After-hours mode

The u-x.cc arcade

Three tiny cabinets from the era of vector graphics and one-more-go.

3 cabinets · free play

6 projects · all free & open source

Small, sharp tools
built to last.

I'm Tony Mattsson, a random guy who grew up with the computer revolution. It started with the venerable ZX Spectrum 48K, which I used to type in listings from computer magazines. It took hours, and sometimes the machine just reset at random because of a semi-faulty power socket I never managed to fix. After that I learned techniques, tips and tricks on a plethora of now very obsolete computers such as the Atari 130XE, Spectravideo SVI 328, Atari 520 ST and Amiga 500, plus a whole succession of PCs — playing games, wasting time and picking up some coding techniques along the way. These days I work as a programmer, mostly with CMS, backend and frontend in .NET and LAMP (Linux).

The projects on this page are a mix of old things I built for myself and newer ideas, and I'm trying to let AI do the grunt work. It means I can build things that would have taken a small company's worth of programmers in the past and finish them on my own — while learning a lot of cool programming languages, platforms and techniques in the process.

Projects
6
Platforms
40+
Prebuilt binaries
34
Telemetry
0

The software

Six projects, no strings attached

Every project below is open source, builds from source on a normal toolchain, and ships pre-built binaries where it makes sense. Nothing here needs an account, a subscription, or a network connection.

BoltPack

v1.5

A file archiver that runs on an 8088 — and on your laptop

A lightweight archiver built for maximum portability. The archive core is strict ANSI C89 and compiles on virtually anything with a C compiler; platform-specific concerns (file I/O, encoding, GUI) live in isolated frontends. Same .bolt archive, from MS-DOS to modern Linux.

  • 40+ platforms, 8 CPU families — Linux, Windows, macOS, AmigaOS, Atari TOS, Classic Mac OS, MS-DOS, OS/2, RISC OS, Haiku, Plan 9, Solaris, z/OS, WebAssembly and more
  • Five compression methods — Stored, LZSS for 16-bit targets, fastlz, Fluff (LZ77 + FSE/tANS), and zstd 1.5.7 on modern builds
  • LAN transfer built inlisten, scan and --send stream archives straight to another machine on the network
  • Format v3 — per-block CRC-32, Unix permission bits, and normative archive size for early corruption detection
  • CLI, FLTK GUI, and Total Commander plugins for 32- and 64-bit Windows
  • ANSI C89
  • BSD-2-Clause
  • FLTK
  • OpenMP
  • WASM

ChecksumDrop

v1.1.0

Drag files in, get verified hashes out

A cross-platform hash generator and validation engine. Drop files or whole folders onto the window to generate a digest file next to your data — or drop an existing .sfv / .md5.txt and it flips into validation mode, recomputes everything, and reports what matches.

  • 12 algorithms — CRC32, MD5, SHA-1, SHA-256/384/512, SHA3-256/384/512, BLAKE3, xxHash64 and xxHash3
  • Recursive by default — drop a folder and every file below it is hashed, with paths stored relative to a common base
  • Validation mode with clear per-file status: OK, missing, or mismatch
  • Drag-and-drop that actually works on Linux — a custom X11 XdndProxy layer fixes drops under Cinnamon, Mutter and other reparenting compositors
  • Self-contained C11 build on raylib — no system hashing libraries required
  • C11
  • raylib
  • raygui
  • BLAKE3
  • X11 DnD

Download v1.1.0

Source on GitHub ↗  ·  macOS builds from source via ./build.sh osx.

DragFlac

v1.0.0

Lossless audio conversion, one drop at a time

A lightweight desktop app that converts audio to and from FLAC by drag-and-drop. Drop a file or an entire folder tree and it encodes in the background while the UI stays responsive — then shows you exactly how much space each file saved.

  • In: WAV, AIFF, FLAC  ·  Out: FLAC, or WAV when decoding back
  • Never blocks — encoding runs on a detached worker thread, so large batches don't freeze the window
  • Compression levels 0–8, with per-file size deltas reported after every run
  • Optional deletion of the source file after a verified encode, plus an error log for failures
  • Custom CLI parameters passed through to the system flac binary for advanced use
  • C11
  • MIT
  • raylib
  • libFLAC
  • libsndfile

Download v1.0.0

Source on GitHub ↗  ·  raylib and libFLAC are fetched automatically at configure time.

