Mobile AI Lab. We train specialized models & build tools for agentic mobile development: @apex__ai + @agent_device. Hosting @AgentConf. React Native experts.
Wroclaw, Poland
Joined August 2016
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Callstack Engineers retweeted
Exact with @e2e agentic end-to-end testing running day one
Callstack Engineers retweeted
Powered by @agent_device. Our tool is framework agnostic and instead we focus on supporting as many native platforms as we can, preparing for the upcoming advent of new solutions (bespoke Shopify, Discord etc as well as new such as Expo Exact).
Great work @e2e team!
Callstack Engineers retweeted
It’s event time at @callstackio Office in Wrocław. @AITinkerers meetup today and @bot hackathon tomorrow!
Callstack Engineers retweeted
this. what we do at Callstack:
+ create our own evals
+ train our own model @apex__ai
+ write everything down
+ self-host open models for 250+ employees
+ build our own software factory
+ use open-source tools like @agent_device
you can do it too. DMs open, happy to share more
Own your intelligence.
Anyone that opposes this has something to sell you (perhaps your own intelligence back to you.)
Local models need to continue proliferating. The “absolute unit” massive models may be out of reach for now locally, so your best option is to, indeed, keep your options open. Own your harness, data, connections, runtime: your agents. Embrace open source.
Callstack Engineers retweeted
hey @vercel should we join forces with @callstackio for full agent-family?
Callstack Engineers retweeted
Introducing Simlock: a free, open-source tool that turns your machine into a simulator cloud that manages itself, so every coding agent gets its own iOS or Android device, simulator or real phone.
github.com/callstackincubato…
You can now use Simlock in T3 Code. Simlock is a gateway that lets you connect multiple machines to a unified API that your agents can request leases from when they need to test mobile stuff.
Works for both Android and iOS and is a great alternative to EAS Simulators if you happen to have some spare compute laying around!
Callstack Engineers retweeted
How has your experience with Simlock been so far? I know Windows support is currently missing but is on the way. Is there anything else that’s missing?
Callstack Engineers retweeted
I measured Hermes bundle sizes across 78 React Native apps:
→ iOS: 14 MiB median (49 apps)
→ Android: 18.8 MiB median (64 apps)
→ no correlation with store ratings
The largest iOS bundle was 122 MiB. Its app had a 4.68/5 rating.
Do whatever you like with this information
Callstack Engineers retweeted
React Native 0.88 is now available!
This release switches to a web-based event dispatching model, adds variable fonts support, SceneDelegate on iOS, and ArrayBuffer support for Android TurboModules. And it's another non-breaking major release.
reactnative.dev/blog/2026/10…
Callstack Engineers retweeted
SDK 58 is out 🙌
This SDK is built for iOS 27. Apps on SDK 58 will be ready for Duo on day one 📖.
The release also includes App Intents for Siri, 2x faster clean Android builds, faster Expo modules, and a CLI built for your coding agent.
Changelog: expo.dev/changelog/sdk-58
Upgrade: 𝚗𝚙𝚡 𝚎𝚡𝚙𝚘 𝚒𝚗𝚜𝚝𝚊𝚕𝚕 𝚎𝚡𝚙𝚘@^𝟻𝟾.0.0 --𝚏𝚒𝚡
Callstack Engineers retweeted
react-native-arrangement-view 0.4.0 is out 🧩
→ New <HingeObserver /> API to enable reading hinge state anywhere in your tree
→ New useHingeSelector() for observing a derived value from the hinge state
→ New `isOverlapping` key in useArrangementLayout()
And a new example page showcasing Tent posture ✍️
Callstack Engineers retweeted
We’re at Vercel Ship 26 in SF with @callstackio. Reach out if you’re in town and want to grab a coffee and talk about agentic infra
Callstack Engineers retweeted
agent-device just crossed 1M monthly downloads and 5k stars! 🎉
I have so much fun shipping this project to you, learning new things every day. hope you find it helpful
Callstack Engineers retweeted
Who's testing the code your agents write? @SzymonRybczak of @TesterArmy explains AI testing for web and mobile apps, including test plans built around each pull request.
Callstack Engineers retweeted
We trained Apex for React Native. It landed #2 at fixing web React.
Callstack's Apex is tied #5 overall on @aidenybai's ReactBench. React Native tuning carries over to the web.
Try it on Vercel AI Gateway or apex.callstack.com
Callstack Engineers retweeted
There’s a cheap coding model that’s SOTA in React Native and Next.js available on AI Gateway.
It’s called Apex.
vercel.com/ai-gateway/models…
Callstack Engineers retweeted
First model from Poland on Vercel AI Gateway. Let's go @callstackio! 🇵🇱
vercel.com/ai-gateway/models…
Callstack Engineers retweeted
Introducing Mobile Dev: full mobile dev tooling right in your Codex app ✨
