diff --git a/js/testapps/anthropic/package.json b/js/testapps/anthropic/package.json
index 08e1a0d2fd..fd54741017 100644
--- a/js/testapps/anthropic/package.json
+++ b/js/testapps/anthropic/package.json
@@ -10,6 +10,7 @@
     "start:beta": "node lib/beta/basic.js",
     "dev:stable": "genkit start -- npx tsx --watch src/stable/basic.ts",
     "dev:beta": "genkit start -- npx tsx --watch src/beta/basic.ts",
+    "dev:beta:structured-output": "genkit start -- npx tsx --watch src/beta/structured_output.ts",
     "dev:stable:text-plain": "genkit start -- npx tsx --watch src/stable/text-plain.ts",
     "dev:stable:webp": "genkit start -- npx tsx --watch src/stable/webp.ts",
     "dev:stable:pdf": "genkit start -- npx tsx --watch src/stable/pdf.ts",
diff --git a/js/testapps/anthropic/src/beta/structured_output.ts b/js/testapps/anthropic/src/beta/structured_output.ts
new file mode 100644
index 0000000000..725c9a0681
--- /dev/null
+++ b/js/testapps/anthropic/src/beta/structured_output.ts
@@ -0,0 +1,85 @@
+/**
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { anthropic } from '@genkit-ai/anthropic';
+import { genkit, z } from 'genkit';
+
+const ai = genkit({
+  plugins: [
+    // Default all flows in this sample to the beta surface
+    anthropic({
+      apiVersion: 'beta',
+      cacheSystemPrompt: true,
+      apiKey: process.env.ANTHROPIC_API_KEY,
+    }),
+  ],
+});
+
+const betaSonnet = anthropic.model('claude-sonnet-4-5', { apiVersion: 'beta' });
+
+ai.defineFlow('anthropic-beta-generate-person-json', async () => {
+  const { text } = await ai.generate({
+    model: betaSonnet,
+    prompt:
+      'Generate a fictional person with a random name, random age, and random city.',
+    config: { temperature: 0.6 },
+    output: {
+      schema: z.object({
+        name: z.string(),
+        age: z.number(),
+        city: z.string(),
+      }),
+      format: 'json',
+      constrained: true,
+    },
+  });
+
+  return text;
+});
+
+ai.defineFlow(
+  'anthropic-beta-generate-person-json-stream',
+  async (_, { sendChunk }) => {
+    const { stream } = ai.generateStream({
+      model: betaSonnet,
+      prompt: [
+        {
+          text: 'Generate a fictional person with a random name, random age, and random city.',
+        },
+      ],
+      config: { temperature: 0.6 },
+      output: {
+        schema: z.object({
+          name: z.string(),
+          age: z.number(),
+          city: z.string(),
+        }),
+        format: 'json',
+        constrained: true,
+      },
+    });
+
+    const collected: string[] = [];
+    for await (const chunk of stream) {
+      if (chunk.text) {
+        collected.push(chunk.text);
+        sendChunk(chunk.text);
+      }
+    }
+
+    return collected.join('');
+  }
+);