diff --git a/bun.lock b/bun.lock
index 08b80f8..8bb0b1d 100644
--- a/bun.lock
+++ b/bun.lock
@@ -84,6 +84,7 @@
       "version": "0.0.1",
       "dependencies": {
         "@orpc/contract": "^1.13.2",
+        "@simplewebauthn/types": "^12.0.0",
         "libphonenumber-js": "^1.12.33",
         "zod": "^4.3.5",
       },
@@ -351,6 +352,8 @@
 
     "@rollup/rollup-win32-x64-msvc": ["@rollup/rollup-win32-x64-msvc@4.55.1", "", { "os": "win32", "cpu": "x64" }, "sha512-SPEpaL6DX4rmcXtnhdrQYgzQ5W2uW3SCJch88lB2zImhJRhIIK44fkUrgIV/Q8yUNfw5oyZ5vkeQsZLhCb06lw=="],
 
+    "@simplewebauthn/types": ["@simplewebauthn/types@12.0.0", "", {}, "sha512-q6y8MkoV8V8jB4zzp18Uyj2I7oFp2/ONL8c3j8uT06AOWu3cIChc1au71QYHrP2b+xDapkGTiv+9lX7xkTlAsA=="],
+
     "@standard-schema/spec": ["@standard-schema/spec@1.1.0", "", {}, "sha512-l2aFy5jALhniG5HgqrD6jXLi/rUWrKvqN/qJx6yoJsgKhblVd+iqqU4RCXavm/jPityDo5TCvKMnpjKnOriy0w=="],
 
     "@stricli/core": ["@stricli/core@1.2.5", "", {}, "sha512-+afyztQW7fwWkqmU2WQZbdc3LjnZThWYdtE0l+hykZ1Rvy7YGxZSvsVCS/wZ/2BNv117pQ9TU1GZZRIcPnB4tw=="],
diff --git a/packages/api-contract/package.json b/packages/api-contract/package.json
index 2f21ce3..427b28d 100644
--- a/packages/api-contract/package.json
+++ b/packages/api-contract/package.json
@@ -17,6 +17,7 @@
   },
   "dependencies": {
     "@orpc/contract": "^1.13.2",
+    "@simplewebauthn/types": "^12.0.0",
     "libphonenumber-js": "^1.12.33",
     "zod": "^4.3.5"
   },
diff --git a/packages/api-contract/src/contract.ts b/packages/api-contract/src/contract.ts
index 28e32ea..11362fc 100644
--- a/packages/api-contract/src/contract.ts
+++ b/packages/api-contract/src/contract.ts
@@ -1,3 +1,9 @@
+import type {
+  AuthenticationResponseJSON,
+  PublicKeyCredentialCreationOptionsJSON,
+  PublicKeyCredentialRequestOptionsJSON,
+  RegistrationResponseJSON,
+} from "@simplewebauthn/types";
 import { oc } from "@orpc/contract";
 import * as z from "zod";
 import {
@@ -72,28 +78,28 @@ export const contract = oc.router({
         .output(
           z.object({
             challengeId: z.number(),
-            options: z.any(), // PublicKeyCredentialCreationOptionsJSON
+            options: z.custom<PublicKeyCredentialCreationOptionsJSON>(),
           }),
         ),
       verifyRegistration: oc
         .input(
           z.object({
             challengeId: z.number(),
-            response: z.any(), // RegistrationResponseJSON
+            response: z.custom<RegistrationResponseJSON>(),
           }),
         )
         .output(z.void()),
       createAuthenticationOptions: oc.output(
         z.object({
           challengeId: z.number(),
-          options: z.any(), // PublicKeyCredentialRequestOptionsJSON
+          options: z.custom<PublicKeyCredentialRequestOptionsJSON>(),
         }),
       ),
       verifyAuthentication: oc
         .input(
           z.object({
             challengeId: z.number(),
-            response: z.any(), // AuthenticationResponseJSON
+            response: z.custom<AuthenticationResponseJSON>(),
           }),
         )
         .output(z.void()),
@@ -113,7 +119,7 @@ export const contract = oc.router({
     createPasskey: oc.input(z.object({ name: z.string() })).output(
       z.object({
         challengeId: z.number(),
-        options: z.any(), // PublicKeyCredentialCreationOptionsJSON
+        options: z.custom<PublicKeyCredentialCreationOptionsJSON>(),
       }),
     ),
     renamePasskey: oc
diff --git a/packages/api-contract/src/schemas/auth.ts b/packages/api-contract/src/schemas/auth.ts
index ba45015..c7139ca 100644
--- a/packages/api-contract/src/schemas/auth.ts
+++ b/packages/api-contract/src/schemas/auth.ts
@@ -1,3 +1,4 @@
+import type { RegistrationResponseJSON } from "@simplewebauthn/types";
 import * as z from "zod";
 import { emailSchema } from "./common.js";
 
@@ -8,7 +9,7 @@ import { emailSchema } from "./common.js";
  */
 export const passkeyInfoSchema = z.object({
   challengeId: z.number(),
-  response: z.any(), // RegistrationResponseJSON from @simplewebauthn/browser
+  response: z.custom<RegistrationResponseJSON>(),
 });
 
 /**