diff --git a/drift_matrix_visualization/js/api.js b/drift_matrix_visualization/js/api.js
new file mode 100644
index 0000000..d1d40d6
--- /dev/null
+++ b/drift_matrix_visualization/js/api.js
@@ -0,0 +1,48 @@
+/**
+ * @module api
+ * Data layer module for fetching Drift-Matrix data.
+ *
+ * Provides a function to retrieve matrix data from the backend.
+ */
+
+/**
+ * Fetches Drift-Matrix data from the API for a given run.
+ *
+ * @async
+ * @function fetchMatrixData
+ * @param {string|number} run_id - The identifier of the run for which drift data should be retrieved.
+ * @returns {Promise<Array<{quadrant: string, warn_reasons: string[], counts: number[]}>>} - The matrix data as JSON array.
+ * @throws {Error} Throws if the fetch fails or response is invalid.
+ */
+export async function fetchMatrixData(run_id) {
+  if (!run_id) {
+    throw new Error('fetchMatrixData: Missing required parameter run_id');
+  }
+
+  const url = new URL('/drift-matrix', window.location.origin);
+  url.searchParams.append('run_id', run_id);
+
+  try {
+    const response = await fetch(url.toString(), {
+      method: 'GET',
+      headers: {
+        'Accept': 'application/json'
+      }
+    });
+
+    if (!response.ok) {
+      throw new Error(`API request failed with status ${response.status}`);
+    }
+
+    const data = await response.json();
+
+    if (!Array.isArray(data)) {
+      throw new Error('Invalid API response format: expected an array');
+    }
+
+    return data;
+  } catch (error) {
+    console.error('Error fetching drift matrix data:', error);
+    throw error;
+  }
+}