diff --git a/package.json b/package.json
index 37a8fac..d7344c2 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,19 @@
     "version": "1.7.0",
     "description": "Comprehensive NodeJS API wrapper for the Robinhood API",
     "main": "src/robinhood.js",
-    "typings": "robinhood.d.ts",
+    "typings": "types/robinhood.d.ts",
+    "typesVersions": {
+        "<4.1": {
+            "promises": [
+                "types/promises.v3.d.ts"
+            ]
+        },
+        ">=4.1": {
+            "promises": [
+                "types/promises.d.ts"
+            ]
+        }
+    },
     "exports": {
         ".": "./src/robinhood.js",
         "./promises": "./src/promises.js",
diff --git a/robinhood.d.ts b/robinhood.d.ts
deleted file mode 100644
index 8f025a0..0000000
--- a/robinhood.d.ts
+++ /dev/null
@@ -1,254 +0,0 @@
-import request = require('request')
-
-declare function robinhood(options: robinhood.Options.WebApiOpts, callback: robinhood.InitCallback): robinhood.RobinhoodWebApi;
-
-declare namespace robinhood {
-
-  export namespace Options {
-    interface WebApiOpts {
-      username?: string
-      password?: string
-      token?: string
-    }
-
-    interface OrdersOptions {
-      updated_at: string
-      instrument: string
-    }
-
-    interface EarningsOptionsWithSymbol {
-      range?: number
-      symbol: string
-    }
-
-    interface EarningsOptionsWithInstrument {
-      range?: number
-      instrument: string
-    }
-
-    interface BuySellOptions {
-      type: OrderType
-      quantity: number
-      bid_price: number
-      instrument: {
-        url?: string
-        symbol?: string
-      }
-      trigger: TriggerType
-      time: TimeInForceType
-    }
-  }
-
-  export type TagType = TagTypes
-  export type OrderType = OrderTypes
-  export type IntervalType = IntervalTypes
-  export type SpanType = SpanTypes
-  export type TriggerType = TriggerTypes
-  export type TimeInForceType = TimeInForceTypes
-  export type InitCallback = () => void
-
-  export type TagTypes =
-    '10-most-popular'
-    | '100-most-popular'
-    ;
-
-  export type TriggerTypes =
-    'immediate'
-    | 'day'
-    ;
-
-  export type TimeInForceTypes =
-    'gfd'
-    | 'gtc'
-    | 'oco'
-    ;
-
-  export type OrderTypes =
-    'limit'
-    | 'market'
-    ;
-
-  export type IntervalTypes =
-    '5minute'
-    | '10minute'
-    ;
-
-  export type SpanTypes =
-    'week'
-    | 'day'
-    ;
-
-
-  export interface RobinhoodWebApi {
-    /**
-     * Revokes the current token for this session.
-     * @param callback
-     */
-    expire_token (callback: request.RequestCallback): void
-
-    /**
-     * Returns the token for the current session.
-     */
-    auth_token (): string|null
-
-    /**
-     * Get the current user's investment profile.
-     * @param callback
-     */
-    investment_profile (callback: request.RequestCallback): void
-
-    /**
-     * Return all instruments, or those for a given symbol.
-     * @param callback
-     */
-    instruments(callback: request.RequestCallback): void
-    instruments(symbol: string, callback: request.RequestCallback): void
-
-    /**
-     * Get fundamental data about a symbol.
-     * @param symbol
-     * @param callback
-     */
-    fundamentals (symbol: string, callback: request.RequestCallback): void
-
-    /**
-     * Get the popularity for a specified stock.
-     * @param symbol
-     * @param callback
-     */
-    popularity (symbol: string, callback: request.RequestCallback): void
-
-    /**
-     * Returns account information for the current user session.
-     * @param callback
-     */
-    accounts (callback: request.RequestCallback): void
-
-    /**
-     * Get the user's quote data for a specified stock.
-     * @param symbol
-     * @param callback
-     */
-    quote_data (symbol: string, callback: request.RequestCallback): void
-    quote_data (symbol: string[], callback: request.RequestCallback): void
-
-    /**
-     * Get the user's order information for the given options or specific order.
