The JVM part hosts a Ktor HTTP server that serves a static WebApp frontend and exposes REST endpoints for inline query submission, WebApp data validation, custom emoji status setting, and prepared keyboard button management. The JS part is the WebApp itself — a single-page app with a button that communicates back to the bot and adapts to the user's Telegram theme and viewport.

Arguments

Position	Value	Description
1	`BOT_TOKEN`	Telegram bot token
2	`WEB_APP_URL`	Public HTTPS URL where the WebApp is hosted
3 (optional)	`PORT`	Port for the Ktor server (default: `8080`)

Optional flags:

Value	Description
`debug`	Enable verbose debug logging
`testServer`	Connect to the Telegram test server instead of production

Bot Commands

Command	Description
`/reply_markup`	Send a reply keyboard containing a WebApp button
`/inline`	Send an inline keyboard containing a WebApp button
`/attachment_menu`	Send an attachment-menu WebApp button
`/prepareKeyboard`	Retrieve and display the saved prepared inline keyboard button

Server Endpoints

Method	Path	Description
`POST`	`/inline`	Accept an inline query result submitted from the WebApp
`POST`	`/check`	Validate the `initData` signature sent by the WebApp
`POST`	`/setCustomEmoji`	Set a custom emoji status for the user based on WebApp data
`POST`	`/getPreparedKeyboardButtonId`	Return the ID of a previously saved prepared inline keyboard button

Capabilities

Serves the compiled JS WebApp as static files
HMAC-SHA256 validation of Telegram WebApp initData
Custom emoji status setting via setUserEmojiStatus
Prepared inline keyboard button saved with savePreparedInlineMessage
Supports all three WebApp button surfaces: reply keyboard, inline keyboard, attachment menu
Requires a domain with valid SSL (or a Telegram test account)
JVM server + Kotlin/JS frontend in a single Gradle multiplatform project

Launch

./gradlew :WebApp:run --args="BOT_TOKEN https://your.domain.com 8080"