Text Compare

Paste two versions and see exactly what changed — line by line and word by word, entirely in your browser.

FreeNo SignupBrowser-Based

Your text never leaves your browser. The comparison runs on your device, so confidential documents and code stay private.

How it works

Paste the original text on the left

Paste the changed text on the right

Read the highlighted differences

About this tool

A diff checker answers one question quickly: what actually changed between these two versions? That comes up constantly — proofreading an edited draft against the original, checking which clause moved in a contract, working out what a colleague altered in a config file, or confirming that a copy-paste really was identical. Reading both versions side by side and trusting your eyes is slow and unreliable; this does it in one pass.

The comparison works at two levels. First it matches up lines that are unchanged, so you can see the shape of the edit. Then, for lines that were modified rather than added or deleted outright, it highlights the individual words that differ — which is what turns “this line changed” into “this one word changed”. Line numbers are tracked separately for each side, so you can find the spot in your real file.

Everything runs locally with JavaScript — nothing is uploaded, and there is no signup or daily limit. If you need to clean up the text first, the extra space remover and duplicate line remover pair well with this one.

Frequently asked questions

Paste the original version in the left box and the changed version in the right box. The comparison updates as you type — added lines are highlighted in green, removed lines in red, and changed lines show the specific words that differ.

Side by side shows both versions in two columns, which is easier for reading prose and spotting reworded sentences. Unified stacks everything in one column with + and − markers, the same layout git and code review tools use, which suits long files and narrow screens.

Yes. Ignore case treats “Cat” and “cat” as identical. Ignore whitespace trims leading and trailing spaces and collapses runs of spaces and tabs, which is useful when comparing reformatted or re-indented text.

Yes. Indentation is preserved and the comparison is line based, so it works for source code, JSON, CSV, configuration files and logs as well as prose. Windows and Unix line endings are normalised first, so a file saved on Windows will not show up as entirely changed against the same file saved on Linux.

No. The whole comparison runs in your browser with JavaScript. Nothing is sent to a server, which means you can safely compare contracts, medical notes, source code or anything else confidential.

There is no hard limit, but very large texts with a large number of differences fall back to a coarser comparison so your browser stays responsive. When that happens the tool tells you, rather than presenting an approximate result as if it were exact.