Private video resizer # Private Video Resizer that runs on your laptop, not in the cloud No uploadNo queueWorks on any aspect ratio Resizing video usually means picking up a file, sending it to a cloud service for re-encoding, and waiting for it to come back. That model treats your footage as a payload to ship. For sensitive content this is the wrong shape: anything sent for re-encoding sits, however briefly, on someone else's infrastructure. ## Try it now The resize tool runs the same browser-local engine described on this page. [Open the Resize tool](/resize) ## Why this matters The Resize tool here re-encodes inside the browser tab. The browser reads the source bytes off your disk, FFmpeg compiled to WebAssembly produces the new dimensions, and the result is written back to your downloads folder. The intermediate frames stay in browser memory and clear when you close the tab. The practical effect is that the privacy concern goes away because the transfer goes away. Not "encrypted in transit, deleted within 24 hours", but the much simpler "never transferred." ## What you actually get #### No upload of the source file The video stays in browser memory throughout the resize operation. The Network tab of DevTools shows zero outbound requests for your media. #### Any aspect ratio, no menu of approved sizes Width and height can be anything FFmpeg accepts. Standard social presets are available; arbitrary custom sizes work too. No server-side aspect-ratio whitelist. #### No watermark on the output The free tier is the only tier. The resized MP4 contains your video at the new dimensions and nothing else. #### Letterbox and crop modes Choose how the resize handles aspect-ratio mismatches: letterbox to preserve content, or crop to fill the frame. Both run locally. ## How to resize a video privately #### 01 Open the Resize tool Click the Open button below. The Resize page loads with FFmpeg WebAssembly ready in your browser. #### 02 Drop your video Drag the source file onto the upload area. The browser reads the bytes locally; nothing uploads. #### 03 Pick a target size Choose a platform preset (TikTok, Reels, Shorts, etc.) or type a custom width and height. #### 04 Download the result Click Resize and wait for the local re-encode. The new MP4 lands in your downloads folder. ## Frequently asked questions ### How does private resizing differ from a normal online resizer? Normal online resizers upload the file to a server, re-encode it there, and send the result back. This page does the re-encoding in your browser tab against FFmpeg WebAssembly, so the upload step is skipped. The same H.264 MP4 comes out at the end, just without ever leaving your machine. ### Are there file-size limits? No imposed cap. The practical limit is your device memory and how long you are willing to wait. A modern laptop handles 1080p resize jobs up to about an hour comfortably; 4K starts to feel slow above ten minutes of input. ### Does it support the same aspect ratios as the platform presets? Yes. TikTok, Reels, Shorts, LinkedIn, and the rest are all available as one-click presets. Custom dimensions work for anything those presets do not cover. ### Will the output play on every platform? The encoder uses H.264 video and AAC audio inside an MP4 container, which is the combination that uploads cleanly to every social platform and plays on every modern device. ### What happens to the source file when I close the tab? Nothing persists past the tab session. The browser releases the in-memory buffers and the temporary OPFS scratch space (if any was used for large files) clears on the next browser cache cleanup. Privacy by architecture ## All processing happens locally in your browser, and your files never leave your device. No upload step, no server queue, no waiting. Verify in 30 seconds 1. 01`⌘⌥I` Open DevTools and switch to the Network panel. 2. 02 Filter to fetch and XHR requests. 3. 03 Drop your file in and start the tool. 4. 04 You will see the app bundle, the WASM binary on first visit, and nothing involving your file. How this works Video and audio processing runs through FFmpeg compiled to WebAssembly. Hardware decoding goes through the browser's WebCodecs API. Speech recognition runs against a Whisper model that downloads once and caches in your browser, never streamed from a third-party server. ## Related Tools and Resources #### [Resize Video](/resize) The actual resize tool, with all platform presets. #### [Resize, No Upload](/resize-no-upload) Same architecture, framed for the no-upload angle. #### [Offline Video Resizer](/offline-video-resizer) Same architecture, framed for the offline-after-first-load angle. #### [Private Video Editor](/private-video-editor) Full editor with the same browser-local model. --- Source: [https://vidstudio.app/private-resize](https://vidstudio.app/private-resize)