Text Diff Checker
Compare two texts and see the differences highlighted. Line-by-line comparison.
Compare two pieces of text side by side and see exactly what has changed. Additions, deletions, and unchanged lines are clearly highlighted.
A diff checker compares two pieces of text and highlights every addition, deletion, and unchanged line between them. It's the same algorithm git diff uses, surfaced without the command line. Paste an old version on the left, a new version on the right, and the tool aligns matching lines, flags inserts in green, deletes in red, and leaves the rest alone.
The practical value shows up when you're comparing things that aren't in version control: two JSON API responses that should be identical but aren't, a vendor's configuration before and after their "no changes" email, log output between two test runs, or a draft of a contract against the counter-signed PDF. A proper line-by-line diff tells you in seconds whether anything actually changed and exactly what moved.
The comparison runs locally using a longest-common-subsequence algorithm, which is the same approach as diff(1), git, and Myers' paper. Whitespace-only changes are called out separately from substantive edits so you can ignore formatting noise when you need to.
- 1
Paste both texts
Drop the original on the left and the revised version on the right. Any text works — code, config, prose, logs, JSON.
- 2
Review highlighted differences
Added lines are highlighted green, removed lines red, and unchanged lines are shown for context. Each changed region is grouped so you can scan top to bottom.
- 3
Toggle options as needed
Switch between side-by-side and inline views, or ignore whitespace-only changes when you only care about substantive edits.
Comparing config files
Spot exactly which lines changed between two .env files, two kubernetes manifests, or two versions of a CI workflow.
Reviewing contract edits
Paste the original and the redlined version to see every clause a counterparty altered before signing.
API response regressions
Compare an API response from today against one from last week to find fields that appeared, disappeared, or changed shape.
Log-output comparison
Diff two test-run logs to isolate the exact line where behavior started to diverge.
What algorithm does the diff use?
It uses the longest-common-subsequence approach — the same family as Myers' diff algorithm used by git and GNU diff — which produces the minimal edit script between the two inputs.
Can I ignore whitespace differences?
Yes. Toggle the ignore-whitespace option to collapse formatting-only changes so you see only meaningful edits. Useful when comparing auto-formatted code.
Is there a size limit?
Pasting up to a few megabytes works well. For very large files, split them into sections — diffing ten megabytes of text in the browser gets slow regardless of the tool.
Does it support word-level or character-level diffing?
The default view is line-based. Within each changed line, inline highlights show the specific tokens that differ so you can spot a single typo inside a long sentence.
Is my text uploaded anywhere?
No. The comparison runs entirely in your browser — nothing is sent to a server, logged, or stored.