Convert MOV to MP4 Free Online

Convert QuickTime MOV to MP4 (H.264 + AAC) for free in your browser. Fast remuxing with no upload. Your files stay on your device.

MOV (Apple's QuickTime File Format) and MP4 are closely related containers. MP4's underlying ISO Base Media File Format was derived directly from QuickTime, which is why a .mov and a .mp4 can hold the exact same H.264 video and AAC audio streams inside — only the outer wrapper is different.

When your MOV already uses a delivery‑friendly codec like H.264 for video and AAC for audio (typical for many iPhones and screen recordings), GrepCut can convert it to MP4 by remuxing instead of re‑encoding. That means no extra compression step, no generation loss, and a result that is visually identical to your source.

If a MOV uses heavier production codecs such as Apple ProRes or very high‑bitrate HEVC, a traditional "convert" step in other tools usually means transcoding into H.264 with some quality trade‑off. GrepCut is designed to avoid unnecessary recompression. It will only re‑encode when strictly required for compatibility and will surface clear feedback if your browser cannot decode a specific stream.

YouTube, Instagram, TikTok, and most major social platforms recommend MP4 with H.264 video and AAC audio as the safest upload choice — YouTube's own upload encoding guidelines name MP4 (H.264 video, AAC‑LC audio) as the preferred container — even though they technically accept MOV as well. Starting from MP4 usually results in faster uploads, fewer errors, and more predictable final quality once the platform re‑encodes your video for streaming.

On desktop and mobile, MP4 is also the more universal option. A single H.264/AAC MP4 exported from GrepCut will play in default players on Windows and Android, in mail clients, in messaging apps, and in embedded HTML5 video tags without extra plugins.

By default, modern iPhones record video as HEVC inside a .mov container — this is Apple's "High Efficiency" camera setting (Settings → Camera → Formats), while switching to "Most Compatible" records H.264 instead. The HEVC files look perfect on Apple devices, but they can be difficult to play on older Windows machines, low‑end Android phones, or in some browsers.

By turning those camera‑original MOV files into H.264/AAC MP4, you keep the look of your footage while avoiding the typical "cannot open file" or "codec not supported" messages outside the Apple ecosystem. GrepCut is optimized for these real‑world iPhone and Mac clips.

The QuickTime File Format that Apple published in 2001 became the literal foundation of the ISO Base Media File Format (ISO/IEC 14496‑12) that underpins MP4. Under the hood, both structures are built from nested "atoms" or "boxes" describing tracks, timestamps, and codecs, which is why lossless container swaps are even possible.

Many so‑called "online converters" actually re‑encode every video on their servers, even when a simple remux would be enough. That wastes upload bandwidth, takes longer, and applies an extra lossy compression step. Tools like GrepCut take a more surgical approach: keep the original bits when the codecs already match what MP4 expects.

WebCodecs is one of the newer browser APIs (shipping in Chromium browsers from 2021, with Firefox and Safari following more recently) that makes serious, low‑latency video processing in JavaScript feasible. Combined with WebAssembly builds of battle‑tested media libraries, it lets a web page behave much more like a native editor or transcoder — with the privacy benefit that your raw footage never leaves your machine.