Why not word-level highlighting?

This version is line-oriented for speed—split paragraphs across lines if you need finer grain.

Whitespace sensitivity?

Blank lines and whitespace-only lines are skipped for the diff so structure maps to real sentences and paragraphs. Leading and trailing spaces on a non-empty line still count in line equality.

Dynamic pages differ nightly?

Fetch twice in a row can differ if ads rotate—compare static snapshots when possible.

The diff runs on the first 4,000 non-empty lines per side; beyond that, split the paste. Very large inputs can still slow the tab because the algorithm is browser-only.

Content & Writing

Live

Content Diff Tracker

Track how a page's content has changed across snapshots.

Old version

Fetch old

New version

Fetch new

Unchanged

Added lines

Removed lines

+14

Word delta

Line-by-line diff

Search engine optimization (SEO) is the practice of getting traffic from organic search results.

Good SEO requires technical work, content depth, and link building.

Search engine optimization is the practice of getting traffic from organic search results.

Good SEO requires technical work, content writing, and link building.

The most reliable wins come from fixing the boring fundamentals first.

Three concrete moves consistently grow traffic: refresh quarterly, internal-link weekly, audit CWV monthly.

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Start here · What this diff answers

See exactly which lines changed between two drafts or two live HTML snapshots.

Non-empty lines feed a longest-common-subsequence diff: unchanged lines stay muted, adds get green + rows, deletes get red strikethrough - rows. Summary tiles report Unchanged, Added lines, Removed lines, and Word delta (new minus old token count).

Fetch old / Fetch new run /api/fetch, then extractMainTextForDiff keeps paragraph-style line breaks (unlike the single-line collapse in extractMainText) so fetched pages still diff line by line. Noise like nav, footer, and cookie banners is stripped the same way.

When to use this tool

Algorithm update forensics
Store pre-update HTML in Old and post-refresh HTML in New.
Legal and compliance
Prove which disclaimers moved without reading two PDFs manually.
Freelancer QA
Validate that only agreed paragraphs changed between revision rounds.
Localization checks
Paste translated paragraphs beside the source to spot missing sections.

Examples

Walk through these with the form above — they are practice scenarios, not live data.

Word delta positive

Try this

Add two brand-new lines in the New textarea only.

What to look for

Added lines increments and Word delta turns positive.

Whole-line rewrite

Try this

Replace an existing line with a different sentence instead of editing words inline.

What to look for

Shows as one del and one add rather than inline word diff.

Short tutorial

Follow in order the first time you use the tool; later you can skip to the step you need.

Step 1 — Capture old state
Paste or Fetch old from the archived URL.
Step 2 — Capture new state
Use the current live URL or edited draft in New.
Step 3 — Read metrics
Totals tell you scope before scrolling the diff pane.
Step 4 — Walk the diff list
Scroll the monospace block; colors map to adds and deletes.
Step 5 — Decide next SEO actions
Large deletions may trigger thin content detector; similarity issues pair with content similarity checker.

More detail

New here? Skim Start here first, then run one Examples scenario in the form above.

Content Diff Tracker does one job: track how a page's content has changed across snapshots. It lives under Content & Writing on SEOToolkits, where the beginner idea is simple: Content SEO is the practice of making a page useful, clear, and complete enough to satisfy a searcher.

FAQ

Why not word-level highlighting?: This version is line-oriented for speed—split paragraphs across lines if you need finer grain.
Whitespace sensitivity?: Blank lines and whitespace-only lines are skipped for the diff so structure maps to real sentences and paragraphs. Leading and trailing spaces on a non-empty line still count in line equality.
Dynamic pages differ nightly?: Fetch twice in a row can differ if ads rotate—compare static snapshots when possible.
Max text size?: The diff runs on the first 4,000 non-empty lines per side; beyond that, split the paste. Very large inputs can still slow the tab because the algorithm is browser-only.