EncryptEd

v1.0

A text editor whose files are encrypted at rest

A small UTF-8 text editor that saves to .txx — a compressed and authenticated encrypted document format. Modern cryptography, a C17 core with no application logic in the UI layer, and a binary small enough to carry on a stick.

  • XChaCha20-Poly1305 + Argon2id via Monocypher, with a fresh salt and nonce generated on every save
  • Tamper-evident — the 96-byte header is authenticated as AEAD associated data, so any modification fails the auth check
  • Three frontends — an FLTK desktop GUI, a full terminal editor (etui) built on FTXUI, and a CLI for scripted pack/unpack
  • Real UTF-8 handling — detects and transcodes UTF-16, Windows-1252 and ISO-8859-1, and analyses line endings
  • Payload is DEFLATE-compressed before encryption; the Windows installer associates .txx files
  • C17
  • C++17
  • GPL-3.0
  • Monocypher
  • FLTK
  • FTXUI

Download v1.0

Source on GitHub ↗  ·  the .txx format is documented in full in docs/txx-format.md.

TimeReport

v1.1.0

Log your hours, export a clean Markdown report

A lightweight desktop time tracker for logging work entries and exporting them as Markdown tables. Built on Avalonia UI and .NET, it runs the same on Windows, Linux and macOS, and keeps everything in a local SQLite file — no account, no server, no network connection.

  • Fast entry — description, project, start and end time, with day-by-day navigation
  • Markdown export for any date range, ready to paste into an invoice or a report
  • Bilingual UI — English and Swedish, switchable at runtime
  • Yours alone — all data lives in TimeReport.db under your local config directory
  • Per-user Windows installer, no admin rights required
  • C#
  • .NET 10
  • Avalonia
  • SQLite
  • MIT

LocalHero

v0.1.0

A coding assistant that never leaves your machine

A keyboard-driven terminal coding assistant backed by local inference. Point it at a git repo, pick what the model sees, and review every proposed edit file by file before it touches disk. Ollama by default, with llama.cpp or any OpenAI-compatible server as alternatives. No cloud required.

  • Five screens, all keyboard — Files (F1), Ask AI (F2), Editor (F3), Review (F4), Settings (F9)
  • Gated edits — proposed changes land on a per-file diff screen; accept or reject individually, with a git snapshot taken before the first write as an undo net
  • Local RAG — build a SQLite embeddings index for repos too large to hand-pick, so relevant chunks are retrieved automatically
  • Opt-in extras — sandboxed calculator, approval-gated shell commands, private web search via Brave or self-hosted SearXNG, and a verify-then-auto-fix test loop
  • Sessions autosave per project and resume; Ctrl+T shows exactly what was sent on the last turn
  • Python 3.11+
  • MIT
  • Textual
  • Ollama
  • llama.cpp

Install — published on PyPI

$ pipx install localhero
$ uvx localhero

Needs a running Ollama server — ollama pull gemma4 gets you started. A terminal app, so there's no binary to download.

About

Why any of this exists

I'm a professional programmer, and this site is where the things I build outside of work end up. Most of them started as a small annoyance — a file that wouldn't move between two machines, a checksum I couldn't verify on Linux, hours I kept forgetting to write down — and turned into something worth finishing properly.

There's a common thread. Everything runs locally. Nothing needs an account or a subscription, nothing collects telemetry, and the data stays in a file you own on a disk you control. Where a project can ship as one self-contained executable, it does.

BoltPack is the odd one out, and my favourite: I wanted to go back to my ANSI C days, so the archive core is strict C89 and targets everything from an 8088 running DOS to a RISC-V box. Some of these projects lean on AI for the heavy lifting during development — BoltPack in particular would have been well out of scope otherwise.

It's all free, all on GitHub, and all open to issues and pull requests.

What I build with

  • Systems ANSI C89, C11, C17, C++17 — raylib, FLTK, FTXUI
  • Desktop C# on .NET 10 with Avalonia UI
  • Terminal Python 3.11+ with Textual
  • Crypto Monocypher — XChaCha20-Poly1305, Argon2id
  • Local AI Ollama, llama.cpp, OpenAI-compatible servers
  • Build CMake, Make, mingw-w64 cross-builds, NSIS, GitHub Actions
  • Licenses MIT, BSD-2-Clause, GPL-3.0

Questions, bugs, or ideas?

Bug reports and feature requests are best filed as GitHub issues on the relevant project — but if you'd rather just send a note, that works too.