Text Diff Compare

Compare Two Texts and Highlight Differences Instantly

"How do I compare two pieces of text and see what changed?" Paste your original in the left box and the new version in the right box, then click Compare Texts. This text diff tool highlights every insertion in green and every deletion in red — word by word — so you can spot revisions, typos, and missing passages at a glance. Everything runs in your browser. Nothing you paste is sent to a server.

How to Compare Two Text Files Online

There are three reliable ways to diff two texts — one fast, two manual.

1. Use the Text Diff Checker above (fastest)

Paste the original text on the left and the new text on the right, then hit Compare Texts. The tool runs a word-level comparison and renders a single merged view with removed text struck through in red and added text highlighted in green. Hit Edit Texts to go back and adjust either side without losing your input.

2. Compare two files in Notepad++ (Windows, offline)

If you want a desktop workflow:

1. Install the Compare plugin from Notepad++'s Plugins Admin.
2. Open both files in separate tabs.
3. Go to Plugins → Compare → Compare. Differences show side-by-side with line-level markers.

Good for large files, but it compares line-by-line only, not word-by-word, so small inline edits get flagged as whole-line changes.

3. Use VS Code's built-in diff

Open both files in VS Code, right-click the first in the Explorer and choose Select for Compare, then right-click the second and choose Compare with Selected. VS Code shows a split diff. Like Notepad++, it's line-oriented — useful for code, less readable for prose.

The tool above is browser-based, word-level, and needs no install — better suited to prose, drafts, and short snippets.

What the Diff Checker Detects

For any two texts, the comparison reports three change types:

1. Insertions — words present in the new text but not the original, highlighted green.
2. Deletions — words present in the original but not the new text, shown red with a strikethrough.
3. Unchanged text — words that match in both versions, rendered as plain text so edits stand out.

The algorithm uses the Longest Common Subsequence (LCS) approach, which finds the largest block of matching words between the two texts and treats everything else as insertions or deletions. It splits on whitespace, so comparisons stay readable even for paragraphs of prose.

Common Uses for a Text Compare Tool

• Editors and writers — compare draft revisions to spot deleted sentences, tone shifts, or accidental cuts between versions.
• Developers — diff code snippets, config files, SQL queries, or JSON payloads when Git or your IDE isn't handy.
• Translators — line up source and translated text to confirm nothing was skipped.
• Legal and contracts work — redline changes between two versions of a clause without uploading sensitive documents anywhere.
• Students and researchers — check what a co-author edited in a shared draft.

If you also need word or character counts for either version (for SEO meta lengths, tweet limits, or essay requirements), pair this with the text count checker.

Diff Checker vs Similarity or Plagiarism Checker

A diff checker answers what specifically changed between two known versions — it aligns words and highlights edits. A similarity or plagiarism checker answers how much overlap exists between a document and a corpus, returning a percentage score. Use a diff tool when you have two versions of the same text. Use a similarity checker when you're comparing unrelated documents for originality.

Is It Safe to Paste Sensitive Text Into a Diff Checker?

This tool runs entirely client-side — the comparison algorithm executes in your browser and no text is transmitted to a server. That makes it safe for confidential drafts, contract clauses, unpublished code, and internal documents. If you close the tab, the text is gone. For online diff tools that do send text to servers (check their privacy policy), avoid pasting anything you wouldn't want logged.