How to open a JSON file online
Three steps, a few seconds, no software.
Open your .ATT file
Drop it on the box, choose it from your device, or paste the data straight in.
View the structure
Your .ATT 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 .ATT file?
The most common data format on the web.
An ATT file (most often named postdata.att) is plain text containing the field=value pairs a browser submitted through an HTML form. Open it in any text editor - Notepad, Notepad++, or TextEdit - no special software needed. If the file arrived as an unexpected email attachment, verify it is really text before trusting it.
Programs that open .ATT files
| Full name | Web Form Data File (postdata.att) |
|---|---|
| Developer | N/A (produced by web browsers/servers on form submission; no single vendor) |
| Category | Text & Code |
| MIME type | text/plain |
Related viewers
Every viewer is free to use.
Frequently asked questions
Is my .ATT file uploaded anywhere?
No. The file is opened directly from the copy you pick.
My .ATT 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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