LearnCLI — an offline study tool I built on my phone for a friend prepping for JEE

Apurv — Sun, 04 Oct 2026 19:15:14 +0000

This is a submission for the Hacktoberfest Weekend Challenge: Build for a Friend

What I Built

A friend of mine is prepping for JEE and keeps hitting the same problem — she's studying somewhere with spotty internet, and every "AI study helper" out there needs a connection and usually a subscription. So I built LearnCLI: a tiny terminal tool that explains a topic and throws a practice question back at you, running fully offline.

You type a topic, it thinks for a few seconds, and it gives you a plain-text explanation plus one question to test yourself with. No account, no internet, no API bill.

The twist is I didn't have a laptop while building this. I did the entire thing on my phone, in Termux.

Demo

(this is a real run asking it to explain Newton's third law)

Code

Repo: https://github.com/krvnium/LearnCLI

How I Built It

Everything runs through llama.cpp, compiled straight from source inside Termux on my Poco M4 Pro. No GPU, no cloud box, just phone CPU.

For the model, I went with Gemma 3 1B, quantized down to Q4_K_M (~800MB), small enough that it actually runs at a usable speed on a phone.

The script itself is plain Python, calling the compiled llama-cli binary and cleaning up its output — stripping markdown symbols the model likes to throw in, cutting off a marker token I use internally to separate the prompt from the actual answer, and wrapping everything in a little terminal UI so it feels less like a raw model dump and more like an actual tool.

Build process, roughly:

pkg install the usual suspects (clang, cmake, git, python) in Termux
clone and compile llama.cpp natively on-device
pull the Gemma GGUF from Hugging Face
write the Python wrapper around it

Why Does Open Innovation Matter?

This only works because the model weights and the inference engine are both open. Gemma being open-weight means I can download it once and run it forever, no API key, no per-request cost, no "service unavailable" when my friend's hostel wifi dies at 11pm before an exam. llama.cpp being open-source is the other half — it's what let me actually get a transformer model running on a phone's CPU without needing anyone's permission or infrastructure.