diff --git a/src/models/api_key.js b/src/models/api_key.ts
similarity index 82%
rename from src/models/api_key.js
rename to src/models/api_key.ts
index 1ceff1ea2..1898f52ee 100644
--- a/src/models/api_key.js
+++ b/src/models/api_key.ts
@@ -6,6 +6,6 @@ import EasyPostObject from './easypost_object';
  * @extends EasyPostObject
  */
 export default class ApiKey extends EasyPostObject {
-  static active;
-  static key;
+  declare active?: boolean | null;
+  declare key?: string | null;
 }
diff --git a/src/models/brand.js b/src/models/brand.ts
similarity index 50%
rename from src/models/brand.js
rename to src/models/brand.ts
index 585f27f43..0d19e9671 100644
--- a/src/models/brand.js
+++ b/src/models/brand.ts
@@ -6,13 +6,12 @@ import EasyPostObject from './easypost_object';
  * @extends EasyPostObject
  */
 export default class Brand extends EasyPostObject {
-  static ad_href;
-  static ad;
-  static background_color;
-  static color;
-  static logo_href;
-  static logo;
-  static name;
-  static theme;
-  static user_id;
+  declare ad_href?: string | null;
+  declare ad?: string | null;
+  declare background_color?: string | null;
+  declare color?: string | null;
+  declare logo_href?: string | null;
+  declare logo?: string | null;
+  declare theme?: 'theme1' | 'theme2' | null;
+  declare user_id?: string | null;
 }
diff --git a/src/models/end_shipper.js b/src/models/end_shipper.ts
similarity index 52%
rename from src/models/end_shipper.js
rename to src/models/end_shipper.ts
index 4caad0508..111f24b1b 100644
--- a/src/models/end_shipper.js
+++ b/src/models/end_shipper.ts
@@ -6,14 +6,14 @@ import EasyPostObject from './easypost_object';
  * @extends EasyPostObject
  */
 export default class EndShipper extends EasyPostObject {
-  static street1;
-  static street2;
-  static city;
-  static state;
-  static zip;
-  static country;
-  static name;
-  static company;
-  static phone;
-  static email;
+  declare street1?: string | null;
+  declare street2?: string | null;
+  declare city?: string | null;
+  declare state?: string | null;
+  declare zip?: string | null;
+  declare country?: string | null;
+  declare name?: string | null;
+  declare company?: string | null;
+  declare phone?: string | null;
+  declare email?: string | null;
 }
diff --git a/src/models/form.js b/src/models/form.ts
similarity index 51%
rename from src/models/form.js
rename to src/models/form.ts
index a80030bc8..60771c0a3 100644
--- a/src/models/form.js
+++ b/src/models/form.ts
@@ -6,7 +6,16 @@ import EasyPostObject from './easypost_object';
  * @extends EasyPostObject
  */
 export default class Form extends EasyPostObject {
-  static form_type;
-  static form_url;
-  static submitted_electronically;
+  declare form_type?:
+    | 'cn22'
+    | 'cod_return_label'
+    | 'commercial_invoice'
+    | 'high_value_report'
+    | 'label_qr_code'
+    | 'nafta_certificate_of_origin'
+    | 'order_summary'
+    | 'return_packing_slip'
+    | 'rma_qr_code';
+  declare form_url?: string | null;
+  declare submitted_electronically?: boolean | null;
 }
diff --git a/src/models/report.js b/src/models/report.ts
similarity index 50%
rename from src/models/report.js
rename to src/models/report.ts
index f8d38bbff..e57237837 100644
--- a/src/models/report.js
+++ b/src/models/report.ts
@@ -6,11 +6,11 @@ import EasyPostObject from './easypost_object';
  * @extends EasyPostObject
  */
 export default class Report extends EasyPostObject {
-  static end_date;
-  static include_children;
-  static send_email;
-  static start_date;
-  static status;
-  static url_expires_at;
-  static url;
+  declare end_date?: string | null;
+  declare include_children?: boolean | null;
+  declare send_email?: boolean | null;
+  declare start_date?: string | null;
+  declare status?: 'new' | 'available' | 'failed' | null;
+  declare url_expires_at?: string | null;
+  declare url?: string | null;
 }
diff --git a/src/models/user.js b/src/models/user.js
deleted file mode 100644
index 0a32af626..000000000
--- a/src/models/user.js
+++ /dev/null
@@ -1,22 +0,0 @@
-import EasyPostObject from './easypost_object';
-
-/**
- * A {@link https://docs.easypost.com/docs/users ApiKey} represents an EasyPost account or child account.
- * @public
- * @extends EasyPostObject
- */
-export default class User extends EasyPostObject {
-  static api_keys;
-  static balance;
-  static cc_fee_rate;
-  static children;
-  static email;
-  static insurance_fee_minimum;
-  static insurance_fee_rate;
-  static name;
-  static parent_id;
-  static phone_number;
-  static price_per_shipment;
-  static recharge_amount;
-  static secondary_recharge_amount;
-}
diff --git a/src/models/user.ts b/src/models/user.ts
new file mode 100644
index 000000000..f20d1e41d
--- /dev/null
+++ b/src/models/user.ts
@@ -0,0 +1,23 @@
+import EasyPostObject from './easypost_object';
+
+/**
+ * A {@link https://docs.easypost.com/docs/users ApiKey} represents an EasyPost account or child account.
+ * @public
+ * @extends EasyPostObject
+ */
+export default class User extends EasyPostObject {
+  declare api_keys?: Record<string, unknown>[] | null;
+  declare balance?: string | null;
+  declare cc_fee_rate?: string | null;
+  declare children?: Record<string, unknown>[] | null;
+  declare email?: string | null;
+  declare insurance_fee_minimum?: string | null;
+  declare insurance_fee_rate?: string | null;
+  declare name?: string | null;
+  declare parent_id?: string | null;
+  declare phone_number?: string | null;
+  declare price_per_shipment?: string | null;
+  declare recharge_amount?: string | null;
+  declare recharge_threshold?: string | null;
+  declare secondary_recharge_amount?: string | null;
+}