewed Score(candidate, user) = α * cosine_similarity(AttributeVector(candidate), AttributeVector(LastViewedItem(user))) + β * BoughtAlsoBought Score(candidate, LastViewedItem(user)) where:
α + β = 1 (default: α = 0.6, β = 0.4)

Algorithm Details

PropertyValue
StatusActive
Signal TypeUser Activity + Hybrid
Available OnHome Page, PDP, Category Page, Cart Page
Minimum Data Required1 product view
Cold StartFully available from the first session