A big chunk of my course material lived inside Telegram channels: lectures, notes, and PDFs. That is fine until you actually try to study offline. So I built a bulk downloader with Telethon that archives an entire channel in order, with resume support, so I could learn from VLC and a PDF reader instead of an endless scroll.

#The problem: my college ran on Telegram

In India, a huge amount of student material such as coaching lectures, notes, and previous papers gets shared through Telegram channels. Scrolling through months of history, dealing with slow in-app playback, and the constant worry of a channel getting taken down made it painful to rely on. I wanted a clean offline copy I could open in VLC or any reader.

#What it does

It downloads images, audio, video, and documents (PDF, Word, Excel, PowerPoint, ZIP/RAR/7z, text/CSV, and more) from a channel in chronological order, naming each file so the sequence stays intact.

• ▹Works with public channels, t.me links, and private invite links
• ▹Chronological numbering like 0000000001 - lesson title.mp4
• ▹Caption-based, ASCII-safe filenames that respect Windows path limits
• ▹Resume support: finished files are skipped via a manifest.json
• ▹Multipart segmented downloads for big videos, plus retries, FloodWait handling, and integrity checks
• ▹A live Rich dashboard so you can watch progress in the terminal

#Quick start

You need Python 3.11+ and API credentials from my.telegram.org/apps. Set up a virtual environment and install the requirements:

python -m venv .venv
.\.venv\Scripts\Activate.ps1
pip install -r requirements.txt
copy .env.example .env

Set TG_API_ID and TG_API_HASH in .env, then point it at a channel:

python tg_downloader.py https://t.me/your_channel_username

The first run asks for your phone number, an OTP, and (if enabled) your two-step password. After that a session file keeps you logged in. Files land under downloads/<Channel Name>/, and re-running the same channel continues right where you left off.

#Squeezing out 10–15 MB/s

Telegram rate-limits aggressive downloaders, so more workers is not always faster. A stable starting config looks like this:

TG_MAX_GLOBAL_DOWNLOADS=2
TG_ENABLE_MULTIPART=true
TG_PART_SIZE_MB=8
TG_MAX_PARALLEL_PARTS=4
TG_REQUEST_SIZE_BYTES=2097152

Installing cryptg speeds up encryption a lot. On Windows, the biggest real-world wins came from saving to an SSD, adding Defender exclusions for the project and downloads folders, and using Ethernet over Wi-Fi.

#Lessons learned

• ▹Resume-by-manifest is the feature that made it genuinely usable; big channels take hours
• ▹ASCII-safe, length-capped names fixed VLC's “unable to open MRL” errors caused by long paths
• ▹Backing off on FloodWait beats hammering the API and getting throttled harder

If you also study from Telegram, the code is on GitHub. Clone it, drop in your API keys, and point it at your channel.