diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..ea7d616
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,38 @@
+export type TweetParams = {
+  text?: string,
+  url?: string,
+  via?: string,
+  related?: string | string[],
+  in_reply_to?: string,
+  hashtags?: string | string[],
+}
+
+export type EngagementParams = {
+  tweet_id?: string
+  related?: string | string[],
+}
+
+export type UserParams = {
+  screen_name?: string
+  userid?: string
+}
+
+export namespace tweet {
+  function url(params: TweetParams): string
+}
+
+export namespace favorite {
+  function url(params: EngagementParams): string
+}
+
+export namespace retweet {
+  function url(params: EngagementParams): string
+}
+
+export namespace user {
+  function url(params: UserParams): string
+}
+
+export namespace follow {
+  function url(params: UserParams): string
+}