KordFree diff tool
Compare two PDF files
Diff two PDF revisions in your browser, free, no account: page-by-page comparison with the changes visible, zoom on both sides, and alignment correction for sheets that shifted between revisions. Built by Kord; opens with a sample P&ID pair loaded.
Free, no account. Opens with a two-revision P&ID loaded.
A revised drawing comes back as pid-rev-3.pdf, and the transmittal describes the change about as precisely as transmittals ever do. The established options are Acrobat's Compare Files (paid), Bluebeam's overlay (paid, and fair value if you live in it all day), or printing both revisions and holding them up to the window.
This one is free and runs in the browser. Drop the two revisions, page through them side by side with the changes visible, and zoom in on the region nobody clouded. When the whole sheet shifted between revisions - a reframed title block is enough - the alignment can be corrected so the diff shows the real changes instead of one page-sized one.
What the comparison shows
What you get on screen once both files are in, and why each piece is there:
- Page by page, side by side. Both revisions travel together as you page and zoom, so your eyes stay on the same region of both.
- Changes you can point at. The moved dimension, the rerouted line, the edited note - visible in the comparison, not inferred from a rev triangle that may or may not have been placed.
- Alignment correction. A sheet that shifted or was reframed between revisions can be realigned, which is the difference between a readable diff and a page of noise.
- Drawings and text documents both. A P&ID and a 40-page spec are both PDFs; both compare here.
How to compare two PDF files
Three steps, none of which is signing up:
- Open the diff tool - it loads with a two-revision P&ID already compared, so you see the result shape before committing your own files.
- Drop your two PDF files into the Before and After slots - up to 25 MB each.
- Read the comparison. If someone else needs to see it, Share turns it into a link.
Every way to compare PDF files
Where this sits among the usual answers, honestly:
| Tool | Reach for it when | Worth knowing |
|---|---|---|
| Adobe Acrobat's Compare Files | You have Acrobat Pro and the document is text-first | Paid, and drawing comparisons read worse than text ones |
| Bluebeam Revu overlay and compare | You are in construction, you already own Revu, and markup is the point | Paid per seat; the comparison lives inside Revu |
| Draftable, Diffchecker | A quick online diff of an office document | Generic document tools - fine for specs, not built for drawings |
| This one (Kord's diff tool) | Drawing revisions, P&IDs, and specs, free, with alignment correction when the sheet moved | In the browser, 25 MB per file |
FAQ
The questions people ask before dropping real files on a free tool, answered plainly:
Is it free?
Yes. No account, no trial clock, no watermark. The tool exists because we build Kord, version control for engineering document sets, and a diff you can run in ten seconds explains the product faster than any brochure.
Do my drawings get stored?
Files are kept only as long as it takes to draw the comparison. Most formats render in your browser; Word and PowerPoint are converted to a preview by our servers in memory, and a file too big to ride a request travels through a short-lived upload that is deleted automatically. There is no account, so there is no history to attach anything to. The longer answer is at work.withkord.com/security.
Does it work on P&IDs and engineering drawings?
That is what it is for - the sample pair it opens with is a feed-section P&ID at two revisions. Dense linework is exactly where eyeballing two prints fails and a rendered comparison earns its keep.
What is the size limit?
25 MB per file. Larger Office files are routed through a short-lived upload behind the scenes, so a 20 MB workbook behaves the same as a 2 MB one.
Can I send someone the comparison?
Yes. The Share button mints a link that renders the same comparison for whoever opens it - no account on their end either. It beats mailing two attachments and a paragraph of directions.
How is this different from Bluebeam?
Bluebeam is a markup tool with a compare feature; this is a comparison, free, in the browser. If your team lives in Revu for markup, keep Revu. If the question is only "what changed between Rev 2 and Rev 3", you should not need a seat of anything to answer it. And when the real problem is the whole submittal package rather than one sheet, that is Kord itself - version control and review sessions across the document set.
When two files aren't the real problem
A one-off diff answers a one-off question. If your team compares PDF files every revision cycle - and the revision that matters sits next to drawings, specs, and calc sheets that have to agree with it - that is the job Kord exists for: version control on the whole document set, this same visual comparison between any two revisions, and review sessions with sign-off before anything is issued. The longer argument is in Git for documents.
Compare other formats
The same tool reads eleven formats - the full list is on the compare index. Nearby: Compare two Word documents · Compare two Visio files · Compare two DXF files.