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Video Converter

Convert videos to MP4, WebM, GIF or extract audio — runs entirely in your browser, no upload

This tool downloads a one-time ~30MB conversion engine into your browser (cached after first use), then converts entirely on your device — no files are uploaded. Best for short clips; large/long videos will take longer and use more memory.
Drop video files here
or click to browse — MP4, MOV, AVI, MKV, WebM and more · up to 8 files, 80MB each
100% Private — No Upload

Conversion runs locally in your browser using ffmpeg.wasm (open-source, WebAssembly build of FFmpeg). Your video files are never sent to any server.

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What is Video Converter?

Free bulk video converter. Convert video to MP4, WebM, GIF or extract audio as MP3. Runs entirely in your browser using WebAssembly — no upload, fully private. A free online tool that works instantly in any browser. TekPulse's Video Converter is completely free — no signup, no ads in results, and no data stored on our servers.

How to Use Video Converter Online

  1. Click "Load Converter Engine" to initialise ffmpeg.wasm (one-time download, cached after first use)
  2. Upload one or more video files (up to 8 files, 80MB each)
  3. Select the target format: MP4, WebM, GIF (max 15s), or MP3 (audio extract)
  4. Click "Convert All" — files are processed sequentially in your browser using ffmpeg.wasm
  5. Download each converted file individually when processing completes

Video Converter Formula & Calculation

H.264 CRF = 18 + (100 − Quality) × 17/100 | VP8 CRF = 4 + (100 − Quality) × 55/100 | MP3 bitrate tiers: 320k / 192k / 128k / 96k

This tool runs a real build of FFmpeg compiled to WebAssembly (ffmpeg.wasm) entirely inside your browser tab — the same conversion engine used by professional video tools, just running client-side instead of on a server. Your 0–100 'Quality' slider is mapped to the codec's native CRF (Constant Rate Factor) scale, which controls the compression-vs-quality trade-off per output frame rather than targeting a fixed file size. For H.264 (MP4), CRF runs 18 (highest quality, bigger file) to 35 (lower quality, smaller file) — note the scale is inverted: a lower CRF number means better quality. For VP8 (WebM), the usable CRF range is wider (4–59). MP3 audio extraction instead picks a discrete constant bitrate (320k/192k/128k/96k) based on your quality slider, following the standard MP3 quality tiers used by most audio software. Resolution scaling uses a Lanczos filter (scale=W:-2:flags=lanczos), a high-quality resampling algorithm that reduces the ringing/blur artifacts of simpler scaling methods.

Key Factors That Affect Your Result

  1. CRF (quality) setting — Unlike a fixed bitrate, CRF lets the encoder spend more bits on complex/motion-heavy scenes and fewer on static scenes, generally giving better quality-per-byte than targeting a flat bitrate — the trade-off is that output file size isn't precisely predictable in advance.
  2. Resolution — Downscaling (e.g., 1080p → 720p) roughly quarters pixel count (and proportionally file size) while remaining visually sharp on smaller screens/mobile — a common move to shrink files for sharing or upload limits.
  3. Format choice — MP4 (H.264) has the widest compatibility across devices and platforms; WebM (VP8) typically compresses better at the same visual quality but has more limited native support in some older software.
  4. Client-side limits — Because conversion runs in your browser's memory rather than on a server, very large or long videos can run out of available memory or take a long time — this tool is best suited to short clips.

Why Use TekPulse Video Converter?

Converts Locally via WebAssembly
Uses ffmpeg.wasm — a WebAssembly build of FFmpeg — so conversion runs on your device, not a server; a ~30MB engine downloads once and is cached
5 Output Formats
Convert to MP4, WebM, animated GIF, animated WebP, or extract audio as MP3
Batch Conversion
Convert up to 8 videos at once (80MB each), with results packed into a ZIP
Trim, Resize & Adjust Quality
Set start/end time, resolution, frame rate and quality — note that WebAssembly conversion uses real device CPU/memory and can be slow on large files

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Frequently Asked Questions

No — conversion runs entirely in your browser using ffmpeg.wasm, a WebAssembly build of FFmpeg. Your video files are never uploaded anywhere.

The tool downloads a one-time ~30MB conversion engine into your browser. Your browser caches it, so subsequent visits and conversions start instantly.

It runs via WebAssembly using your device's CPU without hardware acceleration, so it is noticeably slower than native apps. It works best for short clips and smaller files.

Animated GIF is a very inefficient format — converting a full-length video would produce an enormous file. Limiting to 15 seconds at 480px width keeps the output a reasonable size, matching standard practice across converter tools.

Some video codecs or container formats may not be supported by the in-browser engine. Try a different output format, or use a smaller/shorter clip. MP4 input files generally have the best compatibility.

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