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Fission can crop and trim audio, paste in or join files, or just rapidly split one long file into many. It's streamlined for fast editing. Plus, it works without the quality loss caused by other editors, so you can get perfect quality audio even when editing MP3 and AAC files.

If you need to convert formats, Fission can do that too! You can rapidly export or batch convert files to the MP3, AAC, Apple Lossless, FLAC, AIFF, and WAV formats.

Key Features:

  • Edit MP3, AAC, Apple Lossless, and AIFF files with no quality loss
  • Quickly split a long audio file into smaller files
  • more...

What's New

Version 2.2.1:
  • An incompatibility with ALAC files generated by non-Apple applications like doubleTwist's "AirPlay Recorder" has been addressed.
  • Fission's Start Window is now prevented from showing if Fission was launched by opening a file.
  • We now have consistent bitrate options across all Rogue Amoeba apps, because consistency-ness is next to godliness.
  • The way Fission more...


  • OS X 10.7 or later

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Fission User Discussion

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Tiago-Calhau Member IconReview+6

No doubt is my default audio editor! I Love this app!

Reply0 replies
Version 2.2.1
Nova-Bossa-Nova Member IconReview+35


Reply0 replies
Version 2.2.0
Thinkfilm Member IconReview+17

Look, this may be rare praise indeed, but I don;t think there is a better app out there for editing audio at this price point. Rogue Amoeba sets the bar for attention to detail IMHO. I'm not a fanboy - just a user with real world needs.

Reply0 replies
Version 2.2.0
Mikael B Member IconReview+415
Mikael B

While a tad expensive possibly it is indeed the only Mac app I've found that truly can convert Flac/Cue rips to lossless formats with maintained meta data in one go. Autoadding to the iTunes library is the only obvious thing missing.

Reply1 reply
Version 2.1.4
Mikael B

Also note that Fission 2.1.3 still works on OS X 10.6! THat's what I'm using.

Gary30 Member IconReview+193

I had difficulty learning the first version of this app but eventually mastered it and liked it very much. As such I decided I didn't need to update to version 2 and skipped it. However, today I absentmindedly let MacUpdate Desktop download and overwrite the V 1.6.1 file I had. I usually hold onto downrev versions but could not find this one. Harummph.

But before I started digging around for an old file which I surely could have acquired via bit torrent, etc., or probably from the developer if i had asked, I decided to play with the new version of Fission. It turns out that it is so good I decided to enthusiastically keep it. It is really a step up from the previous version. I find it easier to work with because the modes always confused me. Also, the new FLAC support simplifies working with those files, and the new batch support is really welcome too.

Reply0 replies
Version 2.1.4
Jokyo Member IconComment+54

If this could do batch normalization I would buy it!

Reply1 reply
Version 2.1.3

The guys are really good about user suggestions, have you sent this very good idea to them?

Balanchine Member IconReview+108

Excellent little editor for quickly doing lossless trims, joins and fades. I've been using it for years to tidy up ALAC recordings made in Audio Hijack and on my iOS devices.

It's good to see that version 2 supports some extra formats for exporting - though True VBR AAC, which is my usual destination format, does not seem to be available yet, unfortunately. For that I use XLD.

Reply0 replies
Version 2.1.2
Shadokuss Member IconReview+12

Great update, smart looking, easy to use. Not 5 stars because of the hard handling with precision to level parts on a track. A vumeter or scale could be welcome when leveling db; how much db we add? +3, +4? We currently can't know.

Reply1 reply
Version 2.1.0

Definitely agree. I've paid less or as much for software that did as much (or more) and had as many features (or more) in both PC and Mac worlds. Precision is more than just zooming in on the representation of a sound wave. It has to be there in how one edits the wave.

