Posterium is a service for scheduled posting, maintaining and promoting channels in Telegram.
Posterium includes:
Telegram Bot @Posteriumbot — basic chat version of the bot.
Mini App Posterium — internal telegram application, optimized for mobile devices.
Website posterium.pro— web version, great for working with a PC.
To get started, you need to create a personal bot via chat with @Posteriumbot or Mini App Posterium and add your channels.

Connecting a bot in chat
Click ⭐Begin
Select your time zone: click Detect automatically, a separate Mini App page will open and the bot will detect the time zone set on your device, click I confirm, Mini App will close.

You can set a different time zone in the Mini App by clicking Choose another, or in chat by clicking Select manually.
Creating a bot
Click ✨Create a bot
In the window that opens, enter (make up your mind) bot name (any) and username (bot username). Username must be unique and contain the word at the end bot (substituted automatically). Then click Create. In the menu that appears, click 🚀Go to bot

Alternative: click 🤵Create a bot via BotFather, and either create a bot and copy the token, or copy the token of an existing (but not used anywhere) bot and send it to the chat.
Channel connection
Click Start the bot
Click ➕Connect channel

In the window that opens, select the channel you want to connect. Leave the bot the rights to Publication management 3/3 and press Add a bot as an administrator. In the pop-up window, confirm the action by clicking Assign.
After adding a channel, return to the chat with the bot. Click ➕Add another channel, if necessary, or 🏠Go to main menu, if you want to end the process.

After this, you can start creating posts:
Connecting a bot in Mini App
Open the Mini App by clicking on the 🌟 buttonStart in Mini App or button Posterium in the text input field.

If necessary, change the language in the menu that opens and click Start setting up⮕
Confirm your time zone (it should be determined automatically) or select the one you need. You can also change the date and time display format.

Creating a bot
Click Create a bot in Telegram⮕
In the window that opens, enter (make up your mind) bot name (any) and username (bot username). Username must be unique and contain the word at the end bot (substituted automatically). Then click Create.

The Mini App will collapse and you will be in a chat with your bot. You can continue in the chat or in the Mini App.
Adding a channel
Expand the Mini App (by clicking on Posterium below), you will see a notification in the menu that opens Bot is connected, press Next ⮕

Click Connect channel, Mini App will collapse and your channel list will open. Select the desired channel.
Leave the bot the rights to Publication management 3/3 and press Add a bot as an administrator. In the pop-up window, confirm the action by clicking Assign.

Expand Mini App. If you want to connect other channels, repeat the operation: press again Connect channel, select the desired channel and give the bot rights to manage publications. Then click Next ⮕
Click Get started ⮕.

After this, you can start creating posts: