Text diff checker
Compare two blocks of text line by line.
The text diff checker compares an original and a modified block of text line by line, marking which lines were added, removed, or left unchanged — a quick way to see exactly what changed between two versions.
How to use
- Paste the original text on the left and the modified version on the right.
- Click "Compare" to see a line-by-line diff — added lines are highlighted one way, removed lines another.
- Lines that only moved position (without changing content) may show as both removed and added.
Common use scenarios
- Comparing two drafts of a document to see what was edited.
- Checking whether a config file or code snippet changed between two versions.
- Reviewing what a collaborator changed in shared text.
- Confirming two supposedly identical blocks of text are actually the same.
✓Content & verification reviewed: 2026-08-25
How we verify Text diff checker
How to read the diff output correctly.
Comparison is line-by-line, not character-by-character
A single-character change inside a long line marks that entire line as changed (shown as one removed line and one added line) — the tool doesn't highlight exactly which characters within the line differ.
A moved line can show as both removed and added
If a line's position shifts without its content changing, the diff algorithm may still show it as removed from its old position and added at its new one, since it compares based on matching content in sequence, not tracked identity.
Line-ending style affects what counts as a line
The text is split into lines the same way regardless of Windows (CRLF) or Unix (LF) line endings, but if one version was edited with different line-wrapping than the other, that alone can produce more diff lines than the actual content change.
Before you rely on the result
- You understand a small in-line edit still marks the whole line as changed.
- You've considered that a moved-but-unchanged line might appear as both removed and added.
- For very large inputs, you're aware comparison may take a moment.
- You're comparing the intended two versions in the right original/modified order.
Who this is for
- Anyone comparing two drafts of a document.
- People checking whether a config file or snippet changed between versions.
- Anyone reviewing what a collaborator changed in shared text.
- People confirming two blocks of text are actually identical.
Real-world examples
Reviewing a document revision
Someone comparing an old and new draft of a policy document pastes both in to quickly see which paragraphs were added or removed.
Checking a config change
A person suspecting a configuration file changed unexpectedly pastes the old and new versions to confirm exactly which lines differ.
Confirming two texts match
Someone who copied text from two sources pastes both in to confirm they're identical before treating them as interchangeable.
Limitations
- Comparison is line-by-line, not word-by-word — a one-character change in a long line marks the whole line as changed. Very large inputs (many thousands of lines) may be slow.
Frequently asked questions
Does it highlight the exact word that changed within a line?
No — comparison is line-by-line, so a one-word change in an otherwise identical line still marks that whole line as removed and added.
Why does a line that didn't really change show up as a diff?
That can happen if the line moved position — the algorithm matches lines by content in sequence, not by tracking each line's identity, so a relocated line can appear as removed from one spot and added at another.
Will this work on very large files?
It can, but comparison time grows with the size of both texts — expect it to slow down noticeably on inputs with many thousands of lines.
What does it mean if no differences are found?
It means the two texts are exactly identical line-for-line, including line breaks — even a trailing blank line difference would show up as a change.
🔒 Runs in your browser — nothing is uploaded. Results are for reference only; see the disclaimer. Last updated: 2026-08-25
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