diff --git a/lib/index.d.ts b/lib/index.d.ts
new file mode 100644
index 0000000..2466562
--- /dev/null
+++ b/lib/index.d.ts
@@ -0,0 +1,74 @@
+// Code shows a string is valid,
+// but docs require string array or object.
+type TLDList = string | string[] | { [topLevelDomain: string]: any };
+
+type BaseOptions = {
+  tldWhitelist?: TLDList;
+  tldBlacklist?: TLDList;
+  minDomainAtoms?: number;
+  allowUnicode?: boolean;
+};
+
+type OptionsWithBool = BaseOptions & {
+  errorLevel?: false;
+};
+
+type OptionsWithNumThreshold = BaseOptions & {
+  errorLevel?: true | number;
+};
+
+interface Validator {
+  /**
+   * Check that an email address conforms to RFCs 5321, 5322, 6530 and others.
+   *
+   * The callback function will always be called
+   * with the result of the operation.
+   *
+   * ```
+   * import * as IsEmail from "isemail";
+   *
+   * const log = result => console.log(`Result: ${result}`);
+   * IsEmail.validate("test@e.com");
+   * // => true
+   * ```
+   */
+  validate(email: string): boolean;
+
+  /**
+   * Check that an email address conforms to RFCs 5321, 5322, 6530 and others.
+   *
+   * The callback function will always be called
+   * with the result of the operation.
+   *
+   * ```
+   * import * as IsEmail from "isemail";
+   *
+   * IsEmail.validate("test@iana.org", { errorLevel: false });
+   * // => true
+   * ```
+   */
+  validate(email: string, options: OptionsWithBool): boolean;
+
+  /**
+   * Check that an email address conforms to RFCs 5321, 5322, 6530 and others.
+   *
+   * The callback function will always be called
+   * with the result of the operation.
+   *
+   * ```
+   * import * as IsEmail from "isemail";
+   *
+   * IsEmail.validate("test@iana.org", { errorLevel: true });
+   * // => 0
+   * IsEmail.validate("test @e.com", { errorLevel: 50 });
+   * // => 0
+   * IsEmail.validate('test @e.com', { errorLevel: true })
+   * // => 49
+   * ```
+   */
+  validate(email: string, options: OptionsWithNumThreshold): number;
+}
+
+declare const IsEmail: Validator;
+
+export = IsEmail;
diff --git a/package.json b/package.json
index 1d876c6..5109a30 100644
--- a/package.json
+++ b/package.json
@@ -4,6 +4,7 @@
   "version": "3.1.0",
   "repository": "git://github.com/hapijs/isemail",
   "main": "lib/index.js",
+  "types": "lib/index.d.ts",
   "keywords": [
     "isemail",
     "validation",