LoopKnife

🔪 Slice, tag, and export engine-ready audio in seconds.

LoopKnife is a lightweight, zero-install interactive web utility designed for sound designers and game developers to inject seamless loop points directly into audio metadata chunks. Built entirely with Vanilla JS and the Web Audio API, it runs completely inside your browser sandbox. No installation, no server uploads, and no setup required.

Many popular game frameworks (especially RPG Maker)  require explicit, sample-accurate loop tags embedded directly inside file metadata chunks (LOOPSTART and LOOPEND) to cycle background music or ambient layers without popping.

Traditionally, achieving this means a tedious, multi-step workflow:

1. Fire up a full Digital Audio Workstation (DAW) or an external editor like Audacity.
2. Hunt down precise sample coordinate indexes manually.
3. Open a separate command-line metadata utility or use archaic tagging software to write the markers.

LoopKnife completely eliminates this friction. It brings the entire process into a single, visual drag-and-drop web deck. For standard files that just need to loop from the absolute end back to the very beginning, you can simply import and export immediately - turning a multi-step chore into a two-second click.

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🎛️ Key Features

• 🎯 Visual Precision: Drag yellow (Start) and red (End) interactive timeline boundaries over the canvas waveform, or type exact millisecond/sample metrics directly into the control deck.
• ⚡ Instant Batch Shortcuts: Instant 1-click bounds assignment for full-file looping.
• 🔒 100% Private & Local: Your audio files never leave your machine. All decoding, metadata slicing, and binary writing happen entirely client-side in your local browser tab.

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🎮 Engine Compatibility

LoopKnife handles native metadata injection for standard .wav and .ogg containers, writing tags universally recognized by:

• RPG Maker (MV, MZ, and classic iterations)
• Godot Engine
• Unity
• Unreal Engine
• Audio Middleware (FMOD, Wwise)

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⚖️ License & Open Source

LoopKnife is open-source software released under the permissive MIT License. It is completely free for both personal and commercial game development pipelines. If you use it, credit is nice, but ultimately not required.

• View the Source Code on GitHub: github.com/JDSherbert/LoopKnife

• Follow Development or Contribute: Pull requests, bug reports, and feature suggestions are highly welcomed!

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Having issues/prefer to use the web version of this tool?
Head here: https://jdsherbert.github.io/LoopKnife/

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