Diffchecker Desktop includes a local MCP server for your AI assistant. When Claude or Codex asks for a redline or a comparison, Diffchecker runs it on your computer, and your assistant explains what changed.
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Your assistant hands the files to Diffchecker, which compares them on your computer. Every change in the answer comes from that comparison, not from a guess.
What did Northwind change in the supplier agreement? Show me in Diffchecker, and write a change summary for legal.
create_redlinesupplier-agreement-v3.docx → supplier-agreement-v4.docxopen_in_diffcheckerNorthwind made four changes:
Here is the change summary for legal:
Which prices went up between price-list-q3.xlsx and price-list-q4.xlsx? Show me in Diffchecker.
compare_spreadsheetsprice-list-q3.xlsx → price-list-q4.xlsxopen_in_diffcheckerThree prices went up:
Espresso beans went down from $24.00 to $22.80, and two products are new: matcha powder and chai syrup.
Did anything besides the button color change between the checkout screenshots? Show me in Diffchecker.
compare_imagescheckout-before.png → checkout-after.pngopen_in_diffcheckerYes. Besides the Pay button, two things changed:
The highlighted image marks all three:
Ask in your own words. Your assistant picks the Diffchecker tool that fits and gives it the files you name. For contracts and other documents, that is a redline unless you ask for a page-by-page view or formatting changes. For PDFs, it asks which you want.
“Redline the new draft against the signed version.” You get a Word document with tracked changes to accept or reject, a list of every change, and a PDF copy when one can be made.
“What changed between these two config files?” You get every changed line, plus a patch you can apply if you want one.
“What changed in these two PDFs, formatting included?” You get a page-by-page comparison of reworded and moved text, plus font, size, and color changes.
“Are these two screenshots the same?” You get a highlighted image showing every pixel that changed.
“Which cells changed in this export?” You get every added or removed sheet, row, and column, plus changed values and formulas.
“Show me these two drafts in Diffchecker.” You get both files side by side in Diffchecker, so you can check the changes yourself.
“Compare every report in v2 against the matching one in v1.” You get a summary of what changed in each pair.
Point your assistant to two files and ask what changed.
No uploading or copy-pasting. Diffchecker works quietly in the background, so you don't have to open it.
The same accurate comparison as the desktop app, run privately on your computer.
Your assistant explains what changed in plain language, and the full results are saved for you to open anytime.
Choose your assistant. Diffchecker opens and asks you to confirm.
Nothing opened? Update Diffchecker Desktop, or open Preferences, then Integrations, and click Set up next to your assistant.
Paste this into Claude Code or Codex. It opens the same confirmation in Diffchecker, and you approve it with one click.
Set up the Diffchecker Desktop MCP server for this assistant by following the instructions at https://staging.diffchecker.com/mcp/setup.txt
After setup, start a new Claude Code session, reopen Claude Desktop, or restart Codex so it loads Diffchecker.
The MCP server is part of the desktop app. Your assistant starts it, and it stops when your assistant does.
Diffchecker Desktop MCP reads the files from your disk and compares them on your device. They are never uploaded to our servers.
What Diffchecker returns becomes part of your conversation, so the AI provider you chose handles it like anything else you send.
No assistant can use Diffchecker until you set it up. You can manage this in Preferences at any time.
Your assistant tells Diffchecker where each file is on your computer.
Word and PDF files, in any pairing. A redline comes back as a Word file with tracked changes.
Any plain-text file, or text your assistant passes in directly.
Compared pixel by pixel, with optional alignment for photos and scans. Works with the same image formats the desktop app opens.
Workbooks and delimited tables, matched sheet by sheet.
Documents, images, and spreadsheets can be up to 100 MB each, and text up to 10 MB.
Often, yes. Diffchecker reads files from your disk, not from the chat, but an assistant that can run code on the attachment, such as Claude with code execution turned on, can ask Diffchecker to find the identical file on your computer, for example in your Downloads folder. Short plain text can be compared straight from the chat. Otherwise, your assistant asks you where the file is.
Claude on the web and on mobile cannot start a program on your computer, so they cannot use Diffchecker this way.
Diffchecker runs comparisons directly on your device. However, what your assistant reads from the result becomes part of your conversation with your AI provider.
There is an optional setting on macOS that converts PDFs to Word with Microsoft Word, which sends the PDF to Microsoft. It is off by default, and your assistant cannot turn it on.
On your computer, in Diffchecker's mcp-results folder: ~/Library/Application Support/Diffchecker/mcp-results on a Mac, and %APPDATA%\Diffchecker\mcp-results on Windows. If you ask your assistant to save them in another folder, they go there instead. Your assistant's replies link to these files.
Diffchecker deletes the results in its own folder after 30 days. To keep them for a different time, or to delete them all now, open Preferences in Diffchecker, then Integrations, and go to Saved results. Links to deleted results stop working in earlier chats. Uninstalling Diffchecker on Windows, or choosing Diffchecker > Uninstall Diffchecker… on a Mac, deletes them too.
No. Diffchecker Desktop MCP is included with Diffchecker Pro, Legal, and Enterprise, and with the free trial.
Claude Code, Claude Desktop, and Codex can be set up in one click. Other apps that can start a local MCP server can be set up by hand from Preferences.
No. Your assistant chooses pairs of files. Folder comparison is available in the desktop app itself.
Not yet. A PDF needs selectable text and no password.
In Diffchecker, open Preferences, then Integrations, and switch off “Let AI assistants use Diffchecker”.
Deleting the app does not change your assistant's settings, so the entry Diffchecker added at setup stays. On Windows, uninstalling Diffchecker removes these entries. On a Mac, choose Diffchecker > Uninstall Diffchecker…, which removes them and moves the app to the Trash. Before you delete the app any other way, open Preferences in Diffchecker, then Integrations, and click Disconnect all assistants.
If Diffchecker is already deleted, run claude mcp remove diffchecker for Claude Code, or codex mcp remove diffchecker for Codex.
For Claude Desktop, quit it, then delete the diffchecker entry from claude_desktop_config.json. On a Mac, the file is ~/Library/Application Support/Claude/claude_desktop_config.json. On Windows, it is in %LOCALAPPDATA%\Packages\Claude_…\LocalCache\Roaming\Claude if you have that folder, and otherwise in %APPDATA%\Claude.
If you let Diffchecker add a section to Codex's instructions, also delete the section headed "Document comparisons (added by Diffchecker Desktop)" from ~/.codex/AGENTS.md, or from %USERPROFILE%\.codex\AGENTS.md on Windows.
Or reinstall Diffchecker and uninstall it again as described above.
No. Your assistant has to run on the same computer as Diffchecker, in the same desktop session.
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