Compress Video — Reduce File Size
Shrink a video to fit a Discord, email or WhatsApp limit, or just pick a quality level. No upload, works offline, no watermark. Your video is compressed on your device — which is private, but slower than a cloud service for big files.
Runs entirely in your browser — your video is never uploaded.
- No upload Your video never leaves your device — it is processed locally.
- Works offline After the first load it runs with no internet connection.
- No size or daily limits No file caps, no paywalls — only your device memory.
- Private & safe Skip sketchy upload sites; nothing is sent to a server.
How it works
Compression is handled by ffmpeg compiled to WebAssembly and run inside your
browser. In Quality mode it re-encodes the video to H.264 with a constant-quality setting
(-crf) and re-encodes audio to AAC at 128 kbps, producing a smaller MP4 whose exact
size depends on the footage. In Target-size mode it first reads the video’s duration in the
browser, calculates a video bitrate that should land near your chosen megabyte target (reserving
room for audio and a small safety margin), then runs a two-pass H.264 encode — a first analysis
pass followed by the real pass — to hit that size accurately. Every step runs on your device, so
the video is never uploaded. The first run downloads the engine once (about 9 MB), then caches
it for offline use.
How to compress a video
- Choose a video with the drop zone above, or drag a file onto it.
- Pick Just make it smaller with a quality level, or a size limit like Discord, email or WhatsApp.
- Optionally open Advanced options for CRF, resolution, encoder speed, audio bitrate or two-pass.
- Press Compress video and wait — re-encoding takes time. Then click Download.
This is the slowest tool here because it re-encodes the whole video on your device. A few-second clip is quick; a long or high-resolution video can take several minutes, particularly on a phone. Trimming first is the easiest way to speed it up.
Why compress locally instead of on an upload site
Online compressors upload your full video to a server, squeeze it there, and give you a link. That can feel faster on a strong connection, but it hands your private footage to a third party, often caps the file size or length, and sometimes adds a watermark. Compressing in your browser keeps the video entirely on your machine — nothing is uploaded — at the honest cost of speed, since your device does the encoding instead of a server farm. It also avoids the safety concerns around free file sites: in March 2025 the FBI warned that some free online converter sites were being used to spread malware, so on-device processing is the safer choice.
| Local (this site) | Typical cloud tool | |
|---|---|---|
| Upload required | No | Usually |
| File-size caps | None (device memory) | Common |
| Works offline | Yes, after first load | No |
| Files stay private | Yes — never sent | Sent to a server |
Common uses
Getting a clip under Discord’s 10 MB free limit or 50 MB Nitro limit, shrinking a video to fit an email attachment cap, squeezing a recording down for WhatsApp, or simply reducing a bulky phone video before backing it up or sharing it. For long videos, trimming to just the part you need before compressing keeps both the file size and the encode time down.
More video & audio tools
Frequently asked questions
Why is compressing slower than other tools here?
Compression is the one tool that re-encodes every single frame of your video, which is heavy work — and ffmpeg runs here as single-threaded WebAssembly rather than native multi-core code. A short clip can take a minute or two; a long or high-resolution video can take several minutes, especially on a phone. This is an honest trade-off: you get full privacy and no upload, at the cost of speed. For a big file, trim it down first or use a desktop app if you need raw speed.
What is the difference between “just make it smaller” and a size limit?
“Just make it smaller” uses a constant-quality setting (CRF): you pick how much quality to keep and the file lands at whatever size that produces — simple and reliable, and it does not need to know the video length. Choosing a size limit (Discord, email, WhatsApp) aims for a specific number of megabytes by calculating a bitrate from the video’s duration and doing a slower two-pass encode to hit it accurately. Use the quality option for a quick shrink, and a size limit when there is a hard cap you must fit under. Advanced options expose the CRF value, resolution, encoder speed, audio bitrate and the two-pass target directly.
Will it exactly hit the size I ask for?
Target-size mode gets close — usually within a few percent — but it is an estimate, not a guarantee, because a video’s compressibility varies with its content. The tool reserves room for audio and adds a small safety margin, but a very busy, detailed clip can land slightly over. If it does, choose a smaller target or trim the clip and try again.
Is my video uploaded to compress it?
No. Compression runs entirely in your browser with ffmpeg compiled to WebAssembly. Your file is read into memory on your own device, re-encoded there, and the smaller MP4 is written locally. Nothing is sent to a server and no copy is stored online — which is exactly why it can be slower than a cloud service but is far more private.
How small should I make a video for Discord, email or WhatsApp?
Discord allows 10 MB uploads on a free server and 50 MB with Nitro; many email providers cap attachments around 25 MB; WhatsApp limits videos to roughly 16 MB. The presets target these common limits, and a custom field lets you enter any size in megabytes. Picking a target a touch below the real limit leaves a margin so the upload is accepted.
Does it work offline?
Yes. The site is a Progressive Web App, so it works without a connection after the first visit, and the ffmpeg engine is cached after its one-time download so compression keeps working offline.
All processing happens on Video Tools entirely within your browser. Videos are never uploaded to a server.