Diff Checker Online — Free Text & Code Comparison Tool
Compare text, contracts, code files, and documents side-by-side to highlight added, removed, and modified lines.
Runs in your browser. Your files never leave your device. See how to check
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How to do it
- 1Choose your settings
Fill in the details or pick the options you need.
- 2See the result
The preview updates right away as you change things.
- 3Download or save it
Save the result to your device. Nothing is sent to or stored on a server.
About this tool
Spot every single difference between two versions of text or code. Features side-by-side dual panes, unified inline view, whitespace-ignoring options, case-insensitive comparison, and instant addition/deletion counter. 100% private: comparison executes in-browser using fast Myers LCS algorithms.
Tips for best results
Take a moment to read the options before you start, and try the tool with a small sample first. Everything runs in your browser on your own device, so nothing you type or add is uploaded, and closing the tab clears it. If something does not look right, reload the page and try again, or use the report link on this page to tell us what went wrong so we can fix it. If a result still looks wrong, change one value at a time to see which box matters most. Bookmark this page if you will need the tool again.
Quick facts
- Category: Documents
- Works in your browser, no sign-up, no upload.
- Your input stays on your device.
- Available in many languages.
- Content last reviewed:
Frequently asked questions
How does the diff checker identify differences?
It uses the Longest Common Subsequence (LCS) algorithm to track insertions (green) and deletions (red) with line numbers.
Can I ignore spaces and case sensitivity?
Yes, toggle 'Ignore Whitespace' or 'Ignore Case' to focus solely on meaningful content changes.
Can I use it to compare programming code?
Yes, it works flawlessly for Python, JavaScript, HTML, CSS, JSON, SQL, and plain text.
Is there any confidentiality risk with sensitive documents?
Zero risk. Your text is processed entirely inside your local browser tab and never sent to any server.