📖 What is an AUP File?
An AUP file is an Audacity project file, the saved session from the free audio editor Audacity. It uses the .aup extension, and here is the part that surprises people, it is not an audio file. It holds instructions, not sound.
Rather than storing the recording itself, an AUP file is a plain-text list written in XML that tells Audacity how to rebuild your project, which pieces of audio to load, where each clip sits and what edits and effects to apply. The actual sound lives separately, in a companion folder.
That design is why an AUP on its own will not play. Think of it as a recipe rather than the meal. The recipe is short and readable, but you still need the ingredients, the audio data in the folder beside it, for the project to come together.
Key Characteristics
- An Audacity session, saved to disk
- Not an audio file, a set of instructions
- Written in XML, plain and readable
- Needs its folder, where the sound lives
Good to Know
- The legacy format, replaced by AUP3
- Opens only in Audacity, no other app
- Export to get audio, such as MP3
- Keep the pair together, file and folder
⚡ Quick Facts
| File Extension | .aup |
| Full Name | Audacity Project File |
| Category | Audio project session |
| Created By | Audacity, the audio editor |
| Format | Plain-text XML |
| Contains Audio | No, it references it |
| Companion | A matching _data folder |
| Replaced By | AUP3, from Audacity 3.0 |
| Opened By | Audacity only |
| Related Extensions | .aup3, .au, .wav, .mp3 |
🎧 Why It Is Not Audio
The single most useful thing to understand about an AUP is the split between saving a project and exporting audio. They sound similar but do very different jobs.
Because an AUP only points to audio, no media player and no general converter can turn it into sound on its own. The instructions mean nothing without Audacity to read them and the audio data to act on. This is also why renaming an AUP to .mp3 does nothing useful, there is no audio inside to rename, and why the so-called AUP to MP3 converters found online cannot work on the file alone.
🗂️ The _data Folder
Every AUP file has a partner, a folder with the same name ending in _data. If your project is song.aup, its folder is song_data, and the two belong side by side in the same location.
Audio Blocks
The folder holds many small block files, the real segments of sound the project uses.
The AUP Links Them
The project file stitches those blocks into the clips and tracks you hear.
Names Must Match
The file and folder base names have to agree, or Audacity cannot find the audio.
Move Them Together
Copy or send both as a pair, since one without the other is incomplete.
🔤 AUP vs AUP3
In 2021, Audacity 3.0 changed how projects are saved, introducing the AUP3 format. The difference solves the biggest headache of the old design.
| Point | AUP | AUP3 |
|---|---|---|
| Separate _data folder | ✓ yes | ✗ no |
| Everything in one file | ✗ no | ✓ yes |
| Can break if folder is lost | ✓ yes | ✗ no |
| Audacity version | 2.x and earlier | 3.0 and later |
AUP3 packs the whole project, audio and all, into one single file, so there is no folder to lose and no project to break. Audacity 3 still opens your old AUP projects and converts them to AUP3 as it does. Once saved that way, though, a project will not reopen in versions before 3.0.
📂 How to Open an AUP File
Opening an AUP means opening it in Audacity, the only program that reads the format. The steps are short, and the free software runs on Windows, Mac and Linux.
Get Audacity
Download and install Audacity, which is free and open source, if it is not already on your computer.
Keep the pair together
Make sure the AUP file and its matching _data folder sit in the same place before you start.
Use File then Open
In Audacity, choose File then Open and pick the AUP. The project loads with your tracks and edits in place.
🔄 Getting Audio Out
To end up with a file you can play or share, an MP3 or a WAV, you export from the project rather than convert the AUP directly. Audacity does this in a few clicks.
Open the project
Load the AUP in Audacity with its _data folder present, so all the audio is available.
Choose File then Export
Pick Export and the format you want, such as MP3 or WAV, then set a name and location.
Save the audio
Audacity writes a standard audio file from your project, ready to play anywhere or send on.
🛠️ If It Will Not Open
Most trouble with an AUP traces back to the link between the file and its folder. A few checks clear up the common cases.
| Missing _data folder | If the folder is gone or misplaced, the project opens empty or errors. Put the matching _data folder back beside the AUP. |
| Renamed file or folder | Audacity pairs them by name. If either was renamed, restore the matching base names so they line up again. |
| No Audacity installed | Nothing else opens the format. Install the free Audacity, then open the project from inside it. |
| Very old project | A project from Audacity 1.x may need opening in 2.x first, then saving, before a current version will take it. |
♻️ Recovering a Lost Project
If Audacity crashed or closed before you saved, the work is often not gone. What you can get back depends on what survived on disk, and there are a few routes to try.
| Automatic recovery | After a crash, reopening Audacity usually triggers its automatic crash recovery, a dialog listing the projects it can restore. Choose to recover, and it loads the waveforms so you can save each one properly. |
| The temporary folder | If a project was never saved, Audacity keeps working data in a SessionData temporary folder. You can import the audio it holds and rebuild a project from there. |
| Only the _data folder left | If you still have the _data folder of blocks but lost the AUP, you can import those raw pieces as audio. Note this recovers the unedited sound, not your clip and track layout. |
🔀 Related Formats
AUP sits among the Audacity and audio formats you meet alongside it.
.aup3 | The newer Audacity project format, a single self-contained file with no separate folder. |
.au | The small block files inside the _data folder, each a segment of the project's audio. |
.wav | A standard lossless audio file, a common export target that plays everywhere. |
.mp3 | A compressed audio file, the usual choice for sharing a finished recording. |
.flac | A lossless compressed audio format, useful when you want quality at a smaller size. |
❓ Frequently Asked Questions
Open it in Audacity, the free audio editor that created it, since no other program reads the format. First make sure the AUP file and its matching _data folder are together in the same place. Then, in Audacity, choose File and Open and select the AUP. The project loads with your tracks, edits and effects in place. Audacity runs on Windows, Mac and Linux, so the same steps work everywhere.
