Code diff checker: compare code and files online
Compare code or text files online and see exactly what changed. Paste or open the original and modified versions to see added, removed, and changed lines side by side, with files of up to 200,000 lines each kept on your device.
Paste text or drop a code file here. It stays on this device.
Paste text or drop a code file here. It stays on this device.
Files are read in your browser. The comparison is never uploaded.
Changes
Run a comparison to see the changes here.
Compare source code, configuration files, and plain text with aligned line numbers.
Each side can have up to 200,000 lines. Matching and highlighting run locally in this browser.
How to compare code or text files online
- Paste the original text into the left box, or choose Open file to load it.
- Paste or open the modified version on the right.
- Select Compare changes. Added lines are green, removed lines are red, and the changed part of each line is highlighted.
- Use Previous and Next to jump between changes, then copy or download the diff.
A clear view of what changed
This diff checker compares two versions of source code, configuration, or any plain text, line by line. Added and removed lines are aligned, and changed text is highlighted so you can review a code update without reading both files from top to bottom.
- Side-by-side and unified diff views, with line numbers for both files.
- Ignore whitespace to hide indentation and spacing changes.
- Long unchanged sections fold away, and long lines wrap or scroll.
- Compare up to 200,000 lines on each side; no account or upload is needed.
It works with Swift, JavaScript, TypeScript, Python, Go, Rust, Java, Kotlin, PHP, Ruby, C and C++, SQL, HTML, CSS, JSON, YAML, XML, and Markdown, or any other text format.
Frequently asked questions
Is this diff checker free?
Yes. It is free to use, with no account, sign-up, or usage limit beyond the file size it can handle.
Does this tool upload my code?
No. Pasted text and selected files are processed in your browser and are not sent to a server.
What file types can I compare?
Any plain-text file: source code in any language, JSON, YAML, XML, CSV, Markdown, and configuration files. Binary files such as images, PDFs, and Word documents cannot be compared.
What is the difference between side-by-side and unified diffs?
A side-by-side diff shows the original and modified files in two aligned columns. A unified diff shows both in one column, with removed lines marked − and added lines marked +, like git diff.
Can I compare large code files?
Yes. Each side can have up to 200,000 lines, and opened files can be up to 5 MB. The comparison runs in the background so the page stays responsive, and long unchanged sections are folded away so the changes stand out.
What does Ignore whitespace do?
It treats lines with different spacing as equal while matching them, which helps when formatting changes would otherwise obscure code changes.
How is this different from git diff?
It shows the same added and removed lines, but you can paste any two versions without a repository or command line. The unified view uses the same − and + markers as git diff.
Built by Burak Taha Pekşen, who makes iOS apps and writes guides and notes on building them. Publishing on the App Store? Convert App Store Connect reports to CSV, or see all free tools.