CoScreen founders released Petal, an open-source pair-programming tool

Pair-programming tools have been acquired and shut down three times in a decade. Jason Thomas, who co-founded CoScreen in 2019 and sold it to Datadog in 2022, decided to try again with four engineers from his former team after Datadog sunset CoScreen on 31 July. The result is Petal, released as open source on Hacker News, which reached 84 points in its first three hours.

The code is at github.com/kiruna-labs/petal under Apache 2.0, with 69 stars at the time of writing. The hosted service and the download pages are at petal.live.

What the app does

A shared window from one participant's desktop shows up as a real native window on every other participant's desktop. It is movable and resizable like any other window on the system, keeps its own frame when nothing changes, and holds its last frame on screen when the compositor would otherwise show black. Several people can share at the same time. Everyone gets a labelled cursor on every shared window. A click anywhere on a shared window types and scrolls as if the window were local.

Rooms are persistent. A team sets up a room like eng-sync, joins with one click, and never passes a link around. The desktop app runs on macOS and Windows, with Linux listed as the next platform. A web app covers the rest.

How the backend works

Media goes over LiveKit. There are three ways to run it. The hosted Petal Cloud is free, uses LiveKit's video infrastructure, and needs no setup. A self-hosted media server runs from one docker-compose and keeps all the traffic on the team's own network, which the project describes as the compliance and data-control path. The third option is a full fork, where a team changes the app and brings its own stack.

The history Jason Thomas cites

Thomas's launch post lists the pattern each shutdown followed. Screenhero was acquired by Slack in 2015 and the standalone app went away in December 2017. CoScreen was acquired by Datadog in 2022 and sunset on 31 July. Around was acquired by Miro and shut down in March 2025. Multi, formerly Remotion, was acqui-hired by OpenAI in 2024 and shut down about a month later. The failure mode he names: a small team builds something hard that a community loves, a platform buys it for the team or the feature, and the standalone product does not survive the integration.

Thomas also writes that CoScreen took almost six years to build and that the first version of Petal took under eight weeks from scratch, with frontier models from Anthropic and OpenAI doing a lot of the work on real-time video and window-capture code. The team plans to publish what worked and what did not.

Source

Show HN discussion by Jason Thomas, the project repository at github.com/kiruna-labs/petal, and the hosted service at petal.live.