Case study · Streaming and social viewing
Watch Party.
A real-time browser extension that lets users watch movies and shows together with synchronized playback and live chat.
- What we built
- Browser extension with real-time backend
- Stack
- React, Manifest V3, Target platform: Netflix (MVP), Node.js + Express
- Services
- Browser extensionReal-time backendUX/UI design
About the project
What is Watch Party?
This project focused on building a real-time Watch Party Chrome extension that allows users to watch Netflix movies and shows together with synchronized playback and live chat. Netflix does not provide native support for group watching with synchronization and communication. The goal was to create a lightweight, reliable extension that enables friends to join a shared viewing session instantly, stay perfectly in sync, and interact socially, without requiring user accounts or complex setup. The solution combines a Chrome extension with a real-time backend system to manage playback synchronization, party control, and messaging for up to five users per session.
Solution
A host-controlled watch party system was developed using a Chrome extension and real-time communication architecture. The host acts as the single source of truth, ensuring all playback events propagate instantly to connected users. The extension integrates directly with Netflix's player, providing synchronized playback, party management, and real-time chat, all within the browser.
Conclusion
The extension successfully delivers a synchronized, social Netflix viewing experience through a clean, real-time architecture. The project demonstrates how browser extensions can transform individual content consumption into a shared experience, enhancing existing platforms without disrupting the native user experience.
The problem
What was slowing them down.
- 01
Playback desynchronization
Playback desynchronization between users.
- 02
No centralized control
No centralized control for play, pause, or seek actions.
- 03
Lack of built-in chat
Lack of built-in chat for shared viewing.
- 04
Poor handling of disconnects
Poor handling of disconnects during sessions.
- 05
Late joiners
Late joiners cannot align with ongoing playback. These challenges result in a broken and frustrating shared viewing experience.
The solution
What we built.
Synchronized Playback
Host-controlled play, pause, and seek.
- Non-host playback attempts automatically revert
- Periodic resync to prevent playback drift
Host Controls
Start and end party sessions.
- Pause or resume playback for all users
- Force resync to align all participants
Party Lobby
Pre-play lobby with user list.
- "Ready" status for guests
- Host-only start control
- Built-in chat before playback begins
Party Management
Shareable party link for easy joining.
- No authentication required
- Display names for participants
- Maximum of 5 users per party
Join-Late Synchronization
New users automatically sync to the current playback time.
- Seamless entry without restarting content
Connection Handling
Automatic resync on user reconnection.
- Temporary host disconnect pauses playback
- Party ends cleanly if host leaves
In-Party Chat
Real-time text chat during playback.
- Enables social interaction without leaving Netflix
Results
What changed.
Viewers
Perfect Playback Sync
Reliable real-time synchronization.
Improved Engagement
Chat and shared viewing increased interaction.
Low Barrier to Entry
No login or onboarding friction.
Robust Handling
Disconnects and late joins managed gracefully.
Scalable MVP
Architecture ready for future platform expansion.
Key challenges
The hard parts, and how we solved them.
Playback drift
Periodic resync and host authority model.
Late joins
Automatic timestamp synchronization.
Conflicting controls
Host-only playback permissions.
Disconnect handling
Pause, resync, and clear user states.
Player integration
Reliable Netflix DOM event handling.
Tech stack
What it runs on.
- Extension Development
- ReactManifest V3Target platform: Netflix (MVP)
- Backend Development
- Node.js + ExpressMongoDBWebSockets (real-time communication)
Process
How we got there.
01Research & Discovery
Studied existing watch-party tools
02UX/UI Design
Designed a minimal overlay aligned with Netflix's interface
03Extension Development
Implemented player detection and playback controls
04Real-Time Backend
Built WebSocket-based room and sync system
05Testing & Optimization
Validated multi-user sync, reconnections, and drift prevention
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