MTProto vs. Bot API
Unlike many existing libraries and frameworks for Telegram in TypeScript/JavaScript, mtcute uses MTProto, and not Bot API.
This allows mtcute to be much more flexible and support many features that Bot API does not.
What is Bot API?
Telegram Bot API, or simply Bot API, is an HTTP(s) interface provided and hosted by Telegram that allows developers to build bots.
Under the hood, Bot API uses TDLib (which in turn uses MTProto API), and simply provides HTTP methods that closely correlate with TDLib methods.
What is MTProto API?
MTProto is the custom protocol invented by Nikolai Durov and his team, consisting of six ACM champions, half of them Ph.Ds in math. It took them about two years to roll out the current version of MTProto (source). It is used to communicate between clients and Telegram servers.
On the surface, MTProto API is basically an RPC, where MTProto and TL are used behind the scenes to serialize, encrypt and process the requests. Sounds like VK API with extra steps, right?
Why MTProto?
MTProto clients (like mtcute) connect directly to Telegram, removing the need to use additional transport layers like HTTP, polling or webhooks. This means less overhead, since the data is sent directly to you, and not passed through the Bot API server and then sent to you via HTTP:
Apart from smaller overhead, using MTProto has many other advantages, including:
| Bot API | MTProto | |
|---|---|---|
| Userbots | Only bots | Both bots and users. |
| Files | 20 MB download, 50 MB upload. | No limits (except global limit of 2000 MB) |
| Objects | Often brief and non-exhaustive | Exposes anything you can think of |
| Updates | Only a limited subset | Updates about virtually anything that had happened |
| Errors | Often non-informative (e.g. slow mode is the same as flood wait) and not machine-readable | Informative and simple to use |
| Version | Receives updates slower | Updates with the TL layer |
| Compatibility | Updates randomly, you have to prepare for the upcoming breaking changes. Attempts to stay backwards-compatible, leading to weird hacks | You can stay on older version for as long as you need |
Note: the above table assumes official Bot API instance, hosted at
api.telegram.org. Self-hosted and/or custom Bot API instances bypass some of these limitations.
Why not MTProto?
Everything has its drawbacks though.
Using mtcute instead of Bot API (or TDLib) for high-load bots might currently not be the best idea, since TDLib caches basically everything, while mtcute doesn't. This is our primary focus for the upcoming releases, though.
If your bot is high-load, and you receive errors like 500 and 429, this definitely means a problem on mtcute side. Please let us know, so we can investigate further.
Another drawback is that due to mtcute being an enthusiast project, it does not offer the same level of robustness and support as Bot API, and is missing some features that Bot API has.