FileopiaText Diff Checker
Compare two versions of text side by side and see added, removed and changed lines with word-level highlighting. Free diff checker that runs in your browser – nothing is uploaded.
- Upload
- Options
- Download
- ✓ 100% free
- ✓ No sign-up
- ✓ No limits
- 🔒 Files never leave your device
How to: Text Diff Checker
- Paste the original text on the left.
- Paste the changed text on the right.
- Review highlighted differences and download a diff file.
Spotting what changed between two versions of a document by eye is slow and error-prone. Paste both versions here and the diff checker shows removed lines in red, added lines in green and changed lines in yellow with the exact words highlighted. It is useful for contracts, essays, translations, code and any text that has been edited by someone else.
Common uses
- See what a colleague or client changed in a contract, policy or proposal.
- Compare two drafts of an essay, article or translation.
- Check configuration files, code snippets or SQL before deploying.
- Compare lists of names, emails or product codes exported at different times.
Tips for best results
- Turn off “Show unchanged lines” to see only the differences in long texts.
- For PDFs, extract the text first with PDF to Text or use Compare PDF for a visual report.
- Sort both lists first with Remove Duplicate Lines if the order does not matter.
- Download the diff to keep a record of what changed and when.
How the comparison works
The tool uses a longest-common-subsequence algorithm, the same family of methods behind Git and the Unix diff command. It first finds the lines the two texts share, then marks everything else as added or removed. When a removed line is directly followed by an added one, it treats them as a changed line and runs a second, word-level comparison so you can see the exact edit – a changed date, a new clause, or a corrected spelling.
Privacy for sensitive comparisons
Many online diff tools send both texts to a server. Here the comparison runs entirely in your browser, which matters for legal drafts, HR documents, unreleased code and personal data covered by regulations such as GDPR. You can even disconnect from the internet after the page loads and the tool will keep working.
Why use Fileopia for Text Diff Checker?
| Fileopia | Typical upload-based sites | |
|---|---|---|
| What you type is sent to a server | No – stays in your browser | Often |
| Sign-up required | Never | Often for bigger jobs |
| Hourly / daily task limits | None | Common on free plans |
| Works offline after loading | Yes, for most tools | No |
Private by design
Everything you type is calculated by JavaScript in this tab. Nothing is sent to Fileopia or anyone else, and there are no accounts or tracking cookies tied to what you enter.
- Test it yourself: once this page has loaded, switch off Wi‑Fi or mobile data and run the tool – it keeps working.
- Check the network: open your browser’s developer tools (F12 → Network) while processing; you will see no file upload requests.
- Nothing to delete: close the tab and the data is gone – there is no server copy, no retention period and no account.
Frequently asked questions
Can I compare code
Yes. The checker works line by line like developer diff tools and keeps indentation, so it is suitable for source code, configuration files, CSV data and logs.
How do I ignore formatting changes
Tick “Ignore whitespace differences” to treat extra spaces and tabs as equal, and “Ignore upper/lower case” to ignore capitalisation changes.
Is Text Diff Checker really free?
Yes. Every tool on Fileopia is 100% free with no file limits, no sign-up and no watermarks. The site is supported by unobtrusive ads.
Are my files uploaded to a server?
No. Fileopia processes your files directly in your browser using JavaScript. Your documents never leave your device, so they stay completely private.
Does it work on mobile?
Yes. Fileopia works in any modern browser on Android, iPhone, iPad, Windows, Mac and Linux.