Indie developer SaaS / macOS / BI @Berliner187

Rostislav
Kozak.

I run Letychka, a SaaS that turns lecture files into online tests. I also write a dictation app for macOS in Swift and build BI and ETL for companies.

01Main productsince 2024

2024 — now Running

LetychkaЛетучка

A teacher uploads a PDF or DOCX, or pastes text, and gets a ready online test.

Students open it by link or QR code, with no registration. Answers are checked automatically, and the teacher sees which topics students got wrong most often. Built for teachers, tutors, university departments and company training teams.

4500+users · RU interface
Input
PDF, DOC/DOCX, TXT up to 25 MB, or pasted text up to 100,000 characters
Tests
Three difficulty levels, single or multiple correct answers, shuffled options, editing of any question
Students
Link or QR code, no account needed
Results
Automatic scoring, per-question statistics, Excel export, printable A4 sheets with an answer key
Open letychka.ru
For teachers Product Radar

Python / Django / PostgreSQL / Redis / Celery / LLM

02Projects by year2021–2026

  1. In development

    GolosokГолосок

    Offline dictation for macOS. Press ⌥ Space, speak, and the text appears at the cursor in any app. Recognition runs locally on GigaAM v3 or Whisper, using the GPU and Neural Engine of Apple Silicon, so audio stays on the Mac.

    • v1.13.9
    • MIT
    • macOS 13+
    • Apple Silicon
    • Free

    Swift / Metal / Core ML / GigaAM-v3 / Whisper

  2. Running · main product

    Letychka

    Online tests from lecture files. See above

  3. Running

    Taxi Watcher

    A Telegram bot that watches ride-hailing prices on a chosen route and writes when the fare drops.

    Python / asyncio / Telegram Bot API

2021–23Archive: 2 early repos

Personal projects that were never released and are no longer maintained. The code is on GitHub as is.

  1. Finanzfluss

    Command-line budget tracker: income, expenses and account balances. Python, CLI.

    Source

  2. Elba

    Offline password and notes manager with local encryption. Python, GPL-3.0.

    Source

03Stack

Products
Python, Django, FastAPI, PostgreSQL, Redis, Celery, Docker. Swift, Metal, Core ML on macOS
Data & BI
Apache Airflow, ETL, Pandas, SQL, Visiology, semantic layer design

04Contact