diff --git a/requirements.txt b/requirements.txt
index 1f82926..98952d9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,4 +5,5 @@ sssom-schema
 sssom
 oaklib==v0.1.71
 pydantic[dotenv]
-curies
\ No newline at end of file
+curies
+toolz
\ No newline at end of file
diff --git a/src/models.py b/src/models.py
index fb93fb0..0d731bc 100644
--- a/src/models.py
+++ b/src/models.py
@@ -7,11 +7,6 @@
 from sssom_schema import Mapping, MappingSet, MappingRegistry, MappingSetReference
 
 T = TypeVar("T")
-# class ResponseMapping(BaseModel):
-#   subject_id: Mapping.subject_id
-#   predicate_id: Mapping.predicate_id
-#   object_id: Mapping.object_id
-#   mapping_justification: Mapping.mapping_justification
 
 class PaginationParams(BaseModel):
   request: Request
@@ -30,9 +25,15 @@ class PaginationInfo(BaseModel):
   total_pages: int
 
 
+class FacetInfo(BaseModel):
+  mapping_justification: dict
+  predicate_id: dict
+
+
 class Page(GenericModel, Generic[T]):
   data: List[T]
   pagination: PaginationInfo
+  facets: FacetInfo
 
 
 class SearchEntity(BaseModel):
diff --git a/src/utils.py b/src/utils.py
index ff3a802..bad591b 100644
--- a/src/utils.py
+++ b/src/utils.py
@@ -1,12 +1,13 @@
 
 from typing import Iterable, TypeVar, Union, List
 import itertools
-import functools
 import math
+from toolz.recipes import countby
+from toolz.itertoolz import count
 
 from fastapi import Request
 
-from .models import Page, PaginationInfo
+from .models import Page, PaginationInfo, FacetInfo
 
 
 def _replace_page_param(request: Request, new_page: Union[int, None]) -> Union[str, None]:
@@ -24,8 +25,8 @@ def paginate(iterable: Iterable[T], page: int, limit: int, request: Request) ->
     prev_page = None
     next_page = None
     data = []
-    iter_data, iter_total = itertools.tee(iterable)
-    total_items = functools.reduce(lambda prev, curr: prev + 1, iter_total, 0)
+    iter_data, iter_total, iter_facets = itertools.tee(iterable, 3)
+    total_items = count(iter_total)
     total_pages = math.ceil(total_items / limit)
     for idx, item in enumerate(iter_data):
         if idx == start - 1:
@@ -44,6 +45,15 @@ def paginate(iterable: Iterable[T], page: int, limit: int, request: Request) ->
             total_items=total_items,
             total_pages=total_pages
         ),
+        facets=_create_facets(iter_facets)
+    )
+
+def _create_facets(data: Iterable[T]) -> FacetInfo:
+    iter_mj, iter_pred = itertools.tee(data)
+    
+    return FacetInfo(
+        mapping_justification=countby(lambda d: d["mapping_justification"], iter_mj),
+        predicate_id=countby(lambda d: d["predicate_id"], iter_pred),
     )
 
 def parser_filter(datamodel: T, filter: Union[List[str], None] = None) -> Union[List[dict], None]: