🔍Text Diff Checker
Paste two texts and see every difference highlighted — line by line, right down to individual words.
Text diff checker online — compare two texts instantly
Need to spot what changed between two versions of text? Our free text diff checker online highlights every difference instantly. Paste your original text on one side and the updated version on the other, and it shows exactly what was added, removed, or changed — line by line, and right down to the individual words within a line. No more squinting to find the one edit that matters.
Switch between a side-by-side view and an inline unified view, and fine-tune the comparison by ignoring case or whitespace when you only care about real changes. A clear summary tells you how many lines were added and removed at a glance. Whether you're comparing drafts, reviewing code or config changes, checking edits to a document, or proofreading, the differences jump straight out. Simply paste two texts to compare them instantly. No sign-up, no downloads, no limits — just clear results, privately.
About the Text Diff Checker
How diffing works
The tool uses the Longest Common Subsequence (LCS) algorithm to identify the largest set of lines that appear in both texts in the same order. Lines not in the common sequence are classified as deletions (in the original only) or additions (in the changed version only). For lines that were modified rather than simply added or removed, a second LCS pass runs on the words or characters within those lines to pinpoint the exact changed segments.
Features
Line-level diff
LCS algorithm finds the minimal set of changes across all lines.
Word & char diff
Highlights the exact words or characters that changed within a modified line.
Side-by-side view
Two aligned columns so you can read original and changed versions together.
Inline view
Unified diff stream with − and + markers — the format familiar from git diff.
Ignore case & whitespace
Filter out formatting noise so only meaningful changes show up.
Change summary
At-a-glance +N / −M count of lines added and removed.
Copy unified diff
One click copies a standard unified diff patch to your clipboard.
Fully private
No server, no storage — everything runs in your browser.
Accessibility
Added and removed lines are marked with + and − symbols in addition to color coding, so the diff is readable for users who cannot distinguish red from green. Color is used as a reinforcement, not as the sole signal.
Frequently Asked Questions
How does the text diff checker work?
Paste your original text in the left pane and the changed text in the right pane. The tool computes the differences using the Longest Common Subsequence (LCS) algorithm and highlights every addition, deletion, and change — updating automatically as you type.
Is the text diff checker free?
Completely free, with no sign-up, downloads, or limits on how much text you can compare.
Can it show differences within a line?
Yes. When the Sub-line option is set to Word or Char, the tool highlights the exact words or characters that changed within a modified line — not just that the line changed. Switch to None to see only line-level differences.
What view modes are available?
There are two view modes. Side by side shows the original and changed text in two aligned columns so you can read both simultaneously. Inline (unified) shows all changes in a single stream with − and + markers for removed and added lines.
Can I ignore case or whitespace?
Yes. Toggle Ignore case to treat upper and lower case letters as equal. The Whitespace option lets you keep whitespace as-is, trim leading/trailing spaces from each line, or ignore all whitespace entirely — so only meaningful content changes appear.
What does the summary line show?
The summary shows the total count of added lines and deleted lines in the format +N / −M. If both texts are identical, it shows "Identical" instead.
Can I use it to diff code or config files?
Yes — it works on any plain text, including source code, JSON, YAML, environment files, and other configs. Paste the file contents into each pane and the diff highlights every change.
Is my text sent to a server?
No. All diffing runs entirely in your browser using JavaScript. Nothing you paste or type is sent anywhere, so your content stays completely private.
What is the Copy unified diff button?
It copies a unified diff string to your clipboard — the standard format used by version-control tools like git diff, with − lines for deletions and + lines for additions. You can paste this into a PR description, bug report, or any tool that accepts diff patches.
Does it work on mobile?
Yes, the tool is fully responsive. On small screens the two input panes stack vertically and the diff output adapts so there is no horizontal overflow.