CS
Client-Side Transcoding & Compression

Video Compressor & Format Changer

Compress video files up to 150 MB (recommended for clips under 3 minutes) and convert formats (MP4, WebM) with custom resolution downscaling and bitrate controls. Completely private — files never leave your device.

Processed locally. Your files never leave your device.

Upload Video File

Drop your video here, or browse

Supports MP4, WebM, MOV, MKV up to 150 MB

100% In-Browser Privacy • Zero Server Upload

Why Use Our Free In-Browser Video Compressor?

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100% In-Browser Privacy

Videos are processed locally via your web browser hardware. Confidential footage is never transmitted to any external servers.

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Up to 150 MB Support

Compress heavy clips up to 150 MB into lightweight formats suitable for Discord, WhatsApp, email, or fast web streaming.

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No Watermarks or Subscriptions

Export pure, clean videos without branding overlays, artificial bitrate throttles, or daily conversion caps.

Educational Guide & Technical Specifications

About the Video Compressor

Resamples video playback onto an HTML5 canvas and re-encodes the stream using the browser native MediaRecorder API, reducing file weight through configurable resolution and bitrate settings.

How to Use the Interface

1

Select Video File

Choose a video under 150 MB to load into the player.

2

Select Target Resolution & Quality

Choose 720p, 480p, or 360p scaling and adjust bitrate parameters.

3

Encode in Real Time

Click Start. Keep this browser tab open and visible while playback encodes, then download your compressed file.

Technical Format Specifications

Supported Inputs
  • MP4 (.mp4), WebM (.webm), MOV (.mov) (Browser codec dependent)
Supported Outputs
  • WebM (.webm) or MP4 (.mp4) (Host browser dependent)
Size CeilingStrictly capped at 150 MB (device RAM dependent)
Processing Boundaries & Hardware Constraints
  • •Real-Time Encoding Constraint: In-browser compression operates via canvas capture during playback; compressing a 3-minute video requires approximately 3 minutes of playback.
  • •Background Tab Throttling: Browsers throttle canvas animations to 1 fps when tabs are hidden; you MUST keep the tab active and visible until encoding completes.
  • •Browser Codec Support: iOS Safari has restrictive MediaRecorder implementations and lacks native WebM recording support; output container format depends on host browser capabilities.
  • •Memory Limits: Processing large videos (>100 MB) on low-RAM mobile devices risks silent tab crashes. Files are strictly capped at 150 MB in the interface.
Local Privacy & Data Handling
  • No video bytes ever touch a cloud transcoding server; all re-encoding occurs on your device GPU/CPU.

Common Practical Use Cases

Reducing Video for Messaging

Shrink screen recordings or phone clips below upload limits on messaging platforms.

Web Video Optimization

Encode lightweight video clips for background playback on web pages.

Frequently Asked Questions

Why does video compression take as long as the video itself?

In-browser compression captures the video stream during playback using HTML5 Canvas. Because it runs locally without heavy server-side hardware or WASM FFmpeg, encoding occurs in real time.

Why did my compression pause when I switched tabs?

Modern browsers automatically throttle background tabs to save battery and memory. You must keep the tab active and visible until encoding finishes.

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