How to open a JSON file online
Three steps, a few seconds, no software.
Open your .DTD file
Drop it on the box, choose it from your device, or paste the data straight in.
View the structure
Your .DTD 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 .DTD file?
The most common data format on the web.
A DTD file is a Document Type Definition, a plain-text schema that specifies the allowed elements, attributes, and nesting rules for XML or SGML documents. Open it in any text editor (Notepad++, VS Code) or a dedicated XML editor like Oxygen XML Editor. DTDs have been largely replaced by XSD for new XML projects, but remain common in DocBook, DITA, and SGML-based publishing systems.
Programs that open .DTD files
| Full name | Document Type Definition |
|---|---|
| Developer | W3C / ISO (SGML origin: ISO 8879:1986; XML DTD defined in W3C XML 1.0 spec, 1998) |
| First released | 1986 (SGML, ISO 8879); 1998 for XML DTD (W3C XML 1.0 Recommendation, February 1998) |
| Category | Text & Code |
| MIME type | application/xml-dtd |
Related viewers
Every viewer is free to use.
Frequently asked questions
Is my .DTD file uploaded anywhere?
No. The file is opened directly from the copy you pick.
My .DTD 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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