Show HN: Petal, open-source CoScreen/ScreenHero finally free
Hi HN! I’m Jason Thomas, one of the founders of CoScreen. As some of you may know, Datadog sunset the CoScreen service on July 31st. Four of us from the original CoScreen team have spent the last couple months building a free and open source pair programming tool inspired by those that came before us: It’s called Petal ( https://github.com/kiruna-labs/petal ) Some history first, because when we started CoScreen we had hoped to break the sad and established pattern of this industry. Screenhero was an exceptional tool that a lot of us loved for pairing. Multiple cursors, low latency, you could click your partner’s editor, and just start typing. It felt like magic while we had it. Then Slack bought it in 2015, and shut down the standalone app in December 2017. When Till, Max, and I started CoScreen, we were aware of this history, and wanted to build an even more magical collaboration and screen sharing experience: the entire concept was “throw a window from your laptop up on someone else’s screen, and start collaborating with zero friction.” Datadog acquired us in 2022, and thus began the great adventure of adapting our real-time technology into Datadog products, while also continue developing CoScreen as a standalone tool from the Datadog ecosystem. Datadog invested in the product for years and we’re thankful for that. But CoScreen itself proved, like so many other screen sharing tool acquisitions, to be too tangential from the customer base and core mission. We instead built other communication features in Datadog, the integrations with other video platforms, and also its wildly successful MCP server. We weren't the only ones. Around was bought 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. It's nearly always the same story: a small team builds something hard that people love, a platform buys it for the team or the feature, and the standalone product doesn't survive the integration. So we decided firmly to do things differently this time. Petal is completely free and open source and we aren't monetizing it. If we lose interest or get hit by a bus, you can self-host it or fork it, and nobody can sunset it on you. Honestly it's a love letter to everyone in this community that supported us, believed in us, and to liberate collaborative screen sharing from this vicious cycle. We hope through this we can help foster a large and vibrant community around innovating in this product sector. What Petal does: shared windows show up as real windows on your desktop, movable and resizable, not tiles in a grid. Several people can share at once, everyone gets a labeled cursor, and you can click into any shared window to type and scroll. Rooms are persistent, so you click once to join "eng-sync" instead of passing links around. It runs on macOS and Windows (Linux is next, this time for real and you can help us!), plus a web app. Media goes over LiveKit. You can use our hosted instance with zero config, or point the app at your own LiveKit server with one docker-compose if you want the traffic to stay on your network or even use an entirely different video backend if you want to. The part that still feels strange to us: CoScreen took almost six years to build. The first version of Petal took under eight weeks, from scratch, with frontier models like Fable and Astra doing a lot of the work. Real-time video and window capture is some of the most unforgiving code we have ever written, so we didn't expect that. We will do a proper writeup on what worked and what didn't, and are happy to answer questions about it here. Till, Darren, Max and I will be in the thread.
Discussion Highlights (16 comments)
coscreen
Till here, another co-founder of CoScreen. Like Jason wrote, our launches on HN and the feedback by many of you in 2019 were really important all the way back to the earliest days of our small and fancy tool. We did a lot of things since we're proud of but a few plans remained unfulfilled, like support for Linux, until now. We'd love to work with you and see what you'll build, now that Petal is out in the open for anyone to use, jam on, and make it your own.
therealbithead
Thank you for your work, looking forward to the Linux version!
iovrthoughtthis
i loved screen hero but this is probably 10 years too late
jsherwani
Screenhero co-founder/CEO here — this is really great! It looks like we had similar feelings after leaving our acquiring companies with our products being sunset. Since leaving Slack, I've been building Pop with a new team. The first product we launched in 2020 is essentially Screenhero 2.0 (pop.com). Since then, we've been building an expanded product: a virtual office for remote teams, which is now almost ready for launch (there's a waitlist at https://new.pop.com ). We've even got Wayland support in! We have plans to open source a part of the Wayland piece, which Petal could potentially use too. I do love this space, and wish more tools were about live collaboration — it feels so much more human and fun than single-player mode. I hope Petal becomes a growing community that thrives for the long haul!
citizenfishy
This is just what we need in our small startup. It solves problems we have when working remotely and joint debugging along with walking our customers through tricky issues. Can't wait to give it a spin
yokto
Will give it a try! How is LiveKit working for you in terms of achieving low input2video latency? Did it lend itself to getting tuned for this application?
joshuat
Reminds me of Tuple ( https://tuple.app/ ), which was also billed as a Screenhero replacement
joeblau
Thanks for making this. We used co-screen so much that when you shut down, we had to build our own.
weakfish
I really wonder if it’s just me, but I have a deeply visceral reaction to AI copywriting that is largely irrational I’m willing to admit. > The media server — traffic stays yours The product looks cool! It’s just… reading that sentence makes me __immediately__ lose all interest.
lochnessduck
Thank you for this, I am a big fan of pair programming, and even jetbrains is getting rid of their code-with-me service! It’s so Frustrating to see a useful feature/tool get abandoned due to low usage. But those of us who use pair programming absolutely love it :) It’s a tool that helps further human connection, imo. And we could all use a little more of that atm.
smw
Just want to say thank you!! Screenhero was invaluable. Pop is pretty good, but open source is a game changer!
ripley12
Very very happy to see this! I was lucky to work with Till+Jason on CoScreen (I came in late); they're really exceptional people and CoScreen had a great collaboration UX that still hasn't been matched by Zoom and friends. Really keen to see what they'll be able to build this time around.
compounding-err
The self-hosting guide currently calls for running the token backend as well as LiveKit, then rebuilding the desktop app with the backend URL baked in. Is there a way to switch the released app to a self-hosted backend without rebuilding?
haddonist
Trying to view https://www.coscreen.co/ and seeing: "www.coscreen.co uses an unsupported protocol" SSL Labs report: Assessment failed: Failed to communicate with the secure server https://www.ssllabs.com/ssltest/analyze.html?d=www.coscreen....
dvt
This is super cool and thanks for open sourcing. I remember seeing CoScreen & Screen Hero here on HN years ago and thinking it was absolutely the cat's pajamas. Unfortunately, I think it was one of those cases of being blinded by the tech being super cool. Of the ~decade since I've seen these types of apps, I've never used one and, frankly, I never ever craved for "just sharing one window" or "playing in multiplayer" as @jsherwani put it. Which is kind of odd, because COVID came and went (peak remote/screen sharing days), and I had totally forgotten these kinds of products even existed. While this is (still) super neat technically, I just don't really see a concrete use case other than "lemme show you something super cool." Has anyone actually used it? Where would this kind of tool be better than just screen sharing over Google Meet or Discord or Slack or whatever?
morikyouko
As is common with lots of software like this, unfortunately, it looks like this product doesn't support Japanese/CJK text entry (with an IME popup and multiple input sources). This is a deal breaker for the Japanese/Chinese speaking market. It is not impossible to support as there are other apps that do properly support Japanese text entry. I was excited for an open source product for the reasons OP noted, but I'm very disapointed that it does not support my use case. Is there any plans for adding full international text entry support?