diff --git a/shared/http/middleware.go b/shared/http/middleware.go
index 8de39ad..b993c85 100644
--- a/shared/http/middleware.go
+++ b/shared/http/middleware.go
@@ -1,29 +1,59 @@
 package http
 
-import "net/http"
+import (
+	"context"
+	"errors"
+	"net/http"
+)
 
-func CorsMiddleware(next http.Handler, origin string) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Set("Access-Control-Allow-Credentials", "true")
-		w.Header().Set("Access-Control-Allow-Methods", "POST,GET")
-		w.Header().Set("Access-Control-Allow-Origin", origin)
-		next.ServeHTTP(w, r)
-	})
+func CorsMiddleware(origin string) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Access-Control-Allow-Credentials", "true")
+			w.Header().Set("Access-Control-Allow-Methods", "POST,GET")
+			w.Header().Set("Access-Control-Allow-Origin", origin)
+			next.ServeHTTP(w, r)
+		})
+	}
 }
 
-func ContentTypeMiddleware(next http.Handler, contentType string) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Add("Content-Type", contentType)
-		next.ServeHTTP(w, r)
-	})
+func ContentTypeMiddleware(contentType string) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Add("Content-Type", contentType)
+			next.ServeHTTP(w, r)
+		})
+	}
 }
 
-func OptoutMiddleware(next http.Handler) http.Handler {
-	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if _, err := r.Cookie("optout"); err == nil {
-			w.WriteHeader(http.StatusNoContent)
-			return
-		}
-		next.ServeHTTP(w, r)
-	})
+func OptoutMiddleware(cookieName string) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if _, err := r.Cookie(cookieName); err == nil {
+				w.WriteHeader(http.StatusNoContent)
+				return
+			}
+			next.ServeHTTP(w, r)
+		})
+	}
+}
+
+func UserCookieMiddleware(cookieKey string, contextKey interface{}) func(http.Handler) http.Handler {
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			c, err := r.Cookie(cookieKey)
+			if err != nil {
+				RespondWithJSONError(w, err, http.StatusBadRequest)
+				return
+			}
+			if c.Value == "" {
+				RespondWithJSONError(w, errors.New("received blank user identifier"), http.StatusBadRequest)
+				return
+			}
+			r = r.WithContext(
+				context.WithValue(r.Context(), contextKey, c.Value),
+			)
+			next.ServeHTTP(w, r)
+		})
+	}
 }
diff --git a/shared/http/middleware_test.go b/shared/http/middleware_test.go
index bb21a4e..6b4fb56 100644
--- a/shared/http/middleware_test.go
+++ b/shared/http/middleware_test.go
@@ -8,9 +8,9 @@ import (
 
 func TestCorsMiddleware(t *testing.T) {
 	t.Run("default", func(t *testing.T) {
-		wrapped := CorsMiddleware(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		wrapped := CorsMiddleware("https://www.example.net")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			w.Write([]byte("OK"))
-		}), "https://www.example.net")
+		}))
 		w := httptest.NewRecorder()
 		r := httptest.NewRequest(http.MethodGet, "/", nil)
 		wrapped.ServeHTTP(w, r)
@@ -22,9 +22,9 @@ func TestCorsMiddleware(t *testing.T) {
 
 func TestContentTypeMiddleware(t *testing.T) {
 	t.Run("default", func(t *testing.T) {
-		wrapped := ContentTypeMiddleware(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		wrapped := ContentTypeMiddleware("application/json")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			w.Write([]byte("OK"))
-		}), "application/json")
+		}))
 		w := httptest.NewRecorder()
 		r := httptest.NewRequest(http.MethodGet, "/", nil)
 		wrapped.ServeHTTP(w, r)
@@ -35,7 +35,7 @@ func TestContentTypeMiddleware(t *testing.T) {
 }
 
 func TestOptoutMiddleware(t *testing.T) {
-	wrapped := OptoutMiddleware(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+	wrapped := OptoutMiddleware("optout")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte("hey there"))
 	}))
 	t.Run("with header", func(t *testing.T) {