Parameters for the MLT API - Bloomreach Experience - The Headless Digital Experience Platform Built for Commerce

Parameters for the MLT API

Example request

Here’s an example API call for an MLT query, using the product ID, 1000065194:

account_id=<Bloomreach Provided Account ID>
&title=Boys Graphic Tee
API requests should be limited to 16K Bytes. API requests above this length will throw Error Code 414.

The parameter,  pid, in the API call is the product that the MLT suggestions are based on.

All of the parameters in the example call are required parameters for all MLT calls. Your own MLT calls might include optional parameters, but must always include these parameters, too. As a More Like This query, the request_type parameter must be defined with the specific setting, mlt.

Example response

 "response": {
   "numFound": 284,
   "start": 0,
   "docs": [
       "pid": "1000068980",
       "title": "Strapless Tea Length Lace Dress with Sweetheart Neckline"
       "pid": "1000063663",
       "title": "Sleeveless Short Prom Dress with Illusion Lace and Pleated Skirt"
       "pid": "1000065223",
       "title": "Short Lace Prom Dress with Pleated Illusion Neckline"
       "pid": "1000063668",
       "title": "Two Tone Short Prom Dress with Scalloped Lace Illusion Bodice"
       "pid": "1000064025",
       "title": "Glitter Short Prom Dress with Spaghetti Straps and Lace Waist"


Are you integrating your native mobile app (or other non-JS environment) with Bloomreach?

Some of the parameters in your API requests for native mobile apps or non-JS environment need different values from those for your site:

  • _br_uid_2: The value should be the same as described on the Cookie page. Generate a br_uid_2 for your app user and store it in the app permanently if a br_uid_2 does not exist. This br_uid_2 should be used on the corresponding API calls for the app. If the user is on iPhone and resets their IDFA, or if the user is on an Android device and resets their advertising settings: the br_uid_2 should be erased and regenerated the next time the app is set.
  • ref_url: Leave your ref_url parameters empty.
  • url: Use a dummy value for your url parameters, such as

Quick reference: request parameters

This table provides a list of each parameter and a description. A yes flag in the Required column indicates that the parameter is required for all MLT calls, not some.

Parameter Name





account_id yes integer The Bloomreach-provided ID of the account sending the request.  
auth_key yes string The Bloomreach-provided authentication key for the account sending the request. You must pass this parameter, but if your integration is client-side, then you can send it empty. jazzhands
_br_uid_2 yes string

A first-party cookie created by the Bloomreach tracking pixel library (BrTrk). This cookie creates a unique, anonymous identifier for every browser or device.


Don't percent encode this parameter.


pid yes string The unique identifier for a product in the feed. 1005004
brand no string The brand of the product. hugo boss
callback no string (enum)

Indicates whether to return data wrapped into the function when making cross-origin requests.

If you have a server-side integration, then use the value, br_server. If you have a native-app integration, then use the value, br_app.

domain_key yes string The Bloomreach-provided ID of the domain receiving the request. example_com
fl yes string The fields returned with the MLT results, such as the name of products and prices. This value must be a comma-separated list. You must include the pid attribute in your fl parameter value. You can include other attributes from your product feed. pid,title,brand
fq no string

Applies a faceted filter to search results, including only products with the specified attributes . You must surround the value with quotes.

Read more about using fq parameter in the Faceting and filtering page. 

request_id yes string A random ID that enables click-tracking. Use 12 or 13 digits. 1597706996836
request_type yes string (enum)

The request type. Use mlt, which displays an ordered list of similar products.

rows yes integer The number of matching products (documents) returned per results page. The maximum value is 200. To enhance performance, limit this value to the number of products that you think is reasonable for a single page of listings. 30
sort no string

Sorts results based on the field value in ascending, descending, or another combination of orders.

sale_price desc
start yes integer The first page number of results. The maximum value is 500 . 0
title yes string The title or name of the product. *Note: title is used to identify similar products in edge cases to avoid 0 results. Red Monochrome Slingbacks
url yes string The absolute URL of the page where the request is made.

user_id no string The universal customer ID of the user. You only need to pass this field if your particular integration tracks customers this way. 00000
view_id no string A unique identifier for a view of the product catalog. Use a string that identifies the specific site catalog view for your customer. k-3

Detailed reference: request parameters

Some of the request parameters need a little more explanation than others. You can find this extra information here.

domain_key parameter

The Bloomreach-provided ID of the domain receiving the request. This parameter identifies the specific site version when the one account ID hosts multiple site versions with unique characteristics, such as language versions. Bloomreach uses your domain_key parameter value to ensure that only the data that pertains to that site version is used for query and analytics features, such as autosuggestions.

fl parameter

The fl parameter is a comma-separated list of fields returned with MLT results, such as the name of products and prices. The following list is representative of the fields that you can use, but it isn't exhaustive. Your list depends on the values in your product feed.

  • PID is the product ID

  • Title is the title or name of the product

  • URL is the URL of the product description page

  • price is the price of the product

  • sale_price is the price of the product on sale

  • sku_swatch_image is a thumbnail image for a particular sku variation of a product

 fq parameter

The fq parameter applies a faceted filter to the returned products, searching for products that fit your parameter values. Any facet that you want to filter must be in your product feed.

Attributes must be enabled and mapped by Bloomreach

Let your Bloomreach representative know which attributes in your product feed that you want to apply as filters to search results.

Read more about using fq parameter in the Faceting and filtering page. 

request_id Parameter

The request_id parameter value is a random 12 or 13-digit ID that you supply to enable click-tracking. Bloomreach doesn't automatically enforce the requirements for this parameter. For example, you can enter  test  as your value for each instance of the request_id parameter without triggering an error message. However, if you don't use a unique value, then Bloomreach can't help you with potential problems you might experience while using the API.

Sort Parameter

The sort parameter sorts results based on the field value in ascending, descending, or another combination of orders. You can sort any fl field. Some examples are given below:

  • sale_price desc sorts in descending order of the sale price

  • sale_price asc sorts in ascending order of the sale price

  • price_desc sorts in descending order of the price

  • price_asc sorts in ascending order of the price

  • launch_date desc sorts in descending order of the date on which products launched

  • launch_date asc sorts in descending order of the date on which products launched

user_id Parameter

The user_id parameter is a universal customer ID of a user. The parameter captures user IDs from the customer side, and reuses the information when powering apps or enhancing cross-device linking. In this way, Commerce Search and Categories recognizes users in a way that's aligned with your system. Use an anonymous string. Don't use email or other personally identifiable information. If you do not track users this way, then omit this field.

view_id Parameter

The view_id parameter is a unique identifier for a specific view of your product catalog. If you have multiple versions of your site, each with their own product catalog characteristics like product titles and prices, then add view_id to your call. Bloomreach uses your view_id parameter value to display the right product information for your customers based on their individual site views.

You can enter any string value to identify the specific site catalog view. This string must be consistent in your pixel, API, and product catalog. For example, Abacus Thinking sells different academic products to different grade levels. A first grade teacher looks in their Kindergarten through Grade 3 catalog, which Abacus Thinking assigns the ID, k-3:


Consistent, valid values

Your view_id values must be the same in your API, pixel, and product catalog. If Abacus Thinking assigns the value, kindergarten-3rd, to the view_id parameter in their product feed, then the API value, k-3, doesn't match any catalog view.

Quick reference: response parameters

Parameter Name



match A container for the core response details. n/a
numFound The number of records (products) that the MLT response is based on or the number of records that the MLT request retrieves.



The first page number of results .

docs A container for individual documents (products) and their fields . n/a
Using * query
When you use the query '*' as 'q=*' in the API request, the latency of the response will vary depending on your catalog size and it may not adhere to the Bloomreach's standard SLA. Further, please note that except for include/exclude operation, other merchandising operations such as boost/bury or slots do not work on * query parameters.
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