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Text Diff

See differences between two blocks of text at a glance.

Original Text

Paste the earlier version of your text.

Modified Text

Paste the updated version of your text.

Comparison options

Diff statistics

Similarity is unchanged lines divided by the larger input's line count; it is structural, not semantic.

Original lines
0
Modified lines
0
Unchanged lines
0
Added lines
0
Removed lines
0
Total changed lines
0
Line similarity
0%

What text diff does

Text Diff compares two editable blocks line by line. Unchanged lines stay aligned, while removed lines use a minus state and added lines use a plus state. Replacing a line appears as one removal and one addition so the exact text stays visible.

Side-by-side and unified views

Side-by-side view aligns the original and modified regions for visual review. Unified view shows one deterministic sequence that can be copied or downloaded, with space, minus, and plus prefixes for unchanged, removed, and added lines.

Matching rules and line endings

Ignore whitespace trims line edges and collapses repeated whitespace only while matching; Ignore case compares letters without case. Neither option changes displayed text. LF, CRLF, and CR are treated as equivalent separators. A final newline is a terminator, not a phantom empty line, while empty lines within the text remain meaningful.

Performance and privacy

The local LCS comparison first removes equal leading and trailing regions, then uses a bounded line matrix for the remaining region. Very large unmatched inputs are stopped with a browser-only warning instead of risking a freeze. Your text stays in your browser. Nothing you enter is uploaded or automatically saved.

Frequently asked questions

What is a unified diff?

It is a single list where unchanged lines start with a space, removed lines with -, and added lines with +.

What does Ignore whitespace do?

It trims line edges and treats repeated whitespace as one space for matching, without rewriting either input.

Does this compare character by character?

No. The primary comparison is line-based, which keeps later lines aligned when a line is inserted or removed.

Can I compare very large files?

Moderately large text is supported locally. Extremely large unmatched regions are safely limited because line LCS work grows with both line counts.

Can I copy the diff?

Yes. Copy Unified Diff and Download Diff export the same deterministic plain-text representation.

Does Unicode work?

Yes. Text is compared and displayed as entered, including Marathi, Hindi, emoji, accents, and combining characters.

Practical guide

When to use it

Use it to review changes between two versions of notes, generated output, configuration, or prose before sharing a patch.

Three steps

  1. Paste the original text and the modified text into their separate editors.
  2. Choose matching options only if differences in case or whitespace are irrelevant.
  3. Read the highlighted lines or copy the unified diff for a record.

Example and a common mistake

Compare two release notes to see a removed sentence and an added version number line by line.

This is a line-based comparison, so a single rewritten paragraph can appear as a removal plus an addition.

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