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Compare files

Text Compare & JSON Diff

Find every added, removed or changed line

Your files stay on this device. The diff runs in your browser.

+3 added · −2 removed · 4 unchanged

Differences

11 {
2− "holes": 4,
2+ "finish": "zinc",
3+ "holes": 6,
34 "material": "steel",
45 "part": "bracket",
5− "rev": "A"
6+ "rev": "B"
67 }

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Why a line diff for CAD and JSON

Quotes, API dumps and STEP files are large. A single changed hole count or revision letter is easy to miss in a scroll. Compare text files online, line by line: green is added, red is removed. The same view is an online file compare and a way to compare files online or compare two text files, with a copyable unified diff. JSON mode is a JSON diff checker: it pretty-prints and can sort keys so a reshuffled object does not look like a rewrite.

STEP (ISO 10303-21) is text. Two exports of the same part often differ in entity IDs even when the solid is unchanged — that is expected. For geometric size and weight use the STEP model weight calculator. Pretty-print JSON first with the JSON formatter if you only need one document tidied.

Frequently asked questions

Can I compare STEP or CAD text dumps?+

Yes. STEP/STP files are text (ISO-10303-21). Open two revisions as files or paste them. The diff is line-based, so you will see added or removed entities. It does not do a geometric 3D compare.

Is this an online text diff / file comparison tool?+

Yes. Use it as a text diff, text comparison tool, online text diff, online text compare, file comparison tool, or to compare text files / compare two text files. JSON mode is a JSON diff checker and JSON comparison tool. There is also a copyable unified diff — a diff tool online for large pastes.

How does JSON compare work?+

JSON mode parses both sides, optionally sorts keys, pretty-prints, then diffs the lines. That way a reordered object does not look like a huge change. Invalid JSON falls back to a plain text diff.

Are the files uploaded?+

No. Comparison runs in your browser. Large files stay on the device; only the first few thousand lines of the visual diff are drawn, but you can copy the full unified diff.

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