Trim, Compress & Convert Video
Trim clips, compress file size, change resolution, and convert between formats — all inside your browser. Powered by FFmpeg.wasm. Nothing is uploaded to any server.
Ready.
How to Use
Alfreto's Video Toolkit is a free, all-in-one video processing tool that runs 100% inside your browser. To get started, click Choose Video or drag and drop your video file into the upload area. Supported input formats include MP4, WebM, MOV, MKV, and AVI. Once loaded, the source video is previewed and its duration and file size are displayed automatically.
Choose one of the four Operations: Trim to cut a clip between a start and end time using the interactive timeline; Compress to reduce file size by adjusting CRF quality and encoding preset; Resolution to downscale or upscale to common sizes like 4K, 1080p, 720p, or a custom width/height; and Convert to change the container format (e.g. MP4 → WebM) with a choice of video and audio codec. You can combine operations by adjusting settings across multiple tabs — the tool will apply them all in one FFmpeg pass.
Click Process when you are ready. A progress bar shows FFmpeg's real-time progress. When finished, the output video is shown in the preview panel alongside file size stats. Click Download to save the result. All processing uses FFmpeg.wasm with multi-threading — everything stays on your device.
FAQ
Is my video uploaded to a server?
No. All processing happens locally in your browser using FFmpeg.wasm. Your video file never leaves your device at any point.
Which browsers are supported?
All modern browsers are supported — Chrome, Edge, Firefox, and Safari. FFmpeg runs in single-thread mode which works universally without requiring any special server headers. Processing may be slower than dedicated desktop apps, but works reliably on any browser.
How do I trim a video?
Select the Trim tab. Drag the pink handles on the timeline to choose start and end points, or type the exact times in the input fields below (format: hh:mm:ss). Then click Process.
What does CRF mean in Compress mode?
CRF (Constant Rate Factor) controls compression quality. Lower values (18–23) give better quality and larger files. Higher values (28–40) give smaller files with more visible quality loss. A value of 28 is a good balanced starting point.
Can I change resolution and convert format at the same time?
Yes. Configure options in multiple tabs — Trim, Compress, Resolution, and Convert — and they will all be applied in a single FFmpeg processing pass when you click Process.
Why does it take time on first load?
FFmpeg.wasm (~10 MB) is downloaded from a CDN (jsDelivr) on first use. Subsequent uses within the same browser session are instant because the engine is cached. The download happens once per session.
Is there a file size limit?
There is no hard limit, but very large files (over 2 GB) may run into browser memory limits. Performance depends on your device hardware. For best results, process files under 1 GB.