Private developer tools

Text Diff Checker

Compare original and revised text line by line, inspect highlighted edits, and export a unified diff without uploading either version.

Choose comparison options, then compare.

How to use it

Get a reliable result

  1. Paste the earlier version into Original text and the newer version into Revised text.
  2. Choose whether case or whitespace differences should be ignored and whether paired lines should highlight changed words.
  3. Compare the versions, inspect the side-by-side or unified view, then copy or download the diff.

Useful for

Common workflows

  • Review edits between document drafts
  • Compare configuration or source-code snippets
  • Create a portable record of changed lines

Examples

What to expect

Revised sentence
Input
Original: Runs in your browser. Revised: Runs locally in your browser.
Output
One changed line with locally highlighted as an addition
Whitespace-only edit
Input
Two lines differing only in repeated spaces
Output
No reported change when Ignore whitespace is enabled

Know before you start

Important limitations

  • Changed lines are paired by their position inside each adjacent delete-and-insert block; heavily reordered passages can appear as separate removals and additions.
  • The exported unified-style diff omits hunk coordinates and is not guaranteed to be directly applicable by patch or source-control software.
  • Ignore whitespace trims lines and collapses consecutive whitespace for comparison, which can conceal meaningful indentation changes.
  • Word highlighting is computed only for paired changed lines and does not perform semantic, moved-block, grammar, or authorship analysis.
  • Each side is limited to 500,000 characters and 5,000 lines, and exceptionally dissimilar input may be rejected to protect browser responsiveness.

Keep exploring

More developer tools

JSON FormatterValidate, beautify, sort, inspect, minify, copy, and download JSON locally.Open JSON Formatter →JSON ↔ CSV ConverterConvert JSON object arrays to quoted CSV or parse CSV records into formatted JSON.Open JSON ↔ CSV Converter →Word CounterCount words, characters, sentences, paragraphs, lines, and estimated reading time.Open Word Counter →How to Count Words AccuratelyLearn why word counts differ across editors and how punctuation, compounds, numbers, scripts, and counting rules affect the result.Read guide →

Common questions

Text Diff Checker FAQ

What do changed, added, and removed mean?

A changed row pairs a removed line with a nearby added line. Added and removed counts represent unpaired lines that exist on only one side.

Does Ignore whitespace preserve the displayed text?

Yes. It trims and collapses spacing only while deciding whether lines match; the original characters remain visible in the editors and result.

Is this a patch file for source control?

The download uses familiar --- and +++ headers with line prefixes, but it omits hunk coordinates and is intended for review rather than direct application by patch software.

Are either text version or the diff uploaded?

No. Comparison, highlighting, copying, and file creation happen locally in the current browser tab.

Browser-local

Processed on your device

Original text, revised text, and comparison results stay in this browser and are never uploaded or stored.

How this processing works

The tool reads and processes this input in your browser. Tool Packer's application server does not receive the input or generated result.

Read the full privacy explanation