Jang-Ho Hwang

There has never been a better time to build things.

Frontend, infrastructure, product: if something isn't getting done, I'd rather do it myself. I work fully remote from Berlin, and this blog goes back to 2004.

Even on days off, I'm usually building something.

6,091 contributions on GitHub in the past year github.com/rath

Things I've open-sourced

  • Portway 2026 · Rust

    A local proxy for coding agents

    Each request crosses the network as the difference from the previous turn, so a 1 MiB conversation uploads about 1 KiB. It also routes by model and records tokens and cost, which a terminal dashboard and a web console show live.

  • vtamp 2026 · Rust

    A music player for the terminal

    Playback runs in a background server, so closing the interface or detaching from tmux never stops the song. Local files and live radio in one queue, album art drawn in the terminal, macOS media keys and Now Playing, and a JSON CLI for scripts and agents.

  • iotap 2026 · Rust · eBPF

    Every file and network read and write a process makes, as it happens

    A command-line tool for macOS and Linux that shows the path or address, the bytes, and the latency of each call. It works from the kernel's own record of system calls, so the program runs untouched, and it keeps only metadata, never the data itself.

  • Vimdow 2013, 2026 · Swift

    A macOS window manager driven by Vim keys

    Move, resize, and snap windows with hjkl, counts, and undo. First written in Objective-C in 2013, rewritten in Swift in 2026.

  • Orrery 2026 · TypeScript · React

    Saju, Zi Wei Dou Shu, and Western natal charts in the browser

    Calculated entirely in the browser with no server. The engine is also on npm.

  • Sonica 2026 · Rust · wgpu

    A visualizer video from an audio file

    FFT analysis, WGSL shaders on the GPU, and an MP4 at any resolution or aspect ratio.

  • Zitat 2026 · Python

    Translated subtitles for a clip of a YouTube video

    Clips part of a video, transcribes it with Whisper, translates the subtitles with Claude, and burns them in, with a review step before the final render.

What I'm building at work these days

  • BizRouter 2025 · Rust · React · Django

    An LLM gateway for Korean companies

    One API key for a dozen AI providers, billed in won. I built everything from the Rust proxy to the admin console. These days new people are working on it, so my commits have slowed down.

  • Wrks AI Image 2026

    An image generator that doesn't require prompt skills

    Pick a purpose, type in plain Korean, and you get an image.

  • Wrks AI Video 2026

    A short video from one line of Korean

    Describe a scene and get a short video, sound included.

  • Wrks AI Notes 2026

    Meeting notes from a recording

    Transcribes meeting recordings by speaker and pulls out decisions and action items.

The last three I build alone, from planning and design through development, operations, and infrastructure. In between, I put newly released models on H100s to see what they can do.

Things I build for myself

  • Anvil 2026 · Python · MLX · React

    Dictation, TTS, and chat on my Mac with no cloud

    One shortcut from the menu bar for voice input anywhere.

  • Morax 2026 · SwiftUI · Bun

    An iOS app that turns spoken thoughts into tasks, events, and notes

    Audio is transcribed on the device and never leaves it.

  • Burrow 2026 · SwiftUI · Rust

    A messenger for a handful of close friends, on iOS and macOS

    Passkey sign-in, photos, videos, and calls.

  • Butter 2023 · Rust · Flutter

    A personal app for habits, notes, and photos

    The server accepts client certificates only.

Screenshots and longer notes on the open-source tools, my older iOS apps, and Mouton Journal are on the works page.

Recent posts (in Korean)

  1. 술 취한 Claude Code 길들이기
  2. 로컬 AI 모델의 황금기
  3. LLM 시대에도 GUI는 사라지지 않는다
  4. Python 3.14 개발자 친화적 업데이트들
  5. 바이브 코딩을 무시하는 시니어들에게
  6. 체지방 9kg 감량과 함께 찾아온 변화들

See all 908 posts