diff --git a/src/models/batch.js b/src/models/batch.js
deleted file mode 100644
index 8b5534e90..000000000
--- a/src/models/batch.js
+++ /dev/null
@@ -1,17 +0,0 @@
-import EasyPostObject from './easypost_object';
-
-/**
- * A {@link https://docs.easypost.com/docs/batches Batch} represents a collection of {@link Shipment shipments} that can be processed together.
- * @public
- * @extends EasyPostObject
- */
-export default class Batch extends EasyPostObject {
-  static label_url;
-  static num_shipments;
-  static pickup;
-  static reference;
-  static scan_form;
-  static shipments;
-  static state;
-  static status;
-}
diff --git a/src/models/batch.ts b/src/models/batch.ts
new file mode 100644
index 000000000..7888b9ea6
--- /dev/null
+++ b/src/models/batch.ts
@@ -0,0 +1,17 @@
+import EasyPostObject from './easypost_object';
+
+/**
+ * A {@link https://docs.easypost.com/docs/batches Batch} represents a collection of {@link Shipment shipments} that can be processed together.
+ * @public
+ * @extends EasyPostObject
+ */
+export default class Batch extends EasyPostObject {
+  declare label_url?: string | null;
+  declare num_shipments?: number | null;
+  declare pickup?: Record<string, unknown> | null;
+  declare reference?: string | null;
+  declare scan_form?: Record<string, unknown> | null;
+  declare shipments?: Record<string, unknown>[] | null;
+  declare state?: string | null;
+  declare status?: Record<string, number> | null;
+}
diff --git a/src/models/order.js b/src/models/order.js
deleted file mode 100644
index 476583001..000000000
--- a/src/models/order.js
+++ /dev/null
@@ -1,33 +0,0 @@
-import Constants from '../constants';
-import EasyPostObject from './easypost_object';
-
-/**
- * An {@link https://docs.easypost.com/docs/orders Order} represents a collection of packages, intended only for multi-parcel shipments.
- * @public
- * @extends EasyPostObject
- */
-export default class Order extends EasyPostObject {
-  static buyer_address;
-  static from_address;
-  static is_return;
-  static messages;
-  static rates;
-  static reference;
-  static return_address;
-  static shipments;
-  static to_address;
-
-  /**
-   * Get the lowest rate for this {@link Order}.
-   * @public
-   * @param {string[]} [carriers] - List of allowed carriers to filter by
-   * @param {string[]} [services] - List of allowed services to filter by
-   * @returns {Rate} - The lowest rate
-   * @throws {FilteringError} - If no applicable rates are found
-   */
-  lowestRate(carriers, services) {
-    const rates = this.rates || [];
-
-    return Constants.Utils.getLowestRate(rates, carriers, services);
-  }
-}
diff --git a/src/models/order.ts b/src/models/order.ts
new file mode 100644
index 000000000..57767bc37
--- /dev/null
+++ b/src/models/order.ts
@@ -0,0 +1,38 @@
+import Constants from '../constants';
+import EasyPostObject from './easypost_object';
+
+/**
+ * An {@link https://docs.easypost.com/docs/orders Order} represents a collection of packages, intended only for multi-parcel shipments.
+ * @public
+ * @extends EasyPostObject
+ */
+export default class Order extends EasyPostObject {
+  declare buyer_address?: Record<string, unknown> | null;
+  declare from_address?: Record<string, unknown> | null;
+  declare is_return?: boolean | null;
+  declare messages?: Record<string, unknown>[] | null;
+  declare rates?: Parameters<typeof Constants.Utils.getLowestRate>[0] | null;
+  declare reference?: string | null;
+  declare return_address?: Record<string, unknown> | null;
+  declare shipments?: Record<string, unknown>[] | null;
+  declare to_address?: Record<string, unknown> | null;
+
+  /**
+   * Get the lowest rate for this {@link Order}.
