What is the difference between unified and side-by-side diffs?

Side-by-side shows the old and new text in two columns. Unified shows a single combined view where additions and deletions appear inline. Side-by-side is great for scanning; unified is great for sharing.

When should I use line-based vs word-based diff?

Line-based diff is best for code and structured text. Word-based diff is better for prose because it highlights small edits inside lines.

Why do I see changes that look identical?

Some changes come from whitespace differences or line-ending differences (LF vs CRLF). If something looks identical, try switching diff mode or checking for extra spaces or blank lines.

Does this tool upload the text I paste?

No. This diff checker runs locally in your browser and does not send your content to a server.

Diff Checker: Compare Two Texts

Paste two versions of a document or code snippet, see exactly what changed, and download a simple diff. Everything runs in your browser, with no accounts or uploads.

Text you paste here never leaves your browser.

The diff is computed entirely on your device. You can safely compare drafts, emails, or snippets of code without sending them to a server.

Original

Modified

Diff results

Green highlights show additions, red highlights show removals, and plain text is unchanged.

Original with removals

Paste text above and start editing to see differences.

Modified with additions

Paste text above and start editing to see differences.

Legend

Green – added text
Red – removed text
Plain – unchanged text

Compare edits and revisions without heavy tooling

A diff checker highlights how one version of text differs from another. It is useful when reviewing edits to blog posts, checking email drafts, or comparing snippets of code before a commit. Instead of scanning line by line, you can see additions and deletions at a glance, with subtle color cues for what changed.

Use cases for a lightweight diff tool

Comparing versions of copy. Paste an earlier draft on the left and a new draft on the right to see what a collaborator changed.
Reviewing small code changes. Before committing, you can quickly compare two snippets to be sure nothing unexpected slipped in.
Tracking edits to support replies or emails. If you write a sensitive response, it can be helpful to check exactly what changed between versions.

Line‑based vs word‑based diffs

Line‑based diffs treat each line as a unit, which works well for code and structured text. Word‑based diffs zoom in further and highlight individual word changes inside a line. This tool lets you toggle between those modes so you can either see high‑level structure or fine‑grained edits, depending on what you are reviewing.

Examples you can try

A quick way to understand diffs is to paste a small before/after pair. For example, put this on the left:

Hello team, Please review the draft. Thanks, Pat

And this on the right:

Hello team, Please review the updated draft. Thanks, Pat

Word-based diff will highlight the single word change, while line-based diff will show which line changed.

Common edge cases: whitespace and line endings

If the diff looks noisy, the issue is often invisible whitespace: extra spaces, tabs, or different newlines. Some systems store text with Windows line endings (CRLF) while others use Unix line endings (LF). This tool will still compare the raw text, so those differences can appear as changes even when the visible text looks the same.

Client‑side privacy for sensitive content

Many diff services upload your text to a remote server. That may not be ideal if you are comparing contracts, internal docs, or private messages. This Diff Checker runs entirely in your browser; the algorithm runs locally and nothing is sent to LifeHackToolbox or any third party. You can paste sensitive text, compare versions, and close the tab knowing the content never left your device.

Part of a small toolkit of text utilities

This page is built to pair with other developer‑friendly tools such as the JSON Linter & Formatter , the Regex Playground, and the PDF Signature & Form Filler. Instead of a heavy IDE or complex version‑control UI, you get a simple browser tab that does one job cleanly.

Related tools

Diff checker FAQ

What is a diff checker used for?

A diff checker is used to see what changed between two versions of text: edits to a paragraph, changes to an email draft, or differences between two code snippets.

Which view should I use: unified or side-by-side?

Side-by-side is better when you want to scan two versions in parallel. Unified is better when you want a single artifact you can copy or download and share.

Why does it show changes for identical lines?

Usually it is whitespace: an extra space, a tab, or different line endings. If you suspect that, try a word-based diff and look closely for trailing spaces or blank lines.

Can I diff JSON specifically?

Yes, but formatting first can make diffs clearer. A common workflow is to pretty-print both JSON payloads in the JSON Linter & Formatter, then compare the formatted versions here.

Is the text uploaded anywhere?

No. This tool runs entirely in your browser and does not upload the text you paste.

For more structured programming workflows you might still want full version control, but for quick checks—diffing two small files, reviewing an email rewrite, or comparing JSON payloads—this tool is faster to open and easier to share with non‑technical teammates.