ABOUT THIS TOOL
Content Changes Made Visible
WhatTheDelta is a private, browser-based text comparison tool for reviewing visible changes clearly and without sending content to a server.
It is designed for review work where small wording shifts, changed figures, or structural edits can matter more than they first appear. By making visible changes easier to inspect, it helps reduce review friction without trying to replace human judgment.
- Runs locally
Runs locally
The comparison happens in your browser on your device.
- No account
No account
You can use the tool directly without creating a login.
- No AI
No AI
The comparison is rule-based and deterministic.
- Works broadly
Works broadly
Useful across languages and for structured text such as code.
- Free forever
Free forever
Use it freely, but please do not abuse the service.
What you can use it for
WhatTheDelta is designed for anyone who needs to compare two versions of content quickly and clearly.
reviewing revised contracts, clauses, and policy drafts
checking changes in legal, compliance, procurement, or internal documentation
comparing edited website copy, newsletters, press releases, and product text
reviewing rewritten client deliverables, internal notes, or translated content
checking AI-generated rewrites or edits against the original version
spotting changes in dates, figures, wording, structure, or punctuation before sign-off
reviewing edited emails, client messages, or internal communication
comparing structured text such as code, configuration snippets, or technical content
WhatTheDelta is language-agnostic. It focuses on visible changes between two versions of content and can be used with many languages and content types.
WhatTheDelta helps you spot:
additions and removals
light rewrites
broader rewrites
dates, numbers, and values
punctuation-only differences
paragraph and document-flow changes
WhatTheDelta does not:
upload, save, or share your text
replace legal or editorial review
approve or judge changes
infer intent behind rewrites
convert files or process uploads
perform semantic analysis
Install it like an app
WhatTheDelta can also be installed for quicker access and a more app-like experience on devices that support Progressive Web Apps.
on Mac, add it to the Dock from a supported browser
on iPhone or iPad, add it to the Home Screen from Safari
on Android, install it from the browser menu or add it to the Home Screen
on supported desktop browsers, install it or create an app-style shortcut
Once it has been loaded on a device, the app can also keep working offline.
Quick FAQ
A few practical questions come up again and again when people first use the tool.
Does my text leave the browser?
No. The comparison runs locally in your browser, and the text remains there only for the active session.
Is AI involved?
No. WhatTheDelta does not use AI or generative models. The comparison is rule-based and deterministic.
Can I use it with different languages?
Yes. WhatTheDelta is language-agnostic and compares visible differences between two versions of content. It can be used with many languages and with structured text such as code.
Can I use it to review AI output?
Yes. It can be useful for checking AI-generated rewrites, edits, or reformulations against an original version so changes are easier to inspect.
Why does a paragraph appear as lightly reworded or material?
Changes are grouped by visible effect. Smaller wording edits stay in a lighter review category, while broader rewrites, additions, and removals are marked more strongly.
Can I ignore punctuation, case, or whitespace differences?
Yes. You can hide punctuation-only changes and ignore case or whitespace differences when that makes the review clearer.
When should I use chunk view or whole document view?
Use chunk view when you want to locate and filter changed sections quickly. Use whole document view when you want to read the revised text as a continuous flow with inline evidence.
How much text can I compare at once?
There is no server-side comparison limit in the workflow, but very long texts can feel slow on older devices or constrained browsers because everything runs locally. If review becomes heavy, split the text into smaller sections or compare large documents across multiple tabs.
Which browsers are supported?
WhatTheDelta is built for modern browsers. The current Next.js support baseline covers Chrome 111+, Edge 111+, Firefox 111+, and Safari 16.4+.
Best practice tips
A few small habits make the output easier to trust and easier to review.
paste a clean original and a clean revised version
start with chunk view to locate changes quickly
switch to whole document view when reading flow matters
use ignore options only when they remove noise relevant to your review
split very long documents into smaller sections when review starts to feel slow
treat the tool as a fast comparison aid and make the final decision in context
Important note
Disclaimer
WhatTheDelta is provided as a helper utility for comparing two versions of content. It is intended to support review work, not replace professional judgment.
You remain responsible for how you use the tool and for any decisions made on the basis of its output.
Further details on permitted use, liability, and legal terms are set out in our Terms of Use.