An AUP file is an Audacity project file, the saved editing session from the free Audacity audio editor. It is not an audio file. Instead of holding sound, it is a plain-text XML file that records how to rebuild your project, which audio to load, where clips sit and what edits to apply. The actual audio lives in a separate _data folder beside it, and the two work only as a pair.
Because an AUP is not an audio file, so a media player has nothing to play. It only stores instructions that point to audio held in its _data folder. To hear the project, open it in Audacity, which reads those instructions and loads the sound from the folder. To get a file that plays anywhere, export an MP3 or WAV from Audacity rather than trying to play the AUP itself.
There is no direct converter, because the AUP holds no audio to convert. Instead, open the project in Audacity with its _data folder present, then choose File, Export and pick MP3. Set a name and location and save. Audacity builds a standard MP3 from your project. The same route produces a WAV, FLAC or other audio file. This export step is the only reliable way to get playable audio from a project.
It is where your project's audio actually lives. The folder shares the AUP's name with _data added, so song.aup pairs with song_data. Inside are many small block files, the real segments of sound, and the AUP links them into your clips and tracks. The file and folder must stay together with matching names. If the folder goes missing, the project has no audio to rebuild from.
No. Deleting the _data folder removes all the audio your project relies on, leaving an AUP that cannot rebuild any sound. The AUP itself is only a small list of instructions and holds none of the recording. If you want to free up space but keep the work, export an audio file such as WAV first, and only then decide what to keep. Losing the folder means losing the project's sound.
AUP is the older format, which keeps a small project file alongside a separate _data folder of audio. AUP3, introduced with Audacity 3.0 in 2021, packs the whole project, audio included, into one single file. That means no folder to lose and no project to break by moving files. Audacity 3 opens old AUP projects and saves them as AUP3, though once saved that way they will not reopen in Audacity 2.
No. The Audacity project format is read only by Audacity, so no other audio app or general converter opens it. This is because the AUP is a set of editing instructions tied to Audacity's own way of storing audio in the _data folder. If you only need the sound rather than the editable project, ask whoever sent it to export an MP3 or WAV, which any player opens.
Sending the AUP alone leaves out all the sound, so zip the AUP file and its _data folder together and send that single archive. The other person unzips both, keeps them side by side, and opens the project in Audacity. If they only need to hear the result rather than edit it, export an MP3 or WAV and send that instead, since it plays for anyone without Audacity.
An AUP itself is a plain-text XML file with no program code inside, so it carries little risk on its own and just describes a project. As always, a file from an unknown source deserves normal care. The bigger danger with AUP projects is not malware but data loss, since separating the file from its _data folder, or deleting that folder, can destroy hours of work. Keep the pair together and backed up.
Almost always the _data folder is missing, misplaced or renamed, so Audacity cannot find the audio the project points to. Put the matching _data folder back in the same location as the AUP, with the base names lined up, and reopen the project. If the folder is truly gone, the audio it held cannot be recovered from the AUP alone, which is why keeping the two together matters so much.
Yes. Current versions of Audacity open older AUP projects, including those from 2.x versions, and import them into the newer AUP3 format. Very old projects from Audacity 1.x may need a stop in a 2.x version first, saved there, before a current release will take them. Keep in mind that once a project is saved as AUP3, it can no longer be opened in Audacity versions before 3.0.
You can open an AUP in a text editor and read it, since it is plain XML, but there is little reason to edit it by hand and doing so can break the project. The file lists references and coordinates that Audacity manages precisely. Real editing, cutting, mixing and applying effects, is meant to happen inside Audacity with the project open, not by changing the instructions directly.
Reopen Audacity first. After a crash it usually shows an automatic recovery dialog listing the projects it can restore, so choose to recover and then save each one properly. If a project was never saved, Audacity keeps working data in a SessionData temporary folder that you can import audio from and rebuild. If recovery looks wrong, do not save or close the project yet, since that can overwrite what is still recoverable.
Partly. The _data folder holds the raw audio blocks, so you can import those pieces into Audacity as sound and save a new file from them. What you cannot get back this way is the project layout, since the clip positions, edits and effects lived in the missing AUP. In short, the recording can often be salvaged as plain audio, but the arrangement of your session is lost with the AUP.
Not a working one, despite what some sites claim. An AUP holds no audio, only instructions that point to sound in its _data folder, so a web tool given the AUP alone has nothing to convert. The reliable way to get an MP3 is to open the project in Audacity with its _data folder present and choose File, then Export. That builds a real MP3 from your project, which any player then opens.
📝 Summary
An AUP file is an Audacity project file, not an audio file. It is a plain-text XML session that records how to rebuild your edit, which audio to load and what to do with it, while the sound itself lives in a matching _data folder beside it. The file and folder are a pair, and separating them, or deleting the folder, leaves a project with no audio to rebuild. You open an AUP only in Audacity, the free editor that made it, using File and Open, and you get a playable file by exporting an MP3 or WAV rather than converting the AUP directly. AUP is the legacy format, replaced in 2021 by AUP3, which bundles the whole project into one single file so there is no folder to lose. Audacity 3 still opens old AUP projects and converts them. To share a project, zip the AUP and its _data folder together, or export audio if the other person only needs to listen.