diff --git a/appapi.yaml b/appapi.yaml
index f22166f3a379aaad1952dadc3fca16ac27c325a5..71556bb4558a2276a11fac2b98aec6a423cbb79e 100755
--- a/appapi.yaml
+++ b/appapi.yaml
@@ -83,6 +83,56 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/error'
+  '/user/search':
+    get:
+      summary: Search for users by their username.
+      description: >-
+        Returns an array of objects representing the app users
+        whose usernames start with the search term.
+        Casing is ignored.
+        The user objects are stripped down to what is necessary
+        to know as an app user.
+      parameters:
+        - name: s
+          description: The term to search for. Must be at least two characters.
+          in: query
+          required: true
+          schema:
+            type: string
+            minLength: 2
+      responses:
+        '200':
+          description: Success
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/userinfo'
+        '400':
+          description: Search term is invalid.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/input-error'
+        '401':
+          description: Authentication failure.
+          content:
+            text/plain:
+              schema:
+                type: string
+        '500':
+          description: The server cannot deliver due to an internal error.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/internal-error'
+        default:
+          description: Some unexpected error.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/error'
   '/user':
     get:
       summary: Get the data of the user.