Convert WebM to MP4 online

Convert WebM to MP4 online in batches. Files stay in your browser and are never uploaded or stored on a server.

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Your files stay on this device and are never uploaded.

Drop files here to convert them

Up to 5 files · 100 MB each · 250 MB per batch

Choose WebM files and convert them to MP4 together in one private browser session.

How to convert WebM to MP4

Select one or more WebM files, start the batch, then download each MP4 result or all completed files together.

This WebM-to-MP4 conversion decodes each source and encodes a new output in the selected format.

Process up to 5 files per batch, with 100 MB per file and 250 MB in total.

The conversion runs locally in your browser. NDNCI never receives, stores, or sends your files to a third party.

Audio Converter

Convert MP3 and WAV audio, or extract MP3 audio from MP4, in private browser-only batches with no uploads.

Base32 Encoder/Decoder

Encode UTF-8 text to Base32 or decode Base32 values locally.

Base64 Encoder/Decoder

Encode or decode Base64 strings.

Image Converter

Convert PNG, JPEG, and WebP images in private browser-only batches with no uploads.

Markdown/HTML Converter

Convert between Markdown and HTML in both directions.

Spreadsheet Converter

Convert CSV and XLSX spreadsheets in private browser-only batches with no uploads.

URL Encoder/Decoder

Encode or decode URLs quickly.

Image Upscaler

Upscale images 2× locally, with optional AI acceleration and browser fallbacks.

Video Upscaler

Upscale videos 2× locally, using AI and WebGPU when available with a browser fallback.

3D Model Viewer

Open 3D models locally, inspect geometry, materials and textures, then download the original files.