Opening

After Datadog shut down CoScreen, the original four-person team rebuilt it as the open-source Petal, which shot to 220 points on Hacker News right out of the gate. In this episode we'll also talk about BetterWispr, a dictation tool that also hit 220 points and 127 comments, plus anatomy, a tool that hit 14k stars in 30 days by having AI draw machines to explain technical concepts. How to use them, coming right up.

This Week's Open Source Picks

1. Petal: The Free Open-Source CoScreen, Turning Screen Sharing into Real Windows on Your Desktop

• What it is: After Datadog shut down CoScreen on July 31, 2026, the original four-person team rebuilt it as a free, open-source version (Apache-2.0) to fix the pain point of remote code reviews and pair programming, where "screen sharing turns into a tiled wall and you can't pass your mouse over." The window you share shows up as a genuine native window on the other person's computer, not a tiled frame embedded inside meeting software. That said, the team is upfront that the project is still pre-1.0: the Windows version's own description says "basic sharing works, but still incomplete and buggy," and the Linux desktop app isn't supported yet.
• This week's buzz: 220 points on Hacker News (41 comments).
• Highlights:
  • The shared window appears as a movable, resizable native window on the other person's desktop, and multiple people can each share their own windows simultaneously
  • Each shared window shows a name-labeled cursor; once you hand over control to a colleague, their mouse clicks and keystrokes get injected directly into that window
  • Named persistent rooms plus petal://join/<code> invite links mean you don't have to reopen a scheduling link every time, and you can also log in with a code via meet.petal.live in your browser
• Quick start: Download the macOS or Windows desktop app from petal.live and open a room instantly with zero setup using the official hosted service; if you don't want to install anything, just go to meet.petal.live and join with a code in your browser. For full self-hosting, follow docs/SELF_HOSTING.md to run a docker-compose setup, with media routed through a LiveKit SFU so traffic stays on your own network.
• How it compares: Compared to Zoom or Google Meet's screen sharing, Petal shares a single window that becomes a native window on your desktop and supports two-way remote control, making it more like the now-defunct CoScreen/ScreenHero. Compared to VS Code Live Share, it isn't tied to any editor, terminal, browser, or Figma, you can share all of them.
• Who it's for: Teams doing frequent remote pair programming or cross-timezone code reviews who want a stable tool that no one can shut down again.
• Link: petal.live

2. BetterWispr: A Local-Running, Account-Free Dictation Tool for Mac

• What it is: Engineers who type dozens of prompts to AI agents every day know how tiring manual typing gets. BetterWispr is a completely free and open-source (Apache-2.0) dictation tool for Mac: hold ⌥ Space, speak, release, and the text gets sent into whatever app you're using. It runs entirely locally, no account, no API key needed, directly addressing the pain point of subscription-based dictation services like Wispr Flow.
• This week's buzz: 220 points on Hacker News (127 comments).
• Highlights:
  • Built-in local transcription models. The README states plainly, "your voice never leaves your computer unless you add an API connection yourself." You can choose Apple's built-in engine, NVIDIA Parakeet v3/v2, or Whisper large-v3 turbo, and once downloaded, they work offline
  • Automatically strips filler words, repetitions, and self-corrections, with adjustable intensity, and can switch between casual and formal tone depending on which app you're in
  • A meeting-recording mode labels your own voice as "Me" and audio from other apps as "Them," auto-generates a summary when the meeting ends, and includes a vocabulary-learning feature that remembers names and corrections you've made
• Quick start: Grab the DMG for your architecture (arm64 or x86_64) from betterwispr.com or GitHub Releases and drag it into Applications, no Homebrew install option. Requires macOS 14 or later, Apple Silicon recommended.
• How it compares: Its direct counterpart is subscription dictation services like Wispr Flow. BetterWispr is completely free, requires no registration, and has no cloud fallback. Compared to macOS's built-in dictation, it adds filler-word cleanup, per-app tone switching, dual-channel meeting recording, and the option to swap in Whisper or Parakeet models.
• Who it's for: Engineers who spend all day talking to AI agents and would rather not type out every instruction.
• Link: betterwispr.com

3. anatomy: Get AI to Invent a Machine to Explain Technical Concepts

• What it is: When writing technical docs, making slides, or writing blog posts, explaining an abstract concept (like a rate limiter) often leaves you stuck drawing boxes and arrows. anatomy is an agent skill you install into Claude Code or Codex. Run one command and the AI invents an actual physical machine, using how it operates to turn an abstract concept into an animated, interactive isometric diagram.
• This week's buzz: A new project on GitHub within the past 30 days, already at 14.0k stars (13,982 stars), MIT licensed.
• Highlights:
  • Instead of drawing abstract boxes, it invents a physical machine to explain the concept, for example, running /anatomy explain how a token bucket rate limiter works, interactive
  • Three output tiers: pure SVG (shadows, motion, live readouts), SVG plus WebGL (fire, water flow, caustics, lighting), and a 3D beta (real rotating 3D parts with per-frame relighting), gracefully falling back to SVG if WebGL isn't available
  • Output can be a standalone HTML page, a single SVG file, or a React/Next.js component you drop straight into an existing project. The repo includes eight complete examples, including a percentage gauge, a large arcade machine, and a Raptor 2 engine test stand
• Quick start: Run npx skills add wheresryan22/anatomy -g -a claude-code (Codex uses -a codex; opencode, antigravity, and minimax-code are also supported). After installing, type /anatomy <你要解釋的東西> in Claude Code ($anatomy for Codex).
• How it compares: Compared to diagramming tools like Mermaid, D2, or Excalidraw, anatomy isn't about drawing charts, it generates animated, interactive isometric mechanical illustrations with live readouts. The README itself draws a clear line here too, noting it isn't meant for data visualization and doesn't draw people or maps, and it's intentionally slow because it requires multiple rounds of validation.
• Who it's for: Engineers or speakers who frequently need to explain abstract technical concepts to others and want something visually memorable.
• Link: github.com/wheresryan22/anatomy

Closing

All three of these are examples of pain points that used to cost money or time, now patched up open-source by a single person or a small team. If I could only install one, I'd go with BetterWispr first, because the moment you install it, you feel the difference. But Petal's story, a tool no one can shut down again, and anatomy turning abstract concepts into moving machines, are both worth keeping in your back pocket too. That's this week's open source roundup. We'll dig up a few more gems same time next week. See you then.