What is an online difference checker?

An online difference checker is a browser-based tool that compares two pieces of content — text, code, files, or data — and visually highlights what changed between them. Additions are shown in green and deletions in red, so you can instantly spot every insertion, removal, or modification without installing any software.

How does an online difference checker work?

It applies a diff algorithm (such as Myers diff) to the two inputs you provide. The algorithm finds the shortest sequence of additions and deletions that transforms one version into the other, then displays the result as a color-coded, side-by-side comparison. For files like PDFs or images, the tool first extracts the relevant content (text or pixels) before running the diff.

Is FreeDiffChecker free to use?

Yes — every comparison tool on FreeDiffChecker (text, code, JSON, XML, image, document, Excel, and folder) is completely free. No credit card or account is needed to compare. Creating a free account unlocks extra features like saving diffs to your dashboard and generating persistent shareable links.

Can I compare two files without installing software?

Absolutely. FreeDiffChecker is fully browser-based, so there is nothing to download or install. It works on any modern browser — Chrome, Firefox, Safari, or Edge — on desktop, tablet, or mobile. Simply open the site, choose your comparison type, and start comparing.

How do I compare two files online?

Choose the correct tool for your file type: use Text / Code for plain text and source files, Documents for PDFs and Word files, Excel & CSV for spreadsheets, Images for PNG/JPG files, or Folders for ZIP archives. Then upload or paste both files into the two panels and click Compare — results appear instantly with differences highlighted.

How do I compare two text files or documents online?

Open the Text / Code checker on FreeDiffChecker, paste the contents of each file into the left and right panels, and click Compare. For Word (.docx) or PDF documents, use the Documents tool instead — it extracts the text content automatically and highlights every paragraph- and line-level change.

How do I compare two code files online?

Navigate to the Text / Code diff page, paste or type each code file into the corresponding panel, and select your language from the dropdown for syntax highlighting. The code difference checker supports over 50 languages including JavaScript, Python, Java, Go, Ruby, and C++ — powered by Monaco Editor, the same engine used in VS Code.

How do I compare two PDF files online?

Go to the Documents tool on FreeDiffChecker and upload your two PDF files. The tool extracts the text layer from each PDF and presents a line-by-line diff, highlighting all additions and deletions. This is ideal for spotting edits in contracts, legal briefs, research papers, or any version-tracked document.

How do I compare two Word documents online?

Use the Documents comparison tool and upload your .docx or .doc files. FreeDiffChecker extracts the full text content and shows a side-by-side diff so you can see every sentence that was added, removed, or changed — no Microsoft Word installation required.

How do I compare two folders online?

Zip each folder into a .zip archive, then open the Folder diff tool on FreeDiffChecker and upload both archives. The tool reconstructs the directory tree and lists every file that was added, removed, or modified — including the line-level changes inside each modified file.

What file types does the difference checker support?

FreeDiffChecker supports a wide range of formats: plain text, source code (50+ languages), JSON, YAML, XML, Markdown — Documents: PDF, DOCX, DOC — Spreadsheets: XLSX, XLS, CSV — Images: PNG, JPG, WEBP, GIF — Folders: ZIP archives up to 10 MB per file.

Can I use the code difference checker for multiple languages?

Yes. The Text / Code diff page automatically detects the language from the file extension or content, and applies syntax highlighting for over 50 languages including JavaScript, TypeScript, Python, Java, C#, C++, Go, Rust, PHP, Ruby, Swift, Kotlin, SQL, and more.

How do I compare JSON or XML files online?

Open the Text / Code checker, paste your JSON or XML into both panels, and select the matching language. The JSON difference checker and XML difference checker highlight structural changes — added or removed keys, modified values, and reordered nodes — making it easy to debug API responses, configuration files, and data exports.

Can I compare large files, and what is the file size limit?

The maximum upload size per file is 10 MB. Most text, code, document, and spreadsheet files fall well within this limit. For large codebases or directory trees, zip only the relevant folders to reduce the archive size. Very large binary files (such as high-resolution images) may need to be resized first.

Is an online difference checker safe to use? Is my data private?

Yes. All data is transmitted over HTTPS. When you run a comparison, your files and text are sent to our server only for processing and are never stored unless you explicitly click Save or Share. When you save or share a diff, the result is stored in our database and remains accessible until you delete it or it reaches the expiry date you chose. For complete details, see our Privacy Policy.

