🔍 Free Text & File Compare — Diff Checker
A real diff, not a toy: the standard LCS (longest common subsequence) algorithm behind every serious diff tool finds the actual line-level changes, and then — the part most free diff checkers skip — a second pass highlights exactly which *words* (or characters) changed within a modified line, not just that the line differs. Beyond viewing the diff, this is a working tool: jump between changes with Prev/Next or a clickable minimap, ignore whitespace/case/blank-line noise, export a real unified-diff (.diff) file, or build a merged result by picking which side to keep for each change. Paste text directly or upload a file on either side (read locally via your browser, never uploaded) and compare code, config files, essay drafts, or any two versions of anything.
Frequently Asked Questions
Is my file actually uploaded anywhere?
No — a chosen file is read directly in your browser (the standard FileReader API) and never leaves your device. The comparison itself also runs entirely client-side.
What does the word-level highlighting show?
When a line was modified rather than fully added or removed, the exact words that changed within that line are highlighted — not just that the whole line differs, which is all most diff tools show.
Is there a size limit?
Each side is capped at 3,000 lines. That covers essays, articles, config files, and most individual source files comfortably; a genuinely huge file (a full codebase, a database dump) needs a dedicated desktop diff tool built for that scale.
Can I compare more than two files at once?
Not yet — this compares one pair at a time. A true simultaneous multi-file (3-way) diff is a meaningfully different, bigger tool, not a small extension of this one.
Can I ignore whitespace, case, or blank-line differences?
Yes — open Compare Options for checkboxes to ignore whitespace, case, and blank lines, plus a toggle between word-level and character-level highlighting. Changing any of them re-compares instantly if a result is already showing.
Can I jump straight between changes instead of scrolling?
Yes — a Prev/Next bar (with N/P keyboard shortcuts) steps through every change in order, and a clickable minimap alongside the diff shows exactly where every change sits in the document, so you can jump straight to one.
Can I export the diff or build a merged result?
Copy Diff and Download .diff produce a real unified-diff file with proper hunk headers, not just a plain-text approximation. Below the diff, a Merged Result panel lets you pick Original, Modified, or Both for each change and copies or downloads the combined text it builds live.