What a diff checker does
A diff checker compares two versions of a text and shows exactly what changed. Added lines, removed lines and unchanged lines are colour-coded, so you can review an edit in seconds instead of reading both versions end to end. Developers use it for config files, code snippets and API responses. Writers use it to compare drafts and contracts.
This tool uses a longest-common-subsequence (LCS) algorithm to find the smallest set of line changes between the two texts. It runs in your browser, so confidential documents are not uploaded.
How to use it
- Paste the original text on the left and the changed text on the right.
- Run the comparison to see added lines, removed lines and unchanged lines highlighted.
- Turn on Ignore whitespace or Ignore case to hide changes that do not matter.
- Use the counters to see how many lines were added, removed or changed.
Example
Two small versions of a config:
Original Changed
name=web name=web
port=80 port=8080
debug=true (removed)
timeout=30
Result: port line changed, debug removed, timeout added.Tips
- Format both sides the same way first. For JSON or SQL, run them through the formatter so line breaks match, otherwise the whole file looks changed.
- Use Ignore whitespace when comparing text from different editors or operating systems.
- Compare large files in parts if the page feels slow.
Everyday uses of a diff
People compare text for many reasons:
- Checking what changed between two versions of a config file before a deployment.
- Reviewing edits in a contract, policy or article draft.
- Comparing two API responses to find the field that changed.
- Spotting whether two lists, logs or exports are really the same.
Related tools
- JSON Formatter & Validator: Format, validate, and beautify JSON with clear error messages for developers.
- Code Minifier: Minify JavaScript, CSS, HTML, or JSON by stripping comments and unnecessary whitespace.
- Universal Config Converter: Convert between .properties, JSON, and YAML formats instantly. 100% client-side.
- Remove Duplicate Lines & Sort Lines: Remove repeated lines, keep the first of each, and sort or reverse the list. Nothing leaves your browser.