diff --git a/lib/timestamp.d.ts b/lib/timestamp.d.ts
new file mode 100644
index 0000000..072ed28
--- /dev/null
+++ b/lib/timestamp.d.ts
@@ -0,0 +1,57 @@
+interface Timestamp {
+  /**
+   * Set to `true` to round all returned timestamps to the second.
+   * @default false
+   */
+  round: boolean;
+
+  /**
+   * Gets the current time as Unix timestamp.
+   * Optionally applying a given offset specified as either a human-readable string or a number of
+   * seconds.
+   *
+   * @param offset The optional time offset to apply
+   * @returns The corresponding timestamp
+   */
+  now(offset?: string | number): number;
+
+  /**
+   * Applies the given offset to the given timestamp.
+   * The offset is specified as either a human-readable string or a number of
+   * seconds.
+   *
+   * @param time The original timestamp
+   * @param offset The time offset to apply
+   * @returns The result timestamp
+   */
+  add(time: number, offset: string | number): number;
+
+  /**
+   * Gets the offset timestamp for the given offset string.
+   * (Alias for .add() using a time of zero.)
+   *
+   * @param offset The time offset for the duration
+   * @returns The result time offset
+   */
+  duration(offset: string | number): number;
+
+  /**
+   * Gets the Unix timestamp for the given date object or string.
+   *
+   * @param date A date object or an ISO 8601 date string
+   * @returns The corresponding timestamp
+   */
+  fromDate(date: Date | string): number;
+
+  /**
+   * Gets the date for the given Unix timestamp.
+   *
+   * @param time A timestamp
+   * @returns The corresponding date
+   */
+  toDate(time: number): Date;
+}
+
+declare const timestamp: Timestamp;
+
+export = timestamp;
diff --git a/package.json b/package.json
index 8fac188..aaa6d42 100644
--- a/package.json
+++ b/package.json
@@ -17,6 +17,7 @@
   "license": "BSD-3-Clause",
   "author": "Simon Goumaz <simon@attentif.ch> (https://attentif.ch)",
   "main": "./lib/timestamp",
+  "types": "./lib/timestamp.d.ts",
   "files": [
     "lib"
   ],