diff --git a/package.json b/package.json
index 736aebf..317aed1 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,8 @@
     "dev": "tsx watch src/index.ts",
     "build": "prisma generate && tsc",
     "start": "prisma migrate deploy && node dist/index.js",
-    "prisma:migrate": "prisma migrate dev"
+    "prisma:migrate": "prisma migrate dev",
+    "seed:demo": "tsx scripts/seed-demo.ts"
   },
   "dependencies": {
     "@fastify/cors": "^11.2.0",
diff --git a/scripts/seed-demo.ts b/scripts/seed-demo.ts
new file mode 100644
index 0000000..1b6478b
--- /dev/null
+++ b/scripts/seed-demo.ts
@@ -0,0 +1,73 @@
+import { prisma } from '../src/db.js'
+
+function requiredEnv(name: string): string {
+  const value = process.env[name]?.trim()
+  if (!value) throw new Error(`${name} is required`)
+  return value
+}
+
+const logtoId = requiredEnv('DEMO_LOGTO_USER_ID')
+const accountUuid = '99999999-1111-4111-8111-111111111111'
+const serviceAccountUuid = '99999999-2222-4111-8111-111111111111'
+
+await prisma.account.upsert({
+  where: { uuid: accountUuid },
+  create: {
+    uuid: accountUuid,
+    name: `Demo user ${logtoId}`,
+    accountType: 'USER',
+    description: 'Demo seed user account',
+  },
+  update: {
+    name: `Demo user ${logtoId}`,
+    accountType: 'USER',
+    description: 'Demo seed user account',
+  },
+})
+
+await prisma.account.upsert({
+  where: { uuid: serviceAccountUuid },
+  create: {
+    uuid: serviceAccountUuid,
+    name: 'Demo logistics service',
+    accountType: 'SERVICE',
+    description: 'Demo seed service account',
+    serviceInfo: {
+      create: { slug: 'demo-logistics' },
+    },
+  },
+  update: {
+    name: 'Demo logistics service',
+    accountType: 'SERVICE',
+    description: 'Demo seed service account',
+  },
+})
+
+await prisma.serviceAccount.upsert({
+  where: { slug: 'demo-logistics' },
+  create: {
+    slug: 'demo-logistics',
+    accountUuid: serviceAccountUuid,
+  },
+  update: {
+    accountUuid: serviceAccountUuid,
+  },
+})
+
+const operations = [
+  { code: 1001, name: 'demo.order.created', description: 'Demo order created' },
+  { code: 1002, name: 'demo.order.paid', description: 'Demo order paid' },
+  { code: 1003, name: 'demo.order.delivered', description: 'Demo order delivered' },
+]
+
+for (const operation of operations) {
+  await prisma.operationCode.upsert({
+    where: { code: operation.code },
+    create: operation,
+    update: operation,
+  })
+}
+
+console.log(`Seeded billing demo data for ${logtoId}`)
+
+await prisma.$disconnect()