DiffLens — Private Text Compare

Fast, 100% private text diff. Paste or right-click two pieces of text — nothing uploaded, no account, no ads.

DiffLens compares two pieces of text — or two files — and shows you exactly what changed, right in your browser. Nothing is ever uploaded. WHY IT'S DIFFERENT • 100% private — no host permissions, no network requests, no account. The text you compare never leaves your machine (unlike paste-into-a-website diff tools). • Built for prose, not just code — word-wrap on by default and changes highlighted down to the word (or character). • Three views — Unified, Side-by-side (Split), and Inline (the original text with edits marked in place). • Free. No ads, no paywalled features. FEATURES • Word- and character-level highlighting, with smart auto-refine for paths/URLs/IDs. • Move detection — a distinctive line that relocated is flagged as "moved" instead of a separate delete + add. • Jump between differences (↑/↓ or Alt+↑/↓) with a difference counter. • A change-marker rail beside the result — one colored pip per change at its position in the document; click a pip to jump straight there. • Ignore whitespace, blank lines, or case — ignored differences are dimmed (still visible), not silently dropped. • Show whitespace: reveal spaces, tabs and trailing whitespace. • Compare local files — drag a file in or "open file…"; read locally, never uploaded. • Right-click "set as Text A/B" to capture selected text from any page (even across two tabs). • Format JSON — sort keys & pretty-print both sides for a structural compare that ignores key order and formatting noise. • Export the diff — copy as text, copy/download a standard unified diff (.patch, git-apply-ready), or copy as Markdown for GitHub. PRIVACY No accounts, no tracking, no data leaves your device. Settings and text are stored locally only. NOTES • Comparison runs locally; very large, completely-different inputs are compared at a coarser granularity to stay fast. • "Format JSON" uses standard JSON, so integers beyond 2^53 may be reformatted with precision loss (both sides equally). • Chrome (and Chromium-based browsers).