A custom algorithm is your own recommendation logic, built from Netcore Unbxd's in built algorithms. Build a single algorithm or a hybrid (a combination of up to three), then control how products are selected, ranked across the slots, filtered, and filled in when supply runs short.

You build custom algorithms in the Custom Algorithm Builder, opened from the Algorithms page.

Custom Algorithm Builder

1. On the Manage Algorithms page, click Create Custom Algorithm. The Algorithm Details page opens.
2. In Algorithm Name type a unique name. The name can't repeat an existing algorithm name.

Add primary algorithms

Under Primary algorithms, assign up to 3 algorithms across the 18 slots.

3. From the Algorithm 1 dropdown, select an algorithm. The dropdown lists in built algorithms only (for example, Cross sell, Complete the look, Top Sellers, Recommended For You, Recently Viewed). You can't nest another custom algorithm.
4. Set the Slots range this algorithm fills, for example 1 to 18. You enter the starting and ending slot manually.
5. To build a hybrid, click Add Algorithm and repeat. The button shows a running count, such as Add Algorithm (1/3), and is disabled once you reach three. To remove an added algorithm, click the delete (trash) icon on its row.
6. Check the Slot coverage indicator (for example, 18/18). Each algorithm is assigned its own colour, and the slot-coverage boxes use the same colours so you can see at a glance how the slots are divided.

Filters

7. Under Filters ("Narrow down the catalog of products this algorithm is allowed to choose from"), click Add filters.
8. In the Filters dialog, set an Attribute, an Operator (for example, Include or Exclude), and Values. Each value can be:
   • Dynamic: Matched against the anchor product on the page, for example "Same activationDate as the anchor product." Dynamic filters apply on product pages with More Like This, Recommended For You, Recently Viewed, Cross-Sell, and Complete the Look.
   • Static: A fixed value you choose.
9. Click the + icon to add more rules, Clear all Filters to reset, then Save.

Fallbacks

Fallbacks control what displays when your primary algorithms can't return enough products to fill all 18 slots.

10. Turn on Enable Fallbacks. The builder reveals a fallback chain in two stages:

    • Under If primary returns fewer than 18 products, set the Fallback Algorithm ("If your primary algorithm can't find enough products, we'll pull products from this algorithm instead"). Select a single out-of-the-box algorithm; a hybrid fallback isn't supported. Select Apply Filters to Fallback to run the same filters on it.
    • Under If fallback algorithm also fails, add Fallback Product Ids ("If both primary and fallback algorithms fail, these hand-picked products will be shown in the order selected"). Open Select Unique ID, search by title or uniqueId, and select products. They render in the order you pick them. There's no limit on how many you add, but you can only select products that exist in your feed. Free-typed or non-existent IDs are rejected.

    If Enable Fallbacks is off, any unfilled slots are left empty or filled by the platform-set fallback for that algorithm.

Save and preview

11. Click Save.
12. Use the Preview pane to check results: Preview recommendations for a product ID or in a category, and, optionally, personalized for a selected user. You must save the algorithm before previewing.

Edit Custom Algorithm

Click Edit on a custom algorithm row to reopen the builder with every saved value pre-filled and editable: the name, primary algorithms, slot assignments, filters, and fallbacks. Click Save to commit.

An edit applies immediately, including to any experiences already using the algorithm.

Edit a Core Algorithm

To base a new algorithm on an in built algorithm, click Duplicate on a Configurable or Read Only row. The builder opens pre-seeded with that core algorithm as Algorithm 1. Extend it with more algorithms, filters, or fallbacks, then save it as a new custom algorithm. The source core algorithm is never changed.

This is also the way to customise a Read Only algorithm, which can't be edited directly.

Backward compatibility

Existing custom algorithms and fallbacks that don't meet the current limits (for example, hybrid fallbacks or more than three combined algorithms) continue to be served as-is.

If you click Edit on one of them, you can make changes, but the algorithm is only saveable once it meets the limits. If you'd rather not bring it within the limits, leave it. It keeps working exactly as before.