-     * @param options
-     * @param callback
-     */
-    orders (options: Options.OrdersOptions, callback: request.RequestCallback): void
-    orders (orderId: string, callback: request.RequestCallback): void
-
-    /**
-     * Get the user's position information.
-     * @param callback
-     */
-    positions (callback: request.RequestCallback): void
-
-    /**
-     * Get the user's nonzero position information only.
-     * @param callback
-     */
-    nonzero_positions (callback: request.RequestCallback): void
-
-    /**
-     * Place a buy order on a specified stock.
-     * @param options
-     * @param callback
-     */
-    place_buy_order (options: Options.BuySellOptions, callback: request.RequestCallback): void
-
-    /**
-     * Place a sell order on a specified stock.
-     * @param options
-     * @param callback
-     */
-    place_sell_order (options: Options.BuySellOptions, callback: request.RequestCallback): void
-
-    /**
-     * Cancel an order with the order object or order ID.
-     * @param order
-     * @param callback
-     */
-    cancel_order (order: object, callback: request.RequestCallback): void
-    cancel_order (orderId: string, callback: request.RequestCallback): void
-
-    /**
-     * Get historical information for the given symbol.
-     * @param symbol
-     * @param intv
-     * @param span
-     * @param callback
-     */
-    historicals (symbol: string, intv: IntervalType, span: SpanType, callback: request.RequestCallback): void
-
-    /**
-     * Get user information.
-     * @param callback
-     */
-    user (callback: request.RequestCallback): void
-
-    /**
-     * Returns the user's watchlists
-     * @param callback
-     */
-    watchlists (callback: request.RequestCallback): void
-
-    /**
-     * Get the earnings information using either the symbol or instrument.
-     * @param options
-     * @param callback
-     */
-    earnings (options: Options.EarningsOptionsWithInstrument|Options.EarningsOptionsWithSymbol, callback: request.RequestCallback): void
-
-    /**
-     * Get the user's dividends information.
-     * @param callback
-     */
-    dividends (callback: request.RequestCallback): void
-
-    /**
-     * Fetch splits for the given instrument.
-     * @param instrument
-     * @param callback
-     */
-    splits (instrument: string, callback: request.RequestCallback): void
-
-    /**
-     * Returns news for a given symbol.
-     * @param symbol
-     * @param callback
-     */
-    news (symbol: string, callback: request.RequestCallback): void
-
-    /**
-     * Returns information for the given tag.
-     * Retrieve Robinhood's new Tags: In 2018, Robinhood Web will expose more
-     * Social and Informational tools. You'll see how popular a security is with
-     * other Robinhood users, MorningStar ratings, etc.
-     * @param tag
-     * @param callback
-     */
-    tag (tag: TagType, callback: request.RequestCallback): void
-
-    /**
-     * Perform a GET request against the given URL.
-     * Used to get continued or paginated data from the API. Queries with long
-     * results return a reference to the next set.
