Text Diff Checker

"What exactly did they change?" — the question behind every contract revision, edited article, updated policy and reworked email. Reading two versions side by side and spotting differences by eye is slow and unreliable; this tool does it mechanically. Paste the original in the first box and the new version in the second, and you get a line-by-line report: unchanged lines plain, removed lines marked with a minus, added lines marked with a plus — the same convention developers have trusted in code diffs for decades.

Under the hood it computes a longest-common-subsequence alignment, the classic diff algorithm, so it finds the minimal set of changes rather than declaring everything after the first difference "changed". Insert a paragraph in the middle of a document and the diff shows exactly that one insertion, with everything after it still recognised as unchanged.

Typical uses: checking a supplier's "minor updates" to a contract before re-signing, verifying which clauses a landlord edited in a rent agreement, reviewing a colleague's changes to marketing copy, comparing two exports to find the records that differ, or confirming that a template you re-generated matches the old one. Since comparison runs entirely in your browser, it's safe for confidential documents — nothing is transmitted or stored. For prose with heavy rewording inside lines, split it into shorter lines or sentences first for a more granular result.