Utiltown

Text Diff Checker

Use this diff checker for fast text comparison: compare two texts and see exactly what changed — line by line or character by character — with clean highlights. Runs entirely in your browser, so nothing is ever uploaded. To edit either side in place, try the Text Merge Editor.

All computations run locally in your browser, no data uploaded to server. 
 
  
  
 
How To Use
 
     
  1. Paste the Original text and the Compared text into the two boxes.
    2.  
  2. The diff appears automatically as you type — no button needed.
    3.  
  3. Optionally tick Ignore case or choose a Whitespace level (Off / -b ignores spacing changes / -w ignores all spacing) to hide cosmetic-only differences.
    4.  
  4. Read the two panes side by side with line numbers: Line mode marks each changed whole line (removed on the left, added on the right; the +/- symbol and left bar show it even without color); Character mode also underlines the exact changed characters inside a line. The badge above the result counts additions/removals.
    5.  
  5. In long files, jump straight to any edit: click a Changes chip (or the ‹ › buttons) above the result, or use the change map on the result's left edge — colored ticks show where every change sits and a slider tracks your viewport.
    6.  
  6. Use Compare to re-run instantly (e.g. after a large paste), Swap sides to flip the direction, then Copy output to grab a plain-text version.
    7.  
 
 
 
Usage Example
 
Original text:
 
alpha
beta
gamma
delta
 
Compared text:
 
alpha
BETA
gamma
omega
delta
 

The result is shown side by side: the Original pane on
        the left shades beta as removed (red) and the
Compared pane on the right shades BETA +
omega as added (green); the shared lines
alpha, gamma, and delta stay
        plain. In Character mode the changed characters inside
        a line are additionally marked.

 

Want a richer sample? Click Demo above the result: it
        loads a realistic deploy-config before/after with additions, removals
        and edits spread across several change blocks — a good way to see the
        Changes chips, the change map, and Character mode's character-level
        highlights in action.

 
 
 
Frequently Asked Questions
  
Is my text uploaded to a server?
 
No. The diff runs entirely in your browser. Nothing is sent anywhere, so it is safe to compare sensitive or proprietary text.
  
What is the difference between Line and Character mode?
 
Line mode compares whole lines and marks each changed line in the matching pane (removed on the left, added on the right), which is best for readable documents or code. Character mode additionally drills into a changed line and marks the exact characters that differ, which can be noisy but catches typos in long strings.
  
How do I read the highlighted result?
 
The result renders both boxes side by side with line numbers. Text present only on the left stays in the Original pane (removed); text present only on the right appears in the Compared pane (added); unchanged lines are unmarked. Colour never carries the meaning alone — changed rows also show a leading +/- symbol and a left colour bar, and in Character mode the changed characters are underlined so the exact edit is easy to spot.
  
Is the comparison case-sensitive?
 
It is by default. Tick "Ignore case" so that "Beta" and "beta" are treated as identical. The Whitespace option has three levels: Off compares spacing exactly; "Ignore whitespace changes (-b)" collapses runs of spaces/tabs into a single space and ignores trailing whitespace (so extra spaces and tabs-vs-spaces no longer count, but an inserted space inside a word still does); "Ignore all whitespace (-w)" removes every space entirely, so "asd" and "a sd" are treated as identical.
  
How large can the inputs be?
 
The tool uses an exact diff and will refuse inputs that are too large to compute instantly in the browser, so it stays snappy without freezing your tab.
  
How do I jump between changes in a long file?
 
Long files no longer mean endless scrolling. The "Changes" chips above the result list every change block with its line range and −/+ counts — click one to jump straight there, or step through with the ‹ › buttons. Along the left edge of the result there is also a mini change map: every change is a colored tick (red = removed, green = added, amber = modified) placed exactly where it sits in the file, next to a slider showing your current viewport. Click or drag on the map to scroll, and it highlights the block you are in as you move. This at-a-glance change navigation is something most online diff tools do not offer.
  
Can I get a plain text copy of the diff?
 
Yes. Click Copy output to copy the result — lines are prefixed with "- " or "+ " so you can paste it anywhere, including into a diff-aware tool.
  
 
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