How do I delete my account?

Go to My Profile (click your name in the top-right menu) and scroll to the Danger Zone section. Click "Delete Account" and type DELETE to confirm. This permanently removes your account and all saved diffs and cannot be undone.

What happens to my saved diffs if I delete my account?

All saved and shared diffs associated with your account are permanently and irreversibly deleted from our servers. Any shareable links you previously generated will immediately stop working.

Do I need an account to compare files?

No account is required to use any comparison tool. Sign up for a free account only if you want to save diffs to your personal dashboard or create persistent shareable links that others can view later.

How do shareable links work?

After running a comparison, click the Share button to generate a unique, read-only link. Anyone with the link can view the result without an account. Signed-in users can set the link to expire in 1 day, 7 days, 30 days, or never — links set to never expire remain accessible until you manually delete them from your dashboard.

All comparison tools in one place — 100% free

Free Difference Checker Online

Compare text, code, images, documents, and spreadsheets side-by-side — in your browser, instantly, and always free. No software to install, no account required.

Start Comparing Now

All-in-One Difference Checker Tools

Text & Code

Compare plain text, source code, JSON, YAML, XML, and strings with syntax highlighting across 50+ languages.

Compare Text & Code

Images

Find pixel-level differences between two images with an interactive slider and overlay view.

Compare Images

Documents

Compare PDF and Word documents (.pdf, .docx, .doc) by text content — ideal for contracts, reports, and essays.

Compare Documents

Excel & CSV

Highlight changed, added, and removed cells across sheets in spreadsheet files and CSVs.

Compare Spreadsheets

Folders

Upload two zipped folders to see added, removed, and modified files in a clear tree structure.

Compare Folders

What Is a Difference Checker?

A difference checker (or "diff tool") compares two pieces of text, code, or data and highlights exactly what changed — additions in green, deletions in red, and modifications clearly marked. FreeDiffChecker is a free online difference checker that brings this power to your browser, supporting every format you use daily.

Instant Results

Paste text or upload a file and see differences highlighted in real time. No page reloads, no waiting — just instant, accurate comparisons powered by proven diff algorithms.

Works Everywhere

Fully browser-based and mobile-friendly. Our online difference checker works on any device — desktop, tablet, or phone — without installing any software or extensions.

Privacy First

Uploaded files are processed securely and never stored permanently. Your content stays yours — saved diffs are kept only as long as you choose, and you can delete them at any time.

Built for Everyone

Whether you're a developer running a code difference checker, a student proofreading paragraphs, or an analyst comparing spreadsheets — FreeDiffChecker is designed for all skill levels.

Compare Any Format You Work With

Our free difference checker online supports a wide range of formats so you never need to switch tools.

How to Use the Difference Checker

Get started in seconds — no account or installation needed.

Choose a Comparison Type
Select from text, code, image, document, Excel, or folder diff using the tool cards above.
Paste or Upload Your Content
Drop files onto the page or paste text directly into the editor panels — no formatting required.
See Differences Instantly
Changes are highlighted in real time with green for additions and red for deletions.

Try It Free Now

Frequently Asked Questions

Common questions about our free online difference checker.

Guides & Tutorials

Not sure which tool to use, or want to understand how diff algorithms work? Our guides cover everything from comparing PDFs and Excel files to the difference between git diff and an online diff tool.

How to Compare Two PDF Files Online git diff vs. an Online Diff Tool Diff Algorithms: Myers, Patience & Histogram Compare Excel Files: VLOOKUP vs. Diff Tool

View all guides

Free Difference Checker Online

All-in-One Difference Checker Tools

Text & Code

Images

Documents

Excel & CSV

Folders

What Is a Difference Checker?

Instant Results

Works Everywhere

Privacy First

Built for Everyone

Compare Any Format You Work With

Text & Paragraph Difference Checker

Code Difference Checker Online

JSON & XML Difference Checker

Document & PDF Difference Checker

Excel & CSV Difference Checker

Image Difference Checker

How to Use the Difference Checker

Choose a Comparison Type

Paste or Upload Your Content

See Differences Instantly

Frequently Asked Questions

Guides & Tutorials