Text Compare

Tool Overview

This text compare tool shows the differences between two pieces of text. You paste or type an original text and a changed text. The tool highlights what was added, removed, or left the same and gives you a short summary of how many changes there are.

People often need to see what changed between two versions of a document, a contract, or code. Reading both versions by hand is slow and easy to get wrong. This tool solves that by running a comparison and marking additions and deletions so you can scan the result quickly.

The tool is for anyone who needs to compare two texts. Writers use it to see edits. Developers use it to check code changes. You do not need technical skills. You paste the two texts, set options if you want, and read the highlighted result and the summary.

Background & Concept Explanation

Comparing two texts means finding where they differ. A diff tool splits both texts into pieces (for example by line or by word), aligns them, and marks each piece as added, removed, or unchanged. Added means it appears only in the second text. Removed means it appears only in the first. Unchanged means it appears in both. The result is one stream of segments so you can read from top to bottom and see what changed. A related operation involves comparing JSON structures as part of a similar workflow.

Diffs are used in many places. Editors compare drafts. Programmers compare code before and after a change. You might compare two contracts or two lists to see what was added or removed. Without a tool you would have to read both versions and remember or underline differences yourself.

People struggle when they compare by eye. They miss small changes. They get confused when only spaces or capital letters change. This tool can ignore whitespace or ignore case so that only meaningful differences are highlighted. You can also choose to compare by line or by word so the result fits how you think about the text.

The tool runs in your browser. Nothing is sent to a server for the comparison itself. Only if you ask for an AI explanation are the two texts sent to a backend. The comparison and summary are done locally from your input. For adjacent tasks, removing duplicate lines addresses a complementary step.

Key Features

• Two text areas let you enter the original text and the changed text. You paste or type in the first box for the original version and in the second for the modified version. Each box has a character limit of 500000 characters. A counter shows how many characters are left; when you are close to the limit it turns red. This keeps the tool responsive and prevents overload.
• Comparison runs automatically when both texts are short enough. If each text is under 5000 characters, the tool compares them automatically after a short delay when you stop typing. If either text is 5000 characters or longer, the tool does not run the comparison and no result is shown until you shorten the input. This avoids freezing the browser on very long texts.
• Three comparison modes change how the text is split and compared. Quick mode compares by line and collapses long runs of unchanged lines into a single line like five unchanged lines so the result is shorter. Line mode compares by line and shows every line. Word mode compares by word so you see changes inside a line. You choose the mode with buttons at the top. This lets you switch between a quick overview and a detailed word-level diff.
• Ignore whitespace is an option. When it is on, the tool normalizes spaces and line breaks before comparing. Multiple spaces become one space and leading and trailing spaces are trimmed. The result still shows the original text with the original spacing; only the comparison logic ignores whitespace. This helps when the only differences are spaces or tabs.
• Case sensitive is an option. When it is on, uppercase and lowercase are treated as different. When it is off, the tool compares without caring about case but still shows the original text in the result. This helps when the only differences are capital letters.
• The diff view shows one combined result. Added parts are highlighted in green with a green border. Removed parts are highlighted in red with a red border and a line through the text. Unchanged parts are shown in gray at lower opacity. A legend at the bottom explains the colors. You read from top to bottom to see the full text with changes marked. This makes it easy to see what was added or removed at a glance.
• A summary panel shows counts. It displays how many additions, how many deletions, and how many modifications. A modification is counted when an added part immediately follows a removed part. It also shows a similarity value: 100% if the texts are identical, otherwise a lower percentage based on the number of changes. This gives you a quick sense of how different the two texts are.
• Previous and Next buttons let you jump between changes. When there are changes, you can click Previous or Next to move from one change to another. The current change is highlighted and the view scrolls to it. A counter shows which change you are on and how many there are. This helps when the result is long and you want to move through changes one by one.
• Swap exchanges the two texts. You can click the swap button to put the original text in the changed box and the changed text in the original box. The comparison runs again with the new order. This is useful when you pasted them in the wrong order.
• Clear removes both texts and resets the result. You can start over with a new pair of texts. Optional AI explanation sends both texts to a backend and shows a short explanation of the differences. You click a button to request it. If it fails, you may see an error such as insufficient credits. The comparison and summary do not depend on the AI; they work without it.

Common Use Cases

Writers compare two drafts of an article or report. They paste the old version in the original box and the new version in the changed box. They use line or word mode to see exactly what was added or removed. Ignore whitespace helps when the only edits are formatting.