Quortz Member IconReview+22

I don't need (or want) to work with MP3 files very often, but occasionally I need to make a minor tweak or two in MP3 tracks (dozens and sometimes hundreds) for a specific purpose: playback from an SD card or a USB thumb drive on a Bosch PowerBox. The PowerBox will only play MP3 or WAV files from SD cards or thumb drives, so I go with MP3. However, for whatever reason, you need at least one second of silence at the beginning of these tracks, or the PowerBox truncates a small amount of audio from the beginning of each. It's just a PowerBox quirk. More often than not, music files have less than one second of silence at the beginning, and sometimes almost none. So, I need to go through these files and insert silence as necessary. In the past, I would do this in Peak because it was quick and easy, but now under Lion+, Peak has a problem with MP3 files (for me at least). It insists on saving the files at low quality 128kbps, no matter what the bit rate was originally, and no matter what you set it for. And now, with the demise of BIAS, this problem will never be fixed. So, recently I decided to give Fission a spin for this task. It can do the job, but it could be much easier and faster with a few little fixes in the software. In fact, on top of some crashers I've encountered in Fission 2.0.0, this version makes this kind of task a little harder and slower than before. Let's say you have 50 tracks that need a half second of silence added to the beginning. You have a menu item to "Insert Silence," and you type the amount to insert. But that's the problem, it's only a menu choice with no keyboard command, so you are mousing/trackpadding up to the menu over and over and over. "Insert Silence" needs a keyboard command! Moving on, you insert the silence only to find it's inserted with one or two splits (depending on the playhead position). In other words, you haven't inserted the silence, you've created a separate track of silence, so the split(s) need to be removed. Here again, this is done from a menu item which has no keyboard command. Aarrgghh, more mousing to the menu bar to remove the splits that really shouldn't appear in the first place. Keyboard command please! IMO, rather than adding such splits by default, they should NOT be added by default. If the user wants to create a split, let them do so with a button or menu item (with corresponding keyboard command), but please nix the automatic splits when inserting silence. In Fission pre-2.0.0, I could somewhat work around this hassle by inserting the half second of silence, copying it, and pasting it as I moved on to other files (if you moved the playhead slightly into the beginning silence of a file, then pasted more silence, it was nicely inserted without splits). But now in v2.0.0, splits appear around pastes regardless of playhead position, so my workaround is no longer effective at preventing them, thus an extra step of going to the menu to clear them out, over and over again.

If I lost you there (i.e., you got sick of reading it), just sit down with about 400 MP3 files and use Fission 2.0.0 for the would-be simple task of adding a bit of silence to the beginning of each file, and you'll quickly see what I mean. ;-) I know other software is out there, and I don't mean to hammer on Fission, because I want to see it survive and improve. I like the dev's software, and they know what to do. The expensive, expansive (and probably dead) BIAS Peak, for example, now fails big-time for simple audio recording with Lion+. For me, it's really become unusable for recording, and Audio Hijack Pro shines in the face of it.

One last thing about Fission 2.0.0. I personally could do without the startup window. True, it gives you quick access to "Open" and "Batch Convert," and it offers a dropbox for files. However, if you'd rather hide this window and use command-O for choosing what to open, well, you can't (not me at least). This window keeps coming back to haunt me (not just on a relaunch, but even after closing the last open file). Besides, clicking "Open" in this window often causes a crash for me, but then, so does command-O. Something seems to need attention there, but nobody else has mentioned this. If this problem with "Open" hasn't bothered anyone else, maybe it's something about my own system that's conflicting, though I can't figure out what it might be, and it coincidentally appeared with Fission 2.0.0.

Reply1 reply
Version 2.0.0

Be aware that you can manually add a keyboard shortcut to ANY menu item. System Preferences -> Keyboard -> Keyboard Shortcuts -> Application Shortcuts -> +
In the window that pops up, choose the application, type the menu item *exactly* as it appears, and assign your own keystroke. Add, and Whalla.

Don't get me wrong, there's absolutely NO reason Fission shouldn't have this included already. But at least there is a way you can fix it.

Reel45 Member IconReview+2

I have been using this product for 6 years. Not only is it good at what it does but it has (until v2.0) been a pleasure to use too. That pleasure was partly due to its elegant UI, which with v2 has sadly become cruder and more childish. I would like to use some of the features in v2 but the price of having to work with that interface is a high one. I'll stick with v1.6.12 for now.

Reply0 replies
Version 2.0.0
user icon+0
Version 2.2.0
user icon+6
Version 2.2.0
user icon+45
Version 2.1.1
user icon+5
Version 2.1.0
user icon-1
Version 2.0.0
user icon+4
Fabio Milocco
Version 1.6.10
user icon+8
Version 1.6.10
user icon+0
Version 1.6.10
user icon+49
Version 1.6.10
> 4 37


Current Version (2.x)


Downloads 86,137
Version Downloads 3,060
License Demo
Date 05 Jun 2014
Platform Intel 64 / OS X
Price $32.00
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