Diff Checker
Compare two texts and highlight differences
Paste two versions of a file or text block and see exactly what changed line by line. Character-level diffing pinpoints the specific words or symbols that differ within a changed line. Useful for comparing config files, API responses, or scraped page content across separate runs.
Original
Modified
How to use
- 1Paste the first version — In the left panel — the original or earlier version.
- 2Paste the second version — In the right panel — the modified version.
- 3Get results — In auto mode, the diff updates as you type. Disable auto mode to run manually with Run. Additions are highlighted green, deletions red.
- 4Choose highlight mode — Auto (default) — character-level for short lines, word-level for long ones. Characters — highlights each changed character, useful for finding typos. Words — highlights changed words and tokens, useful for JSON and code.
Examples
Compare HTML from two scraper runs
run_1.html vs run_2.htmlCompare HTML from two runs — find new elements and class changes without writing a script.
Compare two API responses
response_v1.json vs response_v2.jsonCompare two API responses — find added or removed fields after an update without a script.
Compare config files
config.old.json vs config.new.jsonCheck config changes — find the difference without git and without extra tools.
Two JSON responses with different parameters
api?page=1 vs api?page=2Confirm that two API responses with different parameters have the same structure — without writing comparison code.
HTML before and after deploy
index_before.html vs index_after.htmlCheck markup after deploy — find broken scraper selectors before the next crawler run.
When to use for web scraping
In scraping, diff is essential for monitoring changes: if the same URL is scraped daily, diff shows exactly what changed — new products appeared, prices changed, a section disappeared. This is the foundation of change-detection scrapers. Also useful for debugging: take HTML from yesterday and today, compare — and immediately see what broke the selectors.
FAQ
Is there a line-by-line and character-level mode?›
Yes. Changed lines are highlighted in full, and within them — the specific changed characters. This helps find a typo in a long line.
Are whitespace differences counted?›
Yes, by default. If you need to ignore whitespace and indentation, pre-process the input (paste both texts without extra whitespace).
How do I compare two HTML responses from different API versions?›
Make two requests via Request Tester, copy each response body into the left and right panels of Diff Checker. The tool immediately shows added, removed, and changed lines — without writing comparison scripts.
Is Unicode comparison supported?›
Yes. Cyrillic, Chinese characters, emoji, and other Unicode symbols are compared correctly. Character mode also works with multi-byte characters.
Why does the tool show changes where I don't see any?›
Most often the cause is invisible characters: trailing spaces, carriage return characters (\r\n vs \n), or Unicode spaces. Character mode will show the exact character that differs.