diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..cd1dc10
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,134 @@
+declare module "sializer";
+
+declare type BinaryData = Buffer;
+
+declare type InternallySupportTypes =
+  | null
+  | undefined
+  | string
+  | number
+  | Record<PropertyKey, unknown>
+  | Set<unknown>
+  | Map<unknown, unknown>
+  | Buffer
+  | InternallySupportTypes[];
+
+type PrototypeConstructor<T> = Function & { prototype: T }
+type ConstructorFunction<T> = abstract new(...args: any[]) => T
+
+/**
+ * @example
+ * ```
+ * import {ConstructorFactory, Sia} from "."
+ * 
+ * const arrayBufferFactory: ConstructorFactory<ArrayBuffer, [Buffer]> = {
+ *     code: 0, // Unique POsitive Integer
+ *     constructor: ArrayBuffer,
+ *     args: (item) => [Buffer.from(item)],
+ *     build: (buffer) => Uint8Array.from(buffer).buffer,
+ * };
+ * const s = new Sia({constructors : [arrayBufferFactory]});
+ * ```
+ */
+export declare interface ConstructorFactory<T, R extends InternallySupportTypes[] = InternallySupportTypes[]> {
+  /**
+   * The custom class you want to support
+   */
+  constructor: PrototypeConstructor<T> | ConstructorFunction<T>;
+  /**
+   * A unique positive code point for this class, the smaller the better
+   */
+  code: number;
+  /**
+   *  A function to serialize the instances of the class
+   */
+  args: (item: T) => R;
+  /**
+   *  A function for restoring instances of the class
+   */
+  build: (...data: R) => T;
+}
+
+declare type SiaOption = {
+  /**
+   * The maximum size of buffer to use
+   * @remarks
+   * Use a big size if you're expecting to serialize huge objects
+   */
+  size?: number | undefined;
+  /**
+  * An array of extra types and classes, it includes instructions for deserializing the custom types and classes.
+  */
+  constructors?: Array<ConstructorFactory<any,any>>;
+};
+
+declare type DeSiaOption = {
+  
+  /**
+   * The minimum size of string map array to use.
+   * @remarks
+   * Use a big size if you're expecting to serialize huge objects
+   */
+  mapSize?: number | undefined;
+  
+  /**
+   * An array of extra types and classes, it includes instructions for deserializing the custom types and classes.
+   */
+  constructors?: Array<ConstructorFactory<any,any>>;
+};
+
+/**
+ * Makes an instance of Sia serializer using the given options.
+ * @example
+ * ```
+ * const sia = new Sia({
+ * size = 33554432, // Buffer size to use
+ * constructors = builtinConstructors // An array of extra classes and types
+ * });
+ * const buf = sia.serialize(data);
+ * ```
+ */
+export declare class Sia {
+  constructor(option?: SiaOption);
+
+  public serialize<T>(data: T): BinaryData;
+}
+
+/**
+ * Makes an instance of Sia deserializer using the given options.
+ * @example
+ * ```
+ * const desia = new DeSia({
+ * mapSize = 256 * 1000, // String map size
+ * constructors = builtinConstructors, // An array of extra classes and types
+ * const data = desia.deserialize(buf);
+ * ```
+ */
+export declare class DeSia {
+  constructor(option?: DeSiaOption);
+
+  public deserialize<T>(buffer: BinaryData): T;
+}
+
+/**
+ * Serializes the given data using the default parameters.
+ * @example
+ * ```
+ * const buf = sia(data);
+ * ```
+ */
+export declare const sia: <T>(data: T) => BinaryData;
+
+/**
+ * Deserializes the given BinaryData using the default parameters.
+ * @example
+ * ```
+ * const data = desia(buf);
+ * ```
+ */
+export declare const desia: <T>(data: BinaryData) => T;
+
+/**
+ * Array of default constructors used both by Sia and DeSia.
+ */
+export declare const constructors: ReadonlyArray<ConstructorFactory<any, any>>;
\ No newline at end of file