+   * @public
+   * @param {string[]} [carriers] - List of allowed carriers to filter by
+   * @param {string[]} [services] - List of allowed services to filter by
+   * @returns {Rate} - The lowest rate
+   * @throws {FilteringError} - If no applicable rates are found
+   */
+  lowestRate(
+    carriers?: string[],
+    services?: string[],
+  ): ReturnType<typeof Constants.Utils.getLowestRate> {
+    const rates = ((this as Order & { rates?: unknown[] }).rates || []) as Parameters<
+      typeof Constants.Utils.getLowestRate
+    >[0];
+
+    return Constants.Utils.getLowestRate(rates, carriers, services);
+  }
+}
diff --git a/src/models/pickup.js b/src/models/pickup.js
deleted file mode 100644
index c5087a17c..000000000
--- a/src/models/pickup.js
+++ /dev/null
@@ -1,36 +0,0 @@
-import Constants from '../constants';
-import EasyPostObject from './easypost_object';
-
-/**
- * A {@link https://docs.easypost.com/docs/pickups Pickup} represents a scheduled carrier pickup of packages from an {@link https://docs.easypost.com/docs/addresses Address}.
- * @public
- * @extends EasyPostObject
- */
-export default class Pickup extends EasyPostObject {
-  static address;
-  static carrier_accounts;
-  static confirmation;
-  static instructions;
-  static is_account_address;
-  static max_datetime;
-  static messages;
-  static min_datetime;
-  static pickup_rates;
-  static reference;
-  static shipment;
-  static status;
-
-  /**
-   * Get the lowest rate for this {@link Pickup}.
-   * @public
-   * @param {string[]} [carriers] - List of allowed carriers to filter by
-   * @param {string[]} [services] - List of allowed services to filter by
-   * @returns {Rate} - The lowest rate
-   * @throws {FilteringError} - If no applicable rates are found
-   */
-  lowestRate(carriers, services) {
-    const rates = this.pickup_rates || [];
-
-    return Constants.Utils.getLowestRate(rates, carriers, services);
-  }
-}
diff --git a/src/models/pickup.ts b/src/models/pickup.ts
new file mode 100644
index 000000000..f1e46b70b
--- /dev/null
+++ b/src/models/pickup.ts
@@ -0,0 +1,40 @@
+import Constants from '../constants';
+import EasyPostObject from './easypost_object';
+
+/**
+ * A {@link https://docs.easypost.com/docs/pickups Pickup} represents a scheduled carrier pickup of packages from an {@link https://docs.easypost.com/docs/addresses Address}.
+ * @public
+ * @extends EasyPostObject
+ */
+export default class Pickup extends EasyPostObject {
+  declare address?: Record<string, unknown> | null;
+  declare carrier_accounts?: Record<string, unknown>[] | null;
+  declare confirmation?: string | null;
+  declare instructions?: string | null;
+  declare is_account_address?: boolean | null;
+  declare max_datetime?: string | null;
+  declare messages?: Record<string, unknown>[] | null;
+  declare min_datetime?: string | null;
+  declare pickup_rates?: Parameters<typeof Constants.Utils.getLowestRate>[0] | null;
+  declare reference?: string | null;
+  declare shipment?: Record<string, unknown> | null;
+  declare status?: 'unknown' | 'scheduled' | 'canceled' | null;
+
+  /**
+   * Get the lowest rate for this {@link Pickup}.
+   * @public
+   * @param {string[]} [carriers] - List of allowed carriers to filter by
+   * @param {string[]} [services] - List of allowed services to filter by
+   * @returns {Rate} - The lowest rate
+   * @throws {FilteringError} - If no applicable rates are found
+   */
+  lowestRate(
+    carriers?: string[],
+    services?: string[],
+  ): ReturnType<typeof Constants.Utils.getLowestRate> {
+    const rates = ((this as Pickup & { pickup_rates?: unknown[] }).pickup_rates ||
+      []) as Parameters<typeof Constants.Utils.getLowestRate>[0];
+
+    return Constants.Utils.getLowestRate(rates, carriers, services);
+  }
+}
diff --git a/src/models/pickup_rate.js b/src/models/pickup_rate.ts
similarity index 57%
rename from src/models/pickup_rate.js
rename to src/models/pickup_rate.ts
index 4e52d5765..7e94394ff 100644
--- a/src/models/pickup_rate.js
+++ b/src/models/pickup_rate.ts
@@ -6,9 +6,9 @@ import EasyPostObject from './easypost_object';
  * @extends EasyPostObject
  */
 export default class PickupRate extends EasyPostObject {
-  static carrier;
-  static currency;
-  static pickup_id;
-  static rate;
-  static service;
+  declare carrier?: string | null;
+  declare currency?: string | null;
+  declare pickup_id?: string | null;
+  declare rate?: string | null;
+  declare service?: string | null;
 }
diff --git a/src/models/rate.js b/src/models/rate.js
deleted file mode 100644
index 2b757f9e4..000000000
--- a/src/models/rate.js
+++ /dev/null
@@ -1,24 +0,0 @@
-import EasyPostObject from './easypost_object';
-
-/**
- * A {@link https://docs.easypost.com/docs/shipments/rates Rate} represents pricing information for shipping a specific {@link Parcel} with a specific carrier and service level.
