Make any video fit. Privately.
Slimcast shrinks your video to an exact size target right in your browser. Nothing uploads, nothing waits on a server, and your video never leaves your device.
How it works
Three steps, all on your device
Drop your video
Drag a clip onto the page, or pick several at once. It loads straight into your browser. There is nothing to upload and no account to make.
Pick a target size
Tap a preset for Discord, Email, or WhatsApp, or type any number in MB. Slimcast reads the clip's duration and computes the bitrate to land just under your limit.
Compress and download
Watch the live progress bar and the final reduction. Download a web-optimized MP4, or download all of them when a batch finishes.
Everything Slimcast does
An exact-size compressor that never uploads
Target-size encoding, presets, batch processing and a clean MP4 out — all running locally in your browser.
Exact target-size compression
Pick a size. Land just under it.
- Choose a target in MB and Slimcast computes the right video bitrate
- Uses your clip's duration to land the output just under the limit
- Hit a hard size cap on the first try, no guess-and-check
- Rate control with maxrate and bufsize keeps the file inside the target
Presets and custom targets
One click for the platforms you use.
- Discord (10 MB) and Discord Nitro (50 MB) presets
- Email (25 MB) and WhatsApp (16 MB) presets
- Custom MB field for any number you need
- Each platform page pre-selects the matching preset
Batch with per-file progress
Many videos, one queue.
- Drag-and-drop or select multiple videos at once
- Each file gets its own row with input size and live progress bar
- See percentage, output size, and percent reduction per file
- Per-file Download buttons, plus download-all when several finish
Sequential or parallel modes
Compress your way.
- Run files one-at-a-time in sequence
- Or compress all queued files at once in parallel
- Switch modes to match your machine and your queue
- Live progress for every file either way
100% private and local
Your video never leaves your device.
- Compression runs in your browser via ffmpeg.wasm (WebAssembly)
- No upload, no server, no account
- Works best in a Chromium-family browser over HTTPS (uses SharedArrayBuffer)
- Privacy-friendly analytics only
Web-optimized MP4 output
Clean files, ready to play.
- H.264 / libx264 video with AAC audio
- +faststart so playback begins instantly
- Encoded with a fast veryfast preset
- Rate control tuned to respect your size target while preserving quality
Handles big inputs
Built for large clips.
- Accepts videos up to about 1 GB
- Soft Large warning past roughly 500 MB
- Very large clips are bounded by your browser's available memory
- No server limits to wait on
Free, no sign-up
Just drop a video.
- No account and no email required
- No watermark on your output
- Nothing to install
- Same private, in-browser promise as our sibling SlimDoc
Why Slimcast
Private by design, not as a setting
Your video stays on your device
Online converters upload your file to a server, process it there, and send it back. Slimcast does everything in your browser. The video never leaves your machine, so there is nothing to upload and nothing to wait on.
An exact size, not a guess
Most tools give you a quality slider and hope. Slimcast works backward from your target: it reads the clip's duration and computes the bitrate to land just under your MB limit, so it fits the first time.
Made for the places you share
Discord, Discord Nitro, Email, and WhatsApp presets are one click away. Each platform page pre-selects the right limit, so you can drop a clip and download a file that fits.
Real output, real control
You get a web-optimized MP4 with H.264 video, AAC audio, and +faststart for instant playback. Run files one at a time or all at once, and watch the reduction on every file.
FAQ
Questions, answered
Is my video uploaded anywhere?
No. Compression runs entirely in your browser through ffmpeg.wasm. Your video never leaves your device, there is no server, and there is no account. We use privacy-friendly analytics only.
How does it hit an exact file size?
You pick a target in MB. Slimcast reads your clip's duration and computes the right video bitrate to land the output just under that target, using rate control (maxrate and bufsize) so the file respects the limit. That is how it fits on the first try.
Will I lose quality?
Some, since compression trades bitrate for size. Slimcast spends your target budget as efficiently as it can with libx264 and tuned rate control. The smaller the target relative to the clip, the more visible the trade-off.
What formats and browsers are supported?
Slimcast outputs a web-optimized MP4 (H.264 video, AAC audio, +faststart). It works best in a Chromium-family browser over HTTPS, because it relies on SharedArrayBuffer for in-browser processing.
Can I compress several videos at once?
Yes. Drag-and-drop or select many files. Each gets its own queue row with input size, a live progress bar, percentage, output size, and percent reduction. Compress them one-at-a-time or all-at-once, with per-file Download buttons and a download-all when a batch finishes.
How big a file can I compress?
Slimcast accepts videos up to about 1 GB, with a soft Large warning past roughly 500 MB. Because everything runs locally, very large clips are bounded by your browser's available memory.
What does it cost?
Slimcast is free. No sign-up, no account, no watermark, and nothing to install.
How is this different from online converters?
Online converters upload your video to their servers to process it. Slimcast does the work in your browser, so your file stays on your device, there is no upload wait, and you target an exact size instead of a vague quality setting.
Got a video that's too big?
Drop it in and download one that fits — nothing uploaded, no sign-up.