How to open a JSON file online
Three steps, a few seconds, no software.
Open your .DEF file
Drop it on the box, choose it from your device, or paste the data straight in.
View the structure
Your .DEF 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 .DEF file?
The most common data format on the web.
A DEF file is a plain-text linker directive file, most commonly an EXPORTS list that tells the Windows linker which functions a DLL should expose. Open it in any text editor such as VS Code or Notepad++. It is a build input passed to the linker with /DEF:name.def, not a program you run.
Programs that open .DEF files
| Full name | Module-Definition File |
|---|---|
| Developer | Microsoft (Windows toolchain; also used by MinGW/GCC, Watcom, Digital Mars) |
| First released | Windows / OS/2 development, late 1980s–1990s (16-bit, then Win32) |
| Category | Text & Code |
| MIME type | text/plain |
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Every viewer is free to use.
Frequently asked questions
Is my .DEF file uploaded anywhere?
No. The file is opened directly from the copy you pick.
My .DEF 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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