Comparing two versions of anything by eye is where mistakes hide: the one changed value in a config, the quietly reworded sentence in a contract, the single edited row in an export. Developers solved this decades ago with line diffs; everyone else got told to squint harder.
Our text diff brings the developer tool to a paste box:
- Real diff algorithm — the same longest-common-subsequence matching behind git, so shared lines pair up automatically and only genuine changes are flagged.
- Readable output — removed lines in red with a −, added lines in green with a +, unchanged lines dimmed. Counts update as you type.
- Genuinely private — both texts are processed in your browser tab and deliberately kept out of the URL. Nothing is uploaded, which matters when you’re comparing contracts or unreleased copy.
- Great for code and configs — line-based comparison suits .env files, SQL, YAML, and CSV as much as prose.
Teach a writing or programming course? The diff is embeddable with a single iframe.