Choose File > Collect and Save, collect both regular external files and files from Bitwig packages, then back up the whole project folder. A Bitwig project is a folder: the .bwproject file plus subfolders Bitwig creates as you work (samples, recordings, plugin-states, master-recordings, bounce). Audio you dragged in from a sample library stays where it was until you collect it, so copying the folder without Collect and Save leaves those samples behind.

Check what is missing before you back up

Open the Project panel (the file icon in the window footer) and look at two tabs:

• Files lists every audio file the project uses. A blank square means the file is inside the project folder, yellow means it is external, red means it is missing. Find All searches a folder for every missing file, and the Collect and Save button at the bottom copies the external ones in. Delete Unused clears files the project no longer uses.
• Plug-ins lists every plugin. Yellow is a version conflict (the installed plugin is older than the one the project was saved with), red is missing. Collect and Save never copies plugins: the other machine needs them installed.

When both lists are clean, copy or zip the project folder.

Version a project

Use File > Save As with a numbered name (song v3) before a big change, inside the same project folder so the versions share its samples. For a project you send out, zip the folder after Collect and Save and keep that zip as the snapshot.

Share a project, with Bitwig users or anyone else

A Bitwig user needs the collected project folder, the same Bitwig version or newer, and your plugins. Someone on Studio One, Cubase or another DAW that reads the open DAWproject format can open File > Export DAWproject. A .dawproject holds the project's generic data: tracks, timing, audio, notes, automation, tempo and time signature, and the full state of VST2, VST3, AU and CLAP plugins. Clip Launcher clips and scenes do not come across to Studio One, and Bitwig's own instruments and effects (Polymer, The Grid) do not exist in other DAWs, so bounce those tracks to audio first.

Export stems for mixing or mastering

1. Choose File > Export Audio.
2. In Tracks, tick each track to export; each one is written as its own file. Group tracks show as folders you can tick or open. Tick Project Master as well if you want the full mix.
3. Set the Time Range to the full Arrangement so every stem starts at the same point.
4. Under Options, tick Pre-fader to ignore mixer volume automation, which Bitwig recommends for stems. Turn on Dither when you export below the project's bit depth.

Only the Arranger timeline is exported, not Launcher clips. Record a launcher performance into the arrangement first.

Doing it in Aden

Aden's desktop app syncs Bitwig projects, and plays them in the browser through the DAWproject format Bitwig exports.

• Your projects, listed. The desktop app finds .bwproject files on your disk and lists them on Home.
• Sync the project folder to a track (Max plan). Every save is pushed. A collaborator clicks Pull for the latest files; a pull never overwrites their local edits, it saves the incoming file as a versioned copy beside theirs. Every synced file keeps its version history, downloadable from the track's Project files page.
• A check before you send. Send as a transfer zips the project folder into a link that expires in 30 days, and tells you to collect your files first when it holds little more than the .bwproject.
• Export a DAWproject beside it to hear it. Aden does not read the .bwproject itself. Save a .dawproject into the synced folder and the Project files page reads it: tempo, tracks, devices with their plugin format, clips and notes. Press play for a sketch of the arrangement with your samples; third-party instruments get a stand-in sound. Without a DAWproject, it plays the bounce linked to the project, or the track's final version.
• Edit and record together. With a DAWproject, move or delete clips with everyone on the page and Save writes them into the .dawproject as its next version. Vocal takes recorded in the browser are written into it as clips on a new track, at the bar you sang them.
• Feedback on the bounce. Export the mix and the desktop app notices it: named after a track you have, it offers it as that track's next version. Send a share link and people comment at a timestamp or on a section of the waveform, with no Aden account needed on a link with comments turned on. Send for review asks them to approve it or request changes, and Compare flips between mixes at the same playhead.
• Stems on a version. Upload your exported tracks to the version's Stems tab to play them together under the mix.
• Aden inside Bitwig. The desktop app installs Aden as a VST3 and CLAP plugin on macOS and Windows. Put it on the master to see the track's notes, lyrics and session without leaving Bitwig.

Sources: Bitwig Studio User Guide, The Project Panel, Working with Projects and Exporting, Exporting Audio, Exporting Projects, Bitwig, DAWproject FAQ. See also how other DAWs version projects.