diff --git a/package-lock.json b/package-lock.json
index 9285148..2f362c7 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -40,7 +40,7 @@
         "topola": "^3.6.1",
         "turbocommons-ts": "^3.8.0",
         "unified": "^10.1.0",
-        "wikitree-js": "^0.1.0"
+        "wikitree-js": "^0.4.0"
       },
       "devDependencies": {
         "@types/array.prototype.flatmap": "^1.2.2",
@@ -25403,9 +25403,9 @@
       "dev": true
     },
     "node_modules/wikitree-js": {
-      "version": "0.1.0",
-      "resolved": "https://registry.npmjs.org/wikitree-js/-/wikitree-js-0.1.0.tgz",
-      "integrity": "sha512-ztMf+tAAO6/4GofAqhBYL3iMlMqYraI3/pYn8qWpaa2feLYJU5rjMJaIPACaJaBHjXOUTaOR0NSQ46drObjzhA==",
+      "version": "0.4.0",
+      "resolved": "https://registry.npmjs.org/wikitree-js/-/wikitree-js-0.4.0.tgz",
+      "integrity": "sha512-ZNlXbm9RiLQ0oZ7m4CotsYafeQ4YKJuRdxC/OcjjSvhVf16nAhocw5fTjhMBq9EKnXvK5+F7+k+nULdQFXDyIg==",
       "dependencies": {
         "cross-fetch": "^3.1.5",
         "form-data": "^4.0.0",
@@ -46170,9 +46170,9 @@
       "dev": true
     },
     "wikitree-js": {
-      "version": "0.1.0",
-      "resolved": "https://registry.npmjs.org/wikitree-js/-/wikitree-js-0.1.0.tgz",
-      "integrity": "sha512-ztMf+tAAO6/4GofAqhBYL3iMlMqYraI3/pYn8qWpaa2feLYJU5rjMJaIPACaJaBHjXOUTaOR0NSQ46drObjzhA==",
+      "version": "0.4.0",
+      "resolved": "https://registry.npmjs.org/wikitree-js/-/wikitree-js-0.4.0.tgz",
+      "integrity": "sha512-ZNlXbm9RiLQ0oZ7m4CotsYafeQ4YKJuRdxC/OcjjSvhVf16nAhocw5fTjhMBq9EKnXvK5+F7+k+nULdQFXDyIg==",
       "requires": {
         "cross-fetch": "^3.1.5",
         "form-data": "^4.0.0",
diff --git a/package.json b/package.json
index e6eb8be..8e26ed3 100644
--- a/package.json
+++ b/package.json
@@ -35,7 +35,7 @@
     "topola": "^3.6.1",
     "turbocommons-ts": "^3.8.0",
     "unified": "^10.1.0",
-    "wikitree-js": "^0.1.0"
+    "wikitree-js": "^0.4.0"
   },
   "devDependencies": {
     "@types/array.prototype.flatmap": "^1.2.2",
diff --git a/src/datasource/wikitree.ts b/src/datasource/wikitree.ts
index 55d93f8..ece68c5 100644
--- a/src/datasource/wikitree.ts
+++ b/src/datasource/wikitree.ts
@@ -23,6 +23,8 @@ import {
   Person,
 } from 'wikitree-js';
 
+const WIKITREE_APP_ID = 'topola-viewer';
+
 /** Prefix for IDs of private individuals. */
 export const PRIVATE_ID_PREFIX = '~Private';
 
@@ -46,12 +48,15 @@ function setSessionStorageItem(key: string, value: string) {
 }
 
 function getApiOptions(handleCors: boolean) {
-  return handleCors
-    ? {
-        apiUrl:
-          'https://topola-cors-server.up.railway.app/https://api.wikitree.com/api.php',
-      }
-    : {};
+  return Object.assign(
+    {appId: WIKITREE_APP_ID},
+    handleCors
+      ? {
+          apiUrl:
+            'https://topola-cors-server.up.railway.app/https://api.wikitree.com/api.php',
+        }
+      : {},
+  );
 }
 
 /**
@@ -128,7 +133,7 @@ export async function loadWikiTree(
   const handleCors = window.location.hostname !== 'apps.wikitree.com';
 
   if (!handleCors && !getLoggedInUserName() && authcode) {
-    const loginResult = await clientLogin(authcode);
+    const loginResult = await clientLogin(authcode, {appId: WIKITREE_APP_ID});
     if (loginResult.result === 'Success') {
       sessionStorage.clear();
     }
@@ -826,4 +831,3 @@ export class WikiTreeDataSource implements DataSource<WikiTreeSourceSpec> {
     }
   }
 }
-