What is the LAYOUT file format?
A .layout file is an Apple MainStage Layout file that stores the visual arrangement of screen controls within a MainStage concert or patch. It encodes the positions, sizes, display assignments, and on-screen parameter mappings of elements such as buttons, sliders, level meters, and keyboard displays that a performer interacts with during a live stage performance.
.layout files are stored inside .mainstage concert packages - macOS bundles that appear as single files in Finder. They are written in Apple's binary property list format (bplist), identifiable by the bplist magic bytes at the start of the file. Users do not open or edit .layout files directly; they are created and modified through MainStage's graphical Layout mode, which provides a drag-and-drop interface for arranging screen controls.
Because .layout files are standard binary plists, their raw structure can be inspected with the macOS command-line tool plutil -p <file>, which converts the binary data to a human-readable text representation. Hand-editing the binary file directly is impractical.
MainStage was first released in 2007 as part of the Logic Studio bundle. In December 2011 Apple unbundled Logic Studio and made MainStage available as a standalone Mac App Store purchase. The current release is MainStage 3.x, which runs exclusively on macOS. .layout files from earlier concert versions are generally forward-compatible within the MainStage 3 family.
Security & safety
RISK: LOWPlain binary property list data; not executable, no macro capability. Editing manually and reloading in MainStage could corrupt the concert layout, but there is no security risk.
Format details
in a nutshell- Various application layout/settings files - .layout extension is also used generically by many applications (IDEs, design tools) for window/panel layout persistence; no single standard.
- Nuance Power PDF / PDF Architect layout - Some PDF editors use .layout for toolbar/panel arrangement configuration.
Programs that open LAYOUT files
macOS3 apps
Apple MainStage
Paid Open the parent .mainstage concert package; switch to Layout mode (View > Layout) to see and edit the layout. 
plutil (built-in macOS command-line tool)
Built-in plutil -convert xml1 layout.layout -o layout.xml - converts binary plist to human-readable XML for inspection.
Xcode / Property List Editor (via Xcode)
Free Open the .layout file in Xcode - displays the binary plist as a readable property list tree. Technical details
deep spec| Format type | Apple binary property list (`bplist`) |
| Magic bytes | `62 70 6C 69 73 74` (`bplist` in ASCII) at offset 0 |
| Encoding | Binary, big-endian |
| Plist version | Encoded in bytes 6-7 of file: `bplist00` (most common) or `bplist01` |
| Stored inside | `.mainstage` concert package (macOS bundle/directory) |
| Purpose | Encodes MainStage screen control layout - positions, sizes, MIDI/parameter assignments per patch or concert |
| Host application | Apple MainStage - edited exclusively through the graphical Layout mode |
| Platform | macOS only |
| Typical file size | 10 KB - 500 KB |
| Inspection tool | `plutil -p <file>` (macOS built-in) converts binary plist to readable text output |
| Checksum | None - file consistency relies on the macOS file system |
| Package context | A `.mainstage` concert may contain multiple `.layout` files, one per patch or layout configuration |
| Released | 2007 (MainStage 1.0, part of Logic Studio) |
| Latest version | MainStage 3.x (current, sold separately on Mac App Store since Dec 2011) |
LAYOUT conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about LAYOUT files.
