Text Diff Checker

See exactly what changed

Compare two blocks of text and highlight exactly what was added and removed, line by line, with options to ignore case and whitespace.

Paste an original version on the left and a changed version on the right, and the diff checker computes a line-by-line comparison using a longest-common-subsequence algorithm. Removed lines are highlighted in red, added lines in green, and unchanged lines stay neutral, so you can spot every edit at a glance without hunting through the text.

Features

Line-by-line difference highlighting
Added vs removed color coding
Ignore case option
Ignore whitespace option
Added / removed counters
Private: nothing leaves your browser

How to use Text Diff Checker

1
Paste the original
Put the first version in the left box.
2
Paste the changed text
Put the second version in the right box.
3
Adjust options
Optionally ignore case or whitespace differences.
4
Read the diff
Green marks additions, red marks removals.

Common use cases

Compare two drafts of a document
Spot changes between contract versions
Review edits to code or config
Check what a collaborator changed

Detailed guide

Compare on your terms

Toggle 'Ignore case' to treat capitalisation differences as identical, and 'Ignore whitespace' so indentation or trailing spaces don't create false differences. Counters tell you how many lines were added and removed. Everything runs locally in your browser, making it safe for comparing sensitive documents, contracts or code.

How the comparison works

The checker uses a longest common subsequence algorithm, the same approach behind version-control diffs, to find the smallest set of insertions and deletions that turns the original text into the changed one. Line mode is best for code, lists and configuration files, where whole lines move or change. Word and character modes are better for prose, where a single edited word would otherwise mark an entire paragraph as changed. Options to ignore case and whitespace help when comparing text copied from different editors that add trailing spaces or change line endings, so you only see changes that matter.

Practical uses

Writers use it to see what an editor changed between drafts, and students to check what a proofreader altered. Developers compare two versions of a config or JSON response to find the one setting that differs. Legal and procurement teams compare contract versions to catch clauses that were quietly reworded. Because both texts are compared in your browser and never uploaded, it's safe for confidential documents. For long documents, compare section by section if the result gets hard to scan, and use the side-by-side view when you need to see both versions in context.

Frequently asked questions

How do I compare two texts?

Paste the original text on the left and the changed text on the right. The tool instantly highlights added lines in green and removed lines in red.

Can it ignore formatting differences?

Yes: enable 'Ignore whitespace' so indentation and trailing spaces don't count as changes, and 'Ignore case' to treat capitalisation as identical.

Does it work for code?

Yes. The line-by-line diff works well for code, config files and any plain text, and it runs locally so private code never leaves your browser.

Is it free?

Yes, completely free with no signup.

How do I compare two texts and see the differences?

Paste the original on the left and the changed version on the right; every insertion, deletion and edit is highlighted line by line, with a similarity percentage.

Is my text uploaded when I compare it?

No. The comparison runs entirely in your browser, so you can safely diff private code, contracts or confidential drafts without anything leaving your device.

Can it compare code and show line-by-line changes?

Yes. It works for plain text, code, logs and Markdown, highlighting added and removed lines so you can review changes like a mini version-control diff.

See exactly what changed

Features

How to use Text Diff Checker

Paste the original

Paste the changed text

Adjust options

Read the diff

Common use cases