Paste two texts to compare them line by line, word by word or character by character. The Diff Checker uses the same Myers-family algorithm git uses and reports added and removed counts. Characters mode is capped at 200,000 characters per side. Both sides stay in this tab; nothing is uploaded.
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A diff checker shows what changed between two versions of a text: config files, contracts, SQL dumps, API responses, a paragraph someone edited. Paste both versions, press Compare and every change is highlighted (removed parts in red, added parts in green) at the granularity you pick: whole lines, single words or single characters. In Lines mode a modified line also gets its changed words highlighted, so a one-token edit inside a long line stands out.
Both texts are compared with the diff library's Myers algorithm, the same family git uses. Lines mode runs diffLines, then pairs each removed block with the added block that directly follows it when both have the same line count and runs a word diff inside every pair. Words mode runs diffWords and Characters mode diffChars; Characters mode is capped at 200,000 characters per side and falls back to Words above that. The status bar reports added and removed counts and the share of characters unchanged: unchanged characters divided by the length of the longer text. Everything runs in this tab.
Characters mode is capped at 200,000 characters per side and falls back to Words above that.
~/faq
Paste the first version under Original and the second under Changed (or drop a file on either side) and press Compare (Ctrl or Cmd + Enter also works). Removed parts show in red, added parts in green. Pick Lines for code and config files, Words for prose, and Characters for short strings such as keys, IDs or URLs.
Lines treats each line as one unit, so a one-letter edit marks the whole line as removed plus added, with the changed word highlighted inside it. Words splits the text into words and punctuation, so only the edited words are marked and reflowed paragraphs still compare cleanly. Characters marks individual characters, which is exact but noisy on long texts; it is capped at 200,000 characters per side.
Yes for code: Lines mode is the same class of diff git shows, and the ignore-whitespace toggle hides indentation-only changes. For JSON, a text diff reports reordered keys and reformatting as changes. Use the JSON Diff at localfirsttools.com/json-diff instead: it parses both documents and compares them structurally, so key order and whitespace produce no differences.
Only when the toggle is on. In Lines mode it ignores leading and trailing whitespace on each line (indentation and trailing spaces) but not spacing inside a line. Words mode always ignores whitespace between words. Characters mode collapses runs of spaces and tabs to one space and trims line ends before comparing, and says so under the diff.
No. The diff runs in this tab with the diff JavaScript library. LocalFirstTools has no server endpoint that receives the text you paste, and a dropped file is read with the browser's FileReader without leaving your device.
Chosen for the same job, not just the same category.