- * @public
- * @extends EasyPostObject
- */
-export default class Rate extends EasyPostObject {
-  static billing_type;
-  static carrier_account_id;
-  static carrier;
-  static currency;
-  static delivery_date_guaranteed;
-  static delivery_date;
-  static delivery_days;
-  static est_delivery_days;
-  static list_currency;
-  static list_rate;
-  static rate;
-  static retail_currency;
-  static retail_rate;
-  static service;
-  static shipment_id;
-}
diff --git a/src/models/rate.ts b/src/models/rate.ts
new file mode 100644
index 000000000..85707d487
--- /dev/null
+++ b/src/models/rate.ts
@@ -0,0 +1,24 @@
+import EasyPostObject from './easypost_object';
+
+/**
+ * A {@link https://docs.easypost.com/docs/shipments/rates Rate} represents pricing information for shipping a specific {@link Parcel} with a specific carrier and service level.
+ * @public
+ * @extends EasyPostObject
+ */
+export default class Rate extends EasyPostObject {
+  declare billing_type?: string | null;
+  declare carrier_account_id?: string | null;
+  declare carrier?: string | null;
+  declare currency?: string | null;
+  declare delivery_date_guaranteed?: boolean | null;
+  declare delivery_date?: string | null;
+  declare delivery_days?: number | null;
+  declare est_delivery_days?: number | null;
+  declare list_currency?: string | null;
+  declare list_rate?: string | null;
+  declare rate?: string | null;
+  declare retail_currency?: string | null;
+  declare retail_rate?: string | null;
+  declare service?: string | null;
+  declare shipment_id?: string | null;
+}
diff --git a/src/models/refund.js b/src/models/refund.ts
similarity index 52%
rename from src/models/refund.js
rename to src/models/refund.ts
index dab7c280d..38c234f3c 100644
--- a/src/models/refund.js
+++ b/src/models/refund.ts
@@ -6,9 +6,9 @@ import EasyPostObject from './easypost_object';
  * @extends EasyPostObject
  */
 export default class Refund extends EasyPostObject {
-  static carrier;
-  static confirmation_number;
-  static shipment_id;
-  static status;
-  static tracking_code;
+  declare carrier?: string | null;
+  declare confirmation_number?: string | null;
+  declare shipment_id?: string | null;
+  declare status?: 'submitted' | 'refunded' | 'rejected' | null;
+  declare tracking_code?: string | null;
 }
diff --git a/src/models/scan_form.js b/src/models/scan_form.ts
similarity index 52%
rename from src/models/scan_form.js
rename to src/models/scan_form.ts
index b4e7d4312..4c63ecd2f 100644
--- a/src/models/scan_form.js
+++ b/src/models/scan_form.ts
@@ -6,11 +6,11 @@ import EasyPostObject from './easypost_object';
  * @extends EasyPostObject
  */
 export default class ScanForm extends EasyPostObject {
-  static address;
-  static batch_id;
-  static form_file_type;
-  static form_url;
-  static message;
-  static status;
-  static tracking_codes;
+  declare address?: Record<string, unknown> | null;
+  declare batch_id?: string | null;
+  declare form_file_type?: string | null;
+  declare form_url?: string | null;
+  declare message?: string | null;
+  declare status?: 'creating' | 'created' | 'failed' | null;
+  declare tracking_codes?: string[] | null;
 }