ForceNetflix4K is an open-source browser extension for Chromium and Firefox that spoofs browser resolution, User-Agent, and media capability reporting to unlock 4K Ultra HD streaming profiles on Netflix.
Important
What This Extension Does (and Does NOT) Do
Spoofing browser metrics is ONLY ONE of several strict prerequisites Netflix enforces to deliver 4K streams. This extension bypasses browser-side screen dimension and capability checks, but it cannot bypass hardware or DRM requirements (such as HEVC GPU decoding or HDCP 2.2 protection).
Warning
Possible UI Layout Glitches
Because the extension forces the browser to report a 4K UHD screen (3840×2160) and a fixed device pixel ratio, Netflix's web interface (navigation bars, video carousels, and thumbnail cards) may appear slightly scaled or display minor visual layout glitches on smaller displays. Video playback in fullscreen or inline player operates normally.
To stream Netflix in 4K Ultra HD, your environment must satisfy all of the following conditions. Here is how ForceNetflix4K interacts with them:
| Requirement | Description | Bypassed by ForceNetflix4K? |
|---|---|---|
| 💳 Netflix Premium Plan | An active subscription tier supporting Ultra HD (4K). | ❌ No (Account level) |
| 💻 Hardware / GPU & HEVC Codec | GPU acceleration supporting HEVC (H.265). (On Windows, Microsoft's HEVC Video Extensions app (€0.99 on the Microsoft Store) is required if not pre-installed by your OEM). | ❌ No (Hardware / OS level) |
| 🔐 HDCP 2.2 Display Chain | Graphics card, monitor, and cables must all support HDCP 2.2. | ❌ No (DRM / OS level) |
| 🖥️ 4K Screen / Viewport (3840×2160) | Screen resolution reported to the browser must be 4K UHD or scaled high DPI. | ✅ YES (Spoofed by Extension) |
| 🌐 Supported Browser & User-Agent | Edge/Safari or Windows PlayReady browser detection for 4K profiles. | ✅ YES (Spoofed by Extension) |
| 📼 MediaCapabilities & Codec API | Browser reporting supported: true for 4K HEVC/AV1 video decoding. |
✅ YES (Spoofed by Extension) |
| Browser | Status | Notes |
|---|---|---|
| Google Chrome | ✅ Supported | Working on Windows 10/11 with HEVC hardware decoding. |
| Microsoft Edge | ✅ Supported | Native PlayReady DRM support. |
| Brave | ❌ NOT Supported | Brave's built-in Shields and anti-fingerprinting protections interfere with spoofing and block Netflix 4K PlayReady profile negotiation. |
| Firefox | Firefox lacks OS-level PlayReady hardware DRM integration required by Netflix for 4K streams. |
When visiting netflix.com, the extension injects scripts into the main document context at document_start to perform the following:
- User-Agent & Platform Spoofing: Spoofs the browser environment to report as Microsoft Edge on Windows 10, triggering Netflix's PlayReady 4K video profile selector.
- Screen & Viewport Dimensions: Intercepts
window.screen,Screen.prototype,innerWidth,innerHeight, anddevicePixelRatioto present a 3840×2160 (4K UHD) display to Netflix scripts. - Media Query Interception: Wraps
window.matchMediato return positive matches formin-width,min-device-width, andmin-resolutionqueries up to 4K. - MediaCapabilities & MediaSource Overrides: Hooks
MediaCapabilities.prototype.decodingInfoandMediaSource.isTypeSupportedso Netflix's player detects full support for 4K UHD resolutions and modern codecs (hev1,av01,vp09).
A common reason users fail to get 4K—even when using this extension—is HDCP (High-bandwidth Digital Content Protection) compliance across multi-monitor setups.
Warning
How HDCP Multi-Monitor Enforcement Works:
Netflix uses hardware-level DRM (Microsoft PlayReady SL3000 or Google Widevine L1) via the operating system and GPU driver. Before serving a 4K stream, the DRM engine verifies the entire display chain.
If ANY connected monitor lacks HDCP 2.2 support (e.g., an older secondary 1080p display, a DVI/VGA adapter, or a non-compliant HDMI cable), the OS DRM system will flag the display chain as unsecure and force Netflix to fallback to 1080p or 720p. No browser extension can override this OS/DRM hardware block.
- Disable Secondary Displays During Playback:
- On Windows, press Win + P and select "PC screen only" (or select only your primary 4K display).
- Disconnecting non-HDCP 2.2 monitors from the display topology restores the secure HDCP 2.2 chain.
- Check Connectors & Cables:
- Ensure your 4K monitor is connected directly to your GPU via HDMI 2.0+ or DisplayPort 1.4+ cables rated for HDCP 2.2.
- Hardware Splitters:
- Some active HDMI 2.0 splitters/converters with EDID management can sanitize HDCP handshakes across mixed-resolution displays.
ForceNetflix4K is open-source under the MIT License, and contributions from the community are warmly welcome!
If you find a bug, have an idea for an improvement, or want to contribute code:
- Fork the repository.
- Create your feature branch (
git checkout -b feature/amazing-feature). - Commit your changes (
git commit -m 'feat: add amazing feature'). - Push to the branch (
git push origin feature/amazing-feature). - Open a Pull Request.
- Node.js: v20 or later
- npm: v10 or later
# Install dependencies
npm install
# Start development mode with hot-reloading (Chrome)
npm run dev
# Start development mode for Firefox
npm run dev:firefox
# Typecheck and lint
npm run lint
npm run typecheck
# Production build
npm run build
# Build zipped packages locally for testing
npm run zip
npm run zip:firefoxDistributed under the MIT License. See LICENSE for details.