How to open a JSON file online
Three steps, a few seconds, no software.
Open your .MUM file
Drop it on the box, choose it from your device, or paste the data straight in.
View the structure
Your .MUM file opens as a tidy, foldable tree, with the exact line of any error pointed out.
Search, copy or download
Search keys and values, copy any path or value, switch to a table, or download a clean copy.
What is a .MUM file?
The most common data format on the web.
A MUM file is an XML manifest that Windows Update uses internally to track what files, registry keys, and permissions a Windows update installs. You do not need to open or edit MUM files. If Windows shows a CBS MUM Missing error, run DISM /Online /Cleanup-Image /RestoreHealth in an elevated Command Prompt to repair it.
Programs that open .MUM files
| Full name | Windows Update Manifest File |
|---|---|
| Developer | Microsoft Corporation |
| First released | 2006 (Windows Vista, Component Based Servicing architecture) |
| Category | Text & Code |
| MIME type | text/xml |
| Signature | 3C 3F 78 6D 6C |
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Every viewer is free to use.
Frequently asked questions
Is my .MUM file uploaded anywhere?
No. The file is opened directly from the copy you pick.
My .MUM file is invalid. Can you fix it?
We show the exact line and column of the first error. For common problems like comments, trailing commas, single quotes or Python-style True/False/None, click Try to repair and download the fixed file.
How large can the file be?
Up to 50 MB. The tree only builds the branches you open, so even multi-megabyte files stay responsive.
What is JSONPath?
A path like $.orders[3].customer.email that points to one value inside the data. Click any node to see its path and copy it for code, jq or your API docs.
Can I see my data as a table?
Yes. Any array of objects can be shown in the Table view and downloaded as CSV.
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