![[Open Source] BrowserSync — Realtime Multi-Browser Synchronization Engine (C# & Python)](https://media2.dev.to/dynamic/image/width=1200,height=627,fit=cover,gravity=auto,format=auto/https%3A%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Farticles%2F135ge1horm65o3jtx0f7.png)
I just open-sourced a project I’ve been working on called BrowserSync, and I’d love to share it with anyone interested in automation, testing, or browser internals.
The motivation came from a recurring workflow bottleneck: whenever testing responsive layouts or running multi-instance workflows, manually repeating the exact same clicks, scrolls, and form inputs across multiple screen sizes is tedious. I wanted a lightweight tool where interacting with one Master browser instantly mirrors every single user action across multiple Slave browsers in real time with near-zero latency.
What BrowserSync solves:
Responsive & Cross-Screen Testing: Open multiple viewports simultaneously (Desktop, Tablet, Mobile). Any mouse move, click, scroll, or input on the Master window propagates across all Slaves in real time, making layout breakages immediately visible.
Multi-Instance Automation: Control multiple Chromium sessions concurrently without installing browser extensions or relying on heavyweight proxy tools.
Interactive Live Demos: Present and interact on one screen while auxiliary displays reflect every gesture accurately and smoothly.
Technical Highlights:
Dual-Stack Implementation: Fully implemented in both C# (.NET 9) and Python 3 (Asyncio & WebSockets), each backed by automated test suites.
Direct Chromium communication over Chrome DevTools Protocol (CDP) with zero extension overhead.
High-fidelity synchronization for real-time Canvas drawing, mouse dragging, form controls, and multi-tab switching.
Full support for complex IME text input, carets, and text selections.
Resilient recovery mechanism (Event Journal Replay) that prevents stream dropouts during network hiccups.
The complete codebase, documentation, and benchmark test page are available on GitHub: 👉 https://github.com/vinzh05/BrowserSync
You can clone the repo and run Start-BrowserSync-CSharp.bat (or Start-BrowserSync-Python.bat) to test it out locally with a single click. Feedback, PRs, and Issues are warmly welcome — especially from developers and QA / Automation Test engineers. If you find the project useful, a Star on GitHub would be greatly appreciated!
Thanks everyone!