Developers compare two versions of code or config. They paste the old and new content and use line mode to see added and removed lines. The summary tells them how many lines were added, removed, or modified. They use Previous and Next to jump through changes.

Anyone comparing contracts or lists uses the tool to see what changed between two versions. They paste both texts and read the highlighted result. The similarity percentage gives a quick idea of how much changed. Swap is useful if they pasted the versions in the wrong order. When working with related formats, finding and replacing text can be a useful part of the process.

Students or editors can use the optional AI explanation to get a short summary of the differences in plain language. They run the comparison first, then click to generate the explanation. The comparison itself does not require AI.

How to Use This Tool

1. Open the text compare tool in your browser.
2. Paste or type the original text in the left box labeled Original. Paste or type the modified text in the right box labeled Changed. Each box accepts up to 500000 characters. Watch the character counter if you paste very long text.
3. Choose comparison options. Use the Quick, Line, or Word buttons to set the mode. Check Ignore WS if you want to ignore spaces and line breaks when comparing. Check Case if you want to treat uppercase and lowercase as different; uncheck to ignore case. Use the swap button if you need to swap the two texts.
4. Wait for the result. If both texts are under 5000 characters, the tool compares them automatically after you stop typing. The summary panel appears with Added, Removed, Modified, and Similarity. The diff view appears below with green for added, red for removed, and gray for unchanged. If either text is 5000 characters or more, no result is shown; shorten one or both to get a comparison.
5. Read the diff. Scroll through the result. Use the legend at the bottom to confirm what green and red mean. Use the Previous and Next buttons to jump from one change to the next. The current change is highlighted.
6. Optionally click Generate Explanation to get an AI-written summary of the differences. Wait for the response. If you see an error such as insufficient credits, the comparison and summary are still valid. You can reset the explanation and try again later.
7. To compare a new pair of texts, click Clear. Both boxes are emptied and the result is reset. Paste or type the new texts and repeat.

Calculations & Logic

The tool uses a diff library to compare the two texts. Depending on the mode, it splits the text into lines or words. It then runs a standard diff algorithm to find the longest common parts and marks the rest as added or removed. The result is a list of segments. Each segment has a value (the text) and a flag for added or removed. Unchanged segments have no flag. In Quick mode, when more than five unchanged lines appear in a row, they are replaced by a single line that says how many unchanged lines were skipped. The displayed text in the result is always the original text from your input; only the comparison may use normalized text when ignore whitespace or case insensitive is on.

The summary is computed from the list of segments. Each segment marked added counts as one addition. Each segment marked removed counts as one deletion. When an added segment immediately follows a removed segment, the pair counts as one modification and the addition and deletion counts are adjusted so that the total changes are not double counted. Total changes is the sum of additions, deletions, and modifications. Identical is true when total changes is zero. The similarity percentage shown is 100% when identical; otherwise it is 100 minus twice the total changes, rounded to an integer and not allowed to go below zero. This is a simple heuristic so you can see roughly how similar the two texts are. In some workflows, encoding data in Base64 is a relevant follow-up operation.

Input length is limited. If either text is longer than 500000 characters, only the first 500000 characters are used for the comparison. The text areas also enforce a maximum length so you cannot type or paste more than that. Auto-compare runs only when both texts have fewer than 5000 characters; above that, no comparison is run so the tool stays responsive.

Reference Tables or Scales

Comparison modes:

Options: For related processing needs, viewing Git diffs handles a complementary task.

Limits:

Tips, Limitations & Best Practices

Keep both texts under 5000 characters if you want automatic comparison. For longer texts the tool will not show a result until you shorten them. For very long texts consider comparing in chunks or using a desktop diff tool.

Use Ignore WS when the only differences are spaces, tabs, or line breaks. Use case insensitive (Case unchecked) when the only differences are capital letters. That way the highlight focuses on the changes that matter to you.

Use Quick mode for a short overview when there are long unchanged sections. Use Line mode when you need to see every line. Use Word mode when you care about changes inside a line.

AI explanation is optional and can fail. You may see an error about credits or connection. The comparison and summary do not depend on it. You can use the tool fully without ever requesting an explanation.

Swap is useful when you pasted the old and new version in the wrong boxes. Click swap and the comparison runs again with the correct order.

Use Previous and Next to move through changes when the result is long. The counter shows which change you are on. Clear when you are done so you can paste a new pair of texts without leftover content.