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WK4 file: what it is and how to open it

Lotus 1-2-3 spreadsheet. Here is what a .wk4 file contains, how to open one on any device, and a viewer that opens it right in your browser.

Open a .wk4 file hereChoose fileRead in your browser. Nothing is uploaded.

What the viewer shows

  • Whether the file matches the .wk4 signature
  • The first bytes as hex
  • A preview when your browser can display it

What is a .wk4 file?

A .wk4 file is a lotus 1-2-3 spreadsheet. Its registered MIME type is application/vnd.lotus-1-2-3, which places it in the application or document family of formats.

WK4 is a binary format: the contents are not readable text, so opening it in a text editor shows scrambled characters.

Files of this type usually begin with the bytes 00 00 02 00 06 04 06 00 08 00 00 00 00 00. That signature is how programs recognise the format even when the extension is wrong or missing.

The same format is also saved with the extensions .123, .wk1, .wk3, .wks.

WK4 file format details

Extension.wk4
FormatLotus 1-2-3 spreadsheet
MIME typeapplication/vnd.lotus-1-2-3, application/x-lotus123, application/x-123
CategoryApplication or document
Text or binaryBinary
File signature00 00 02 00 06 04 06 00 08 00 00 00 00 00
Registered with IANAYes
Other extensions.123, .wk1, .wk3, .wks

How to open WK4 files

WindowsWK4 files (Lotus 1-2-3 spreadsheet) are made by specific software. The reliable way to open one is with the program that created it; a generic viewer will only show raw data.
MacThe same applies on a Mac: look for a Mac version of the program that makes WK4 files.
iPhone and iPadPhones rarely open this type of file directly. The viewer above can show what is inside it without installing anything.
AndroidThe same applies on Android. The viewer above shows the first bytes of the file so you can confirm what it is.

Can you convert a .wk4 file?

TapToConvert does not convert WK4 files. The usual route is to open the file in the program that made it and use its Export or Save as option.

WK4 file FAQ

What is a .wk4 file?

A .wk4 file is a lotus 1-2-3 spreadsheet, with the MIME type application/vnd.lotus-1-2-3.

How do I open a .wk4 file?

With the program that created it. The viewer on this page shows what is inside without installing anything.

Is a .wk4 file safe to open?

WK4 files hold data rather than programs, but any file from an unknown source can be crafted to exploit the software that opens it. Keep that software up to date. The viewer on this page only reads the bytes and never runs anything.

What is the MIME type of .wk4?

application/vnd.lotus-1-2-3, and it is also seen as application/x-lotus123 or application/x-123. Web servers send this type so browsers know how to handle the file.

Is WK4 a text or binary format?

Binary. Its contents are not readable as text.

File type facts come from the IANA media type registry, the mime-db project and the freedesktop.org shared MIME database.

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