diff --git a/data/backend-definition.yaml b/data/backend-definition.yaml
new file mode 100644
index 0000000..1849f19
--- /dev/null
+++ b/data/backend-definition.yaml
@@ -0,0 +1,139 @@
+openapi: 3.0.0
+info:
+  title: ToDo API
+  version: 1.0.0
+  description: ToDo App API
+
+components:
+  schemas:
+    ToDoItem:
+      type: object
+      properties:
+        id:
+          type: string
+          format: uuid
+        title:
+          type: string
+          example: "Learn OpenAPI"
+        order:
+          type: integer
+          example: 2
+        completed:
+          type: boolean
+          example: false
+        url:
+          type: string
+          format: uri
+          example: http://localhost:8080/todo?id=1234-5678-9012-3456
+paths:
+  /:
+    get:
+      summary: retrieves a list of the current ToDo items
+      description: returns a list of the current ToDo items
+      responses:
+        '200':
+          description: a json array of ToDo items
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/ToDoItem'
+    post:
+      summary: creates a new ToDo item
+      description: returns the created ToDo item
+      requestBody:
+        description: the ToDo item to create
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/ToDoItem'
+      responses:
+        '200':
+          description: the created ToDo item
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ToDoItem'
+    delete:
+      summary: deletes all ToDo items
+      description: returns the remaining ToDo items (none)
+      responses:
+        '200':
+          description: empty array of ToDo items
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/ToDoItem'
+  /?id={id}:
+    get:
+      summary: retrieve a single ToDo item specified by id
+      description: returns a single ToDo item
+      parameters:
+        - name: id
+          in: query
+          description: the id of the ToDo item
+          required: true
+          schema:
+            type: string
+            format: uuid
+      responses:
+        '200':
+          description: a json object of ToDo item
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ToDoItem'
+        '404':
+          description: ToDo item not found
+    patch:
+      summary: updates a ToDo item
+      description: return the updated ToDo item
+      parameters:
+        - name: id
+          in: query
+          description: the id of the ToDo item
+          required: true
+          schema:
+            type: string
+            format: uuid
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/ToDoItem'
+      responses:
+        '200':
+          description: the updated ToDo item
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ToDoItem'
+        '404':
+          description: ToDo item not found
+    delete:
+      summary: deletes a single ToDo item
+      description: return the remaining ToDo items following the delete operation
+      parameters:
+        - name: id
+          in: query
+          description: the id of the ToDo item
+          required: true
+          schema:
+            type: string
+            format: uuid
+      responses:
+        '200':
+          description: single ToDo item deleted, returns remaining ToDo items
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/ToDoItem'
+        '404':
+          description: ToDo item not found
\ No newline at end of file
diff --git a/source/index.html.erb b/source/index.html.erb
index 56c06f2..8cf741c 100644
--- a/source/index.html.erb
+++ b/source/index.html.erb
@@ -6,7 +6,7 @@
       </header>
 
       <article class="intro">
-        <p>The Todo-Backend project defines a simple web API spec - for managing a todo list. Contributors <a href="/contribute.html">implement</a> that spec using various tech stacks. Those implementations are cataloged below. A <a href="/specs/index.html">spec runner</a> verifies that each contribution implements the exact same API, by running an automated test suite which <a href="https://github.com/TodoBackend/todo-backend-js-spec/blob/master/js/specs.js">defines</a> the API.
+        <p>The Todo-Backend project defines a simple web API spec - for managing a todo list. Contributors <a href="/contribute.html">implement</a> that spec using various tech stacks. Those implementations are cataloged below. A <a href="/specs/index.html">spec runner</a> verifies that each contribution implements the exact same API, by running an automated test suite which <a href="https://github.com/TodoBackend/todo-backend-js-spec/blob/master/js/specs.js">defines</a> the API. The API specification is also available as an <a href="/data/backend-definition.yaml">OpenAPI (Swagger) spec</a>.
           <br><br>
           The Todo-Backend project was inspired by the <a href="http://todomvc.com/">TodoMVC project</a>, and some code
           (specifically the todo client app) was borrowed directly from TodoMVC.