diff --git a/web/database/worker/db-worker.js b/web/database/worker/db-worker.js
--- a/web/database/worker/db-worker.js
+++ b/web/database/worker/db-worker.js
@@ -2,7 +2,13 @@
 
 import localforage from 'localforage';
 
-import { type SharedWorkerMessageEvent } from '../../types/worker-types.js';
+import {
+  type SharedWorkerMessageEvent,
+  type WorkerRequestMessage,
+  type WorkerResponseMessage,
+  workerRequestMessageTypes,
+  workerResponseMessageTypes,
+} from '../../types/worker-types.js';
 
 const localforageConfig: PartialConfig = {
   driver: localforage.INDEXEDDB,
@@ -13,6 +19,19 @@
 };
 localforage.config(localforageConfig);
 
+function processAppRequest(
+  message: WorkerRequestMessage,
+): ?WorkerResponseMessage {
+  if (message.type === workerRequestMessageTypes.PING) {
+    return {
+      type: workerResponseMessageTypes.PONG,
+      text: 'PONG',
+    };
+  }
+
+  throw new Error('Request type not supported');
+}
+
 function connectHandler(event: SharedWorkerMessageEvent) {
   if (!event.ports.length) {
     return;
@@ -21,9 +40,16 @@
   console.log('Web database worker alive!');
 
   port.onmessage = async function (messageEvent: MessageEvent) {
-    console.log('message from main thread: ', messageEvent.data);
+    const message: WorkerRequestMessage = (messageEvent.data: any);
 
-    port.postMessage({ message: 'response from worker' });
+    try {
+      const result = processAppRequest(message);
+      port.postMessage(result);
+    } catch (e) {
+      port.postMessage({
+        error: e,
+      });
+    }
   };
 }
 
diff --git a/web/types/worker-types.js b/web/types/worker-types.js
--- a/web/types/worker-types.js
+++ b/web/types/worker-types.js
@@ -1,5 +1,35 @@
 // @flow
 
+// The types of messages sent from app to worker
+export const workerRequestMessageTypes = Object.freeze({
+  PING: 0,
+});
+
+export type PingWorkerRequestMessage = {
+  +type: 0,
+  +text: string,
+};
+
+export type WorkerRequestMessage = PingWorkerRequestMessage;
+
+// The types of messages sent from worker to app
+export const workerResponseMessageTypes = Object.freeze({
+  PONG: 0,
+});
+
+export type ErrorWorkerResponseMessage = {
+  +error: Error,
+};
+export type PongWorkerResponseMessage = {
+  +type: 0,
+  +text: string,
+};
+
+export type WorkerResponseMessage =
+  | PongWorkerResponseMessage
+  | ErrorWorkerResponseMessage;
+
+// SharedWorker types
 export type SharedWorkerMessageEvent = MessageEvent & {
   +ports: $ReadOnlyArray<MessagePort>,
   ...