# Diff Checker: Compare Text and Files Side by Side > Compare two texts, files, PDFs or Word documents and see every change by line, word or character. Free, no sign-up, and nothing leaves your browser. https://www.kortex-notebooklm.com/tools/diff-checker [Free tools](/tools) # Compare two texts or files side by side Paste or drop two versions of anything, from a contract to a config file. See every added, removed and changed line, down to the word or character. - Free, no sign-up - Runs in your browser. Your files never leave your device. - Updated November 10, 2026 **To compare two texts, paste the original on the left and the changed version on the right. The diff checker marks every added, removed and changed line, and the words or characters that changed inside them.** It runs entirely in your browser, reads PDF and Word files as well as plain text and code, and exports a .patch file, an HTML report or a PDF. ## How do I compare two files? 1. Click **Open two files** and pick both at once, or drop a file on each side. You can also paste text, or a copied file, straight into either side. 2. The comparison updates as you type. Red marks what left the original; green marks what arrived in the changed version. 3. Step through the changes with the arrow buttons, or press Alt + ↓ and Alt + ↑ (F7 works too). The counter shows where you are, such as “3 of 12”. 4. Use **Export** to download a .patch, an HTML report, or to print or save the comparison as a PDF. ## Which view should I use? **Side by side** keeps both versions editable and lines up the unchanged parts. It is easiest for reviewing a document, or for fixing one side while you look at the other. **Unified** shows one column with removed lines above the lines that replaced them, the way code review tools and patch files do. It also fits a phone screen. Turn on **Fold unchanged lines** to hide long stretches that did not change. ## Can I compare PDF or Word documents? Yes. The tool pulls out the text of each PDF page, Word document or EPUB chapter on your device. Then it compares paragraph by paragraph. This finds changed wording between two drafts of a contract, a paper or a policy. It ignores layout, fonts and images. A scanned PDF has no text to compare. Use [Image to Text](/tools/image-to-text) to read it first. ## What do the ignore options change? | Option | Counts as the same | | --- | --- | | Whitespace | `if (x) {` and `if(x){`; a re-indented paragraph | | Upper and lower case | “Atlantic Coast” and “Atlantic coast” | | Blank lines | A version with an extra empty line between paragraphs | `` Line endings never count. A file saved on Windows and the same file saved on a Mac compare as identical, and the status line tells you that they differ. ## How do I share a comparison? Download the HTML report, a single page anyone can open. Or download the .patch file for anyone who works with Git. For short texts, **Copy a link with both texts** packs them into the link itself, compressed, after the `#`. Browsers never send that part of a link to a server, so the texts do not pass through ours. But anyone you give the link to can read them. ## How is this different from other free diff tools? Many free diff checkers limit their best features. When we checked on 4 November 2026, Diffchecker’s free plan allowed 10 character-level comparisons and 5 PDF exports a month ([Diffchecker pricing](https://www.diffchecker.com/pricing/)), and text-compare.com compared texts on its server and kept ignore-case, ignore-whitespace and statistics for paid users ([text-compare.com](https://text-compare.com/)). Here every option is free with no monthly count, and the comparison never leaves your device. ## Keyboard shortcuts
Next or previous changeAlt + ↓ / ↑, or F7 / Shift + F7
Swap the sidesAlt + S
Side by side or unifiedAlt + U
Lines, words or charactersAlt + G
Ignore whitespace or caseAlt + W, Alt + C
Open two files, download a patchCtrl/⌘ + O, Ctrl/⌘ + S
Find in a sideCtrl/⌘ + F
All shortcuts?
**Save what you find in one click.** Kortex is a Chrome extension for Gemini Notebook (formerly NotebookLM). It sends AI chats, web pages, posts and YouTube videos into the notebook you pick. It keeps your notebooks organized. It exports them back out. [Add to Chrome](https://chromewebstore.google.com/detail/kortex/hdapplggdhndkblofffknpmnnnnbncbn) `` ## Questions Is my text uploaded anywhere? No. Code in your browser tab compares both texts, and your device reads the files. The page sends no copy of your text anywhere. You can check this in your browser’s network panel. The optional share link puts both texts inside the link itself, after the #. Browsers never send that part to a server, but anyone you give the link to can read the texts. Can I compare two PDF or Word files? Yes. Open or drop a PDF, a Word (.docx) or an EPUB file on either side. The tool pulls the text out on your device and compares it like any other text. Scanned PDFs have no text layer, so run them through Image to Text (OCR) first. For a PDF with a password, save a copy without it. What is the difference between lines, words and characters? All three mark the changed lines in red on the left and green on the right. Words also highlights the words that changed inside those lines. Characters highlights single letters, which is best for typos, numbers and code. The tool never highlights unchanged text. What does ignoring whitespace, case or blank lines do? Ignoring whitespace compares lines with every space and tab removed, so re-indented or re-spaced lines stop counting as changes. Ignoring case treats “Coast” and “coast” as the same. Ignoring blank lines means added or removed empty lines never count. Windows and Unix line endings never count as changes. How big can the texts be? Each side takes a text file of up to 50 MB, or a PDF or Word file of up to 300 MB. Big comparisons run in a background thread, so the page stays responsive. Two 10,000-line files compare in well under a second on a laptop. How do I apply the .patch file? In the folder that holds the original file, run git apply changes.patch, or patch -p1 < changes.patch. The patch always contains every change, even ones you chose to ignore on screen. So it applies cleanly and turns the original into the changed version. Is there a limit on comparisons, or an account? No. There is no account, no daily or monthly limit, no file-size paywall and no ads. Character-level highlighting, PDF files, the HTML report and printing are all free. Does it remember my text? This device remembers your settings (view, highlighting and the ignore options). It keeps your text only if you tick “Keep my last input on this device”. Unticking it deletes what was kept. ## More free tools - [**JSON Formatter** Format, check, browse and convert JSON, even very large files.](/tools/json-formatter) - [**CSV Converter** Convert CSV to and from JSON, Excel, Markdown and more.](/tools/csv-converter) - [**Merge PDF** Join PDFs into one file. Reorder and rotate pages in your browser.](/tools/merge-pdf) - [**Split PDF** Split a PDF by page, range or size. Or pull out the pages you need.](/tools/split-pdf) - [**PDF to Text** Get clean text or Markdown out of any PDF, page by page.](/tools/pdf-to-text) ## Save what you find in one click. Kortex is a Chrome extension for Gemini Notebook (formerly NotebookLM). It sends AI chats, web pages, posts and YouTube videos into the notebook you pick. It keeps your notebooks organized. It exports them back out. [Add to Chrome](https://chromewebstore.google.com/detail/kortex/hdapplggdhndkblofffknpmnnnnbncbn) No card needed.