About Text Diff Checker — Compare Two Texts Online
A text diff compares two blocks of text and shows exactly what changed — which lines were added and which were removed. It's the fastest way to review an edit, spot config drift between two environments, compare two API responses, proofread successive drafts, or confirm that a copy change landed the way you intended.
This free text diff tool compares your Original and Changed text line by line, colour-coding additions in green and removals in red with familiar +/- markers. It runs entirely in your browser — nothing you paste is ever uploaded — so it's safe for code, secrets, and anything else you'd rather keep on your own device.
Features
- Side-by-side input for the original and changed text
- Line-by-line diff with green additions and red removals
- Live added / removed counts as you type
- Fully offline — your text never leaves the browser
How to use
- Paste the original text into the left pane.
- Paste the changed version into the right pane.
- Read the diff below: + marks added lines, - marks removed lines.
Frequently asked questions
How does the line diff work?
It computes the longest common subsequence of the two inputs at the line level, then marks lines that only appear in the original as removed and lines that only appear in the changed text as added. A modified line shows up as a removal plus an addition.
Is my text sent to a server?
No. The comparison runs entirely in your browser using local JavaScript. Nothing you paste is uploaded, which makes it safe for code, configuration, and sensitive content.
Does it do word-level or character-level diff?
The comparison is line-level: each line is treated as a whole unit, so a change anywhere in a line marks the entire line as removed and re-added. It does not highlight the individual words or characters that changed within a line.
What counts as a difference?
Differences are detected per line. Two lines must match exactly — including whitespace and letter case — to be treated as unchanged, so even small edits within a line are surfaced as a removed line and an added line.
Related tools
Everything runs locally in your browser — your input is never uploaded.