Diff checkerValidators

Diff checker. See what changed, line by line.

Paste the original and the changed text. Added lines show in green, removed lines in red, and the words that changed inside a line are marked. Ignore whitespace or case when they do not matter. Up to 500,000 characters per side.

Cost to you

Free

Runs in your browser. No signup, no API call, no limit per hour.

browser
runs in
none
API calls
none
account

Use it now

Use the Diff checker here

It runs in your browser. Nothing you type is sent anywhere, there is no signup and no limit.

Loading the tool.

Run it from your agent

Copy one prompt, give it to your agent.

Fill in the placeholder, paste it, and the agent runs the same job with current data on your looot account and shows the cost.

  • You give it: two blocks of text.
  • Billed per call, nothing while your agent is idle.
  • The agent shows the price before it calls.
Prompt: Diff checker
Use looot to see what changed on a web page since my last check. 1. Set up https://looot.ai/skill.md. 2. Search the catalog for an endpoint that returns a page as markdown and check its price before you call. 3. Fetch [URL] and save the markdown. 4. Compare it with the copy I paste here: [old text]. 5. List the added and removed lines and sum up the change in two sentences.

Give this to your agent
Setup command
set up looot - https://looot.ai/skill.md

What comes back

What your agent gets from diff checker

Field names as the providers return them. The exact set varies by endpoint, and your agent reads it from the catalog.

  • side by side diff
  • inline diff
  • added and removed line counts
  • unified diff text

Use it for

What people do with diff checker

  • Review a change

    Compare two versions of a config, a contract or a prompt before you ship it.

  • Check agent edits

    See exactly what an agent rewrote in a file or a draft.

  • Compare exports

    Paste two CSV or JSON exports and find the rows that moved.

  • Page changes

    Diff two copies of a web page's text to see what the site changed.

Set up once

Three steps. Your agent does the rest.

Keep going

More free tools

FAQ

Questions about diff checker

Paste the first version on the left and the second on the right. The result updates as you type. Swap sides flips which one counts as the original.

The Myers algorithm, the default in git diff. It finds the smallest set of added and removed lines that turns one text into the other. Changed words inside a line are found the same way at word level.

Yes. Ignore whitespace treats runs of spaces and tabs as one and skips spaces at line ends. Ignore case compares letters without case. Windows and Unix line endings always compare equal.

Up to 500,000 characters per side. Two long texts with a few changes compare quickly. Two long texts that share almost nothing can hit the edit limit, and the page then asks you to compare a smaller part.

Copy diff and the .diff download give the comparison as unified diff lines, with - for removed and + for added. The output has no hunk headers, so git apply will not take it as a patch.

It compares text you paste. Open each file, copy its text into one side. For whole folders use git diff or diff -r on your machine.

No. The comparison runs in your browser. Nothing you paste is sent or stored.
For agents
tool
Diff checker
category
Validators
input
Two blocks of text
output
side by side diff, inline diff, added and removed line counts, unified diff text
price
per call, read live from the catalog on the web page
web tool
runs in the visitor's browser, no API call, free and unlimited
schedule
on demand
setup
https://looot.ai/skill.md
llms.txt
https://looot.ai/llms.txt
updated
2026-10-14
markdown /free-tools/diff-checker.md

Run diff checker from your own agent.

Start your workspace, top up, and paste the prompt into the agent you already use. It runs the job with live data and shows the cost first.

Start your workspace See all free tools