ARP File

What are ARP files and how to open them

Are you having problems opening an ARP file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your ARP files.

What is an ARP file?

ARP files have multiple uses, and Audition Play Data is one of them. Read more about the other uses further down the page.

Audition Play Data

We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

How to open ARP files

Important: Different programs may use files with the ARP file extension for different purposes, so unless you are sure which format your ARP file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested ten different ARP openers which you will find listed below.

Last updated: August 20, 2026

All known file formats using extension .ARP

While Audition Play Data is a popular type of ARP-file, we know of 2 different uses of the .ARP file extension. Different software may use files with the same extension for different types of data.

MIDI Arpeggiator Arpeggio

MIDI Arpeggiator Arpeggio files store full arpeggio setups created with Electronic Cow's MIDI Arpeggiator software on the Atari ST (and compatibles). They preserve all the musical data such as tracks, patterns, mixer settings, note/velocity information and play-mode options, so that the arpeggio can be resumed exactly as it was when saved.

These files are produced by the "Save" or "Save As" command inside MIDI Arpeggiator. When opened later by the same software, the internal sequencer restores the note and velocity data, pattern layout, mixer assignments (volume, pan, auxiliaries), and performance controls such as pattern-selection and looping. They are used both for continuing work and for sending setup data over MIDI so that external hardware reflects the arpeggio's state immediately on loading.

The format supports versions up through MIDI Arpeggiator v3.0: newer files include additional settings, and when older files are loaded in v3.0, missing parameters are filled in with default values. The arpeggio performance can also be exported to standard MIDI files (type 0 or type 1), but the internal file keeps more meta-data than a bare MIDI file can.

Files start with the ASCII identifier "Arp" followed by specific bytes (0x4172700400 at offset 0) which distinguish them from other file types.

Various apps that use files with this extension

These apps are known to open certain types of ARP files. Remember, different programs may use ARP files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about ARP file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.