-     * @param url
-     * @param callback
-     */
-    url (url: string, callback: request.RequestCallback): void
-
-    /**
-     *
-     * @param callback
-     */
-    sp500_down (callback: request.RequestCallback): void
-
-    sp500_up (callback: request.RequestCallback): void
-  }
-}
-
-export = robinhood
diff --git a/types/promises.d.ts b/types/promises.d.ts
new file mode 100644
index 0000000..f190333
--- /dev/null
+++ b/types/promises.d.ts
@@ -0,0 +1,42 @@
+// requires typescript 4.1+
+
+import robinhood = require("./robinhood");
+
+type RemoveFnParam<T extends unknown[]> = T extends []
+    ? []
+    : T extends [infer H, ...infer R]
+    ? H extends Function
+        ? RemoveFnParam<R>
+        : [H, ...RemoveFnParam<R>]
+    : T;
+
+type LastTupleElement<T extends unknown[]> = T extends [infer X]
+    ? X
+    : T extends [infer H, ...infer R]
+    ? LastTupleElement<R>
+    : T;
+
+declare function RobinhoodPromiseAPI(
+    options: robinhood.Options.WebApiOpts
+): Promise<
+    {
+        [key in keyof robinhood.RobinhoodWebApi]: (
+            ...args: RemoveFnParam<Parameters<robinhood.RobinhoodWebApi[key]>>
+        ) => Promise<
+            LastTupleElement<
+                Parameters<robinhood.RobinhoodWebApi[key]>
+            > extends Function
+                ? LastTupleElement<
+                      Parameters<
+                          // @ts-expect-error: this must be a function in this block
+                          LastTupleElement<
+                              Parameters<robinhood.RobinhoodWebApi[key]>
+                          >
+                      >
+                  >
+                : ReturnType<robinhood.RobinhoodWebApi[key]>
+        >;
+    }
+>;
+
+export = RobinhoodPromiseAPI;
diff --git a/types/promises.v3.d.ts b/types/promises.v3.d.ts
new file mode 100644
index 0000000..c67b533
--- /dev/null
+++ b/types/promises.v3.d.ts
@@ -0,0 +1,15 @@
+// for typescript <4.1
+
+import robinhood = require("./robinhood");
+
+declare function RobinhoodPromiseAPI(
+    options: robinhood.Options.WebApiOpts
+): Promise<
+    {
+        [key in keyof robinhood.RobinhoodWebApi]: (
+            ...args: any[]
+        ) => Promise<any>;
+    }
+>;
+
+export = RobinhoodPromiseAPI;
diff --git a/types/robinhood.d.ts b/types/robinhood.d.ts
new file mode 100644
index 0000000..99371b0
--- /dev/null
+++ b/types/robinhood.d.ts
@@ -0,0 +1,255 @@
+import request = require("request");
+
+declare function robinhood(
+    options: robinhood.Options.WebApiOpts,
+    callback: robinhood.InitCallback
+): robinhood.RobinhoodWebApi;
+
+declare namespace robinhood {
+    export namespace Options {
+        interface WebApiOpts {
+            username?: string;
+            password?: string;
+            token?: string;
+        }
+
+        interface OrdersOptions {
+            updated_at: string;
+            instrument: string;
+        }
+
+        interface EarningsOptionsWithSymbol {
+            range?: number;
+            symbol: string;
+        }
+
+        interface EarningsOptionsWithInstrument {
+            range?: number;
+            instrument: string;
+        }
+
+        interface BuySellOptions {
+            type: OrderType;
+            quantity: number;
+            bid_price: number;
+            instrument: {
+                url?: string;
+                symbol?: string;
+            };
+            trigger: TriggerType;
+            time: TimeInForceType;
+        }
+    }
+
+    export type TagType = TagTypes;
+    export type OrderType = OrderTypes;
+    export type IntervalType = IntervalTypes;
+    export type SpanType = SpanTypes;
+    export type TriggerType = TriggerTypes;
+    export type TimeInForceType = TimeInForceTypes;
+    export type InitCallback = () => void;
+
+    export type TagTypes = "10-most-popular" | "100-most-popular";
+
+    export type TriggerTypes = "immediate" | "day";
+
+    export type TimeInForceTypes = "gfd" | "gtc" | "oco";
+
+    export type OrderTypes = "limit" | "market";
+
+    export type IntervalTypes = "5minute" | "10minute";
+
+    export type SpanTypes = "week" | "day";
+
+    export interface RobinhoodWebApi {
+        /**
+         * Revokes the current token for this session.
+         * @param callback
+         */
+        expire_token(callback: request.RequestCallback): void;
+
+        /**
+         * Returns the token for the current session.
+         */
+        auth_token(): string | null;
+
+        /**
+         * Get the current user's investment profile.
+         * @param callback
+         */
+        investment_profile(callback: request.RequestCallback): void;
+
+        /**
+         * Return all instruments, or those for a given symbol.
+         * @param callback
+         */
+        instruments(callback: request.RequestCallback): void;
+        instruments(symbol: string, callback: request.RequestCallback): void;
+
+        /**
+         * Get fundamental data about a symbol.
+         * @param symbol
+         * @param callback
+         */
+        fundamentals(symbol: string, callback: request.RequestCallback): void;
+
+        /**
+         * Get the popularity for a specified stock.
