Diff Checker
Free · no signup · runs entirely in your browser
Open the tool →Two versions of the same document. A config file before and after someone "fixed" it. A paragraph you edited and want to know what actually moved. Eyeballing two text blocks for differences is a great way to miss the one line that matters — this tool does the eyeballing for you.
Paste your original text on the left, your modified version on the right, hit Compare, and it walks through both line by line. Lines that match print as-is. Lines that differ show up as a removed line (marked with a minus, in the removed color) followed by the added line (marked with a plus, in the added color) — the classic diff-style output you've seen in git or a patch file, without needing git installed.
It's a straightforward line-by-line comparison: it checks each line position against the other text's line in that same position. That makes it fast and easy to read for edits, reorders of a few lines, or config tweaks, though it's worth knowing it's comparing by line index rather than running a full alignment algorithm — if you insert a line near the top of a long document, everything below it will show as changed too, same as any simple diff. For most real use — checking what changed in a short doc, a code snippet, a list, an email draft — that's exactly what you want.
No signup, no file upload to some server, no ads wrapping your text. Paste, compare, read the diff, done. Runs entirely in your browser tab.
How to use it
- Paste your original text into the ORIGINAL box on the left.
- Paste the updated version into the MODIFIED box on the right.
- Click COMPARE — lines that changed are marked with a minus (removed) or plus (added); unchanged lines print plain.
Worked example
Original: "Server restarts at 4am\nBackups run nightly\nContact: [email protected]". Modified: "Server restarts at 4:20am\nBackups run nightly\nContact: [email protected]". Comparing shows line 2 ("Backups run nightly") unchanged, and lines 1 and 3 each show a removed line followed by the added replacement — so you instantly see the restart time and contact email changed, without re-reading the whole block.
FAQ
Does it compare word-by-word or character-by-character?
No — it compares line by line. If anything on a line changes, that whole line shows as removed and re-added, not just the changed word.
Can it diff two files, not just pasted text?
Paste the file contents into the two boxes — there's no file-upload option, which also means nothing you're comparing ever leaves your browser.
Why did every line after my edit show as changed?
The comparison lines up text by line position (line 1 vs line 1, line 2 vs line 2, and so on). Inserting or deleting a line near the top shifts every line below it out of alignment, so they'll all show as different even though the content just moved down.
Is this free and does it need an account?
Free, no signup, no limit on how many times you compare. It's one of 115+ tools on Gibbler and runs entirely client-side.
Open the Diff Checker →