What is a .sketch file?
Sketch Design Document · Design · Sketch B.V. · 2010
A .sketch file is a design document from Sketch, the macOS interface-design tool. Modern Sketch files are ZIP packages of JSON describing the artboards, layers and styles of a UI design.
What is a .sketch file used for?
Since a .sketch is a ZIP of JSON, it starts with the ZIP signature and can be unzipped to inspect its structure. Sketch is Mac-only, which is the usual sticking point for people on other systems.
To view a Sketch file without the app, use the free Sketch web viewer, or open it in tools like Figma (import) or Lunacy on Windows, which read the format.
What opens a .sketch file?
The .sketch format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- Lunacy
- Figma (import)
- 7-Zip (to inspect)
macOS
- Sketch
- Lunacy
- Figma (import)
Linux
- Lunacy
- Figma (web)
Web
- Sketch web viewer
- Figma
Open a .sketch file step by step
- Confirm the file really is a .sketch. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with Lunacy or Figma (import).
- On Mac, use Sketch or Lunacy.
- On Linux, try Lunacy or Figma (web).
- Still stuck? Convert the .sketch to fig, which opens more widely.
Why can't I open my .sketch file?
Almost always because no installed app understands Sketch. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .sketch at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .sketch file
You can convert a .sketch file to fig, pdf, png, svg using a conversion tool or the export menu of an app that opens it.
What is the .sketch file signature (magic bytes)?
A .sketch file starts with the hex bytes 50 4B 03 04, which read as PK.. in ASCII. Programs identify Sketch by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for Sketch. For a full breakdown, see the ZIP file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 50 4B 03 04 | 0 | PK.. | ZIP package (PK..) |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .sketch file?
A .sketch file is a design document from Sketch, the macOS interface-design tool. Modern Sketch files are ZIP packages of JSON describing the artboards, layers and styles of a UI design.
How do I open a .sketch file on Windows?
Use Lunacy, a free Windows app that opens Sketch files, or import it into Figma. To just peek inside, rename it to .zip.
Is a .sketch file a ZIP?
Modern Sketch files are, yes: a ZIP of JSON and images. That is why they start with the ZIP signature and can be unzipped.
Can Figma open Sketch files?
Yes. Figma can import .sketch files, converting the artboards and layers, which is a common way to open them off a Mac.
Related formats
Sources
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