Free Online Diff Checker — Compare Text Side by Side
Paste two blocks of text, code, JSON, or any plain text content to instantly see what changed between them. Additions and deletions are highlighted line by line — entirely in your browser, no uploads required.
✓ Free developer tool✓ No account required✓ Browser-based utility✓ Fast results✓ Mobile friendly
Original Text
Changed Text
This tool runs in your browser and does not upload your data to BuBird servers.
How To Use
How to Use Diff Checker
1
Paste the Original Text
Enter or paste the original version of your text, code, or JSON into the left panel.
2
Paste the Modified Text
Enter the updated version into the right panel.
3
Compare
Click the Compare button (or see results live). Added lines are highlighted in green; removed lines in red.
4
Review the Differences
Scroll through the diff to review all changes between the two versions and identify what was added, changed, or deleted.
Example
Example Use
Reviewing a Configuration File Change
Before deploying a new version of an application, you want to confirm only the intended settings changed in the config file. Paste the previous config into the left panel and the new config into the right panel. The diff highlights exactly which lines were added, removed, or modified — making it easy to catch unintended changes before they reach production.
Use Cases
Who Uses Diff Checker
Developers
Compare code snippets, function implementations, or config files to review changes before committing.
QA Engineers
Compare expected vs actual API response bodies to identify unexpected field changes during testing.
Technical Writers
Compare document drafts to track editorial changes between revisions of technical documentation.
API Integrators
Compare two API response payloads to identify schema changes between API versions.
DevOps Engineers
Diff environment variable files or infrastructure configuration changes before deployment.
Students & Learners
Compare submitted code with a reference solution to understand exactly what differs.
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FAQ
Frequently Asked Questions
What types of content can I compare with the diff checker?
You can compare any plain text including code, JSON, configuration files, SQL queries, HTML, markdown, and prose. The tool works with any text-based content.
Does the diff checker upload my text to a server?
No. The comparison runs entirely in your browser. Your text is never sent to BuBird servers.
How are differences highlighted?
Additions are highlighted in green and deletions in red. The diff is shown line by line so you can quickly spot what changed between the two versions.
Can I use this to compare JSON files?
Yes. Paste two JSON blobs to see exactly which keys or values differ. For best results, format both JSON inputs first using the JSON Formatter so the structure is aligned before comparing.
Is there a limit on the amount of text I can compare?
There is no fixed limit. The tool processes text in your browser, so very large inputs may be slower depending on your device's available memory and CPU.