+         * @param symbol
+         * @param callback
+         */
+        popularity(symbol: string, callback: request.RequestCallback): void;
+
+        /**
+         * Returns account information for the current user session.
+         * @param callback
+         */
+        accounts(callback: request.RequestCallback): void;
+
+        /**
+         * Get the user's quote data for a specified stock.
+         * @param symbol
+         * @param callback
+         */
+        quote_data(symbol: string, callback: request.RequestCallback): void;
+        quote_data(symbol: string[], callback: request.RequestCallback): void;
+
+        /**
+         * Get the user's order information for the given options or specific order.
+         * @param options
+         * @param callback
+         */
+        orders(
+            options: Options.OrdersOptions,
+            callback: request.RequestCallback
+        ): void;
+        orders(orderId: string, callback: request.RequestCallback): void;
+
+        /**
+         * Get the user's position information.
+         * @param callback
+         */
+        positions(callback: request.RequestCallback): void;
+
+        /**
+         * Get the user's nonzero position information only.
+         * @param callback
+         */
+        nonzero_positions(callback: request.RequestCallback): void;
+
+        /**
+         * Place a buy order on a specified stock.
+         * @param options
+         * @param callback
+         */
+        place_buy_order(
+            options: Options.BuySellOptions,
+            callback: request.RequestCallback
+        ): void;
+
+        /**
+         * Place a sell order on a specified stock.
+         * @param options
+         * @param callback
+         */
+        place_sell_order(
+            options: Options.BuySellOptions,
+            callback: request.RequestCallback
+        ): void;
+
+        /**
+         * Cancel an order with the order object or order ID.
+         * @param order
+         * @param callback
+         */
+        cancel_order(order: object, callback: request.RequestCallback): void;
+        cancel_order(orderId: string, callback: request.RequestCallback): void;
+
+        /**
+         * Get historical information for the given symbol.
+         * @param symbol
+         * @param intv
+         * @param span
+         * @param callback
+         */
+        historicals(
+            symbol: string,
+            intv: IntervalType,
+            span: SpanType,
+            callback: request.RequestCallback
+        ): void;
+
+        /**
+         * Get user information.
+         * @param callback
+         */
+        user(callback: request.RequestCallback): void;
+
+        /**
+         * Returns the user's watchlists
+         * @param callback
+         */
+        watchlists(callback: request.RequestCallback): void;
+
+        /**
+         * Get the earnings information using either the symbol or instrument.
+         * @param options
+         * @param callback
+         */
+        earnings(
+            options:
+                | Options.EarningsOptionsWithInstrument
+                | Options.EarningsOptionsWithSymbol,
+            callback: request.RequestCallback
+        ): void;
+
+        /**
+         * Get the user's dividends information.
+         * @param callback
+         */
+        dividends(callback: request.RequestCallback): void;
+
+        /**
+         * Fetch splits for the given instrument.
+         * @param instrument
+         * @param callback
+         */
+        splits(instrument: string, callback: request.RequestCallback): void;
+
+        /**
+         * Returns news for a given symbol.
+         * @param symbol
+         * @param callback
+         */
+        news(symbol: string, callback: request.RequestCallback): void;
+
+        /**
+         * Returns information for the given tag.
+         * Retrieve Robinhood's new Tags: In 2018, Robinhood Web will expose more
+         * Social and Informational tools. You'll see how popular a security is with
+         * other Robinhood users, MorningStar ratings, etc.
+         * @param tag
+         * @param callback
+         */
+        tag(tag: TagType, callback: request.RequestCallback): void;
+
+        /**
+         * Perform a GET request against the given URL.
+         * Used to get continued or paginated data from the API. Queries with long
+         * results return a reference to the next set.
+         * @param url
+         * @param callback
+         */
+        url(url: string, callback: request.RequestCallback): void;
+
+        /**
+         *
+         * @param callback
+         */
+        sp500_down(callback: request.RequestCallback): void;
+
+        sp500_up(callback: request.RequestCallback): void;
+    }
+}
+
+export = robinhood;