Picking a web highlighter by colour count is the wrong axis. The tools that matter differ on where your highlights go and whether they survive a device change — not on how many pens they offer. This comparison is a decision framework, not a ranking.

Dimensions that actually matter

Dimension	Why it decides everything
Browser coverage	Chrome / Edge / Firefox / Safari, plus mobile if you read on a phone
Sync & export	Highlights are useless trapped in one tab; the path to Obsidian / SiYuan / Logseq is the real feature
Local-first vs account	Privacy and lock-in vs automatic cross-device sync
Free tier	Highlighting is usually free; sync, clipping and API often are not
PDF support	Some cover web + PDF together; others are web-only

Comparison at a glance

Tool	Browsers	Sync / export	Stance	Notes
WuCai Highlight	Chrome, Edge, Firefox, Safari	Obsidian, SiYuan, Logseq, flomo, Workflowy	Account (cross-device)	Web pages only today; adds page notes (a note per URL, separate from text highlights)
Web Highlights	Major browsers	Notes app, some export	Account	One of the more feature-complete options
Glasp	Browser + social	Public profile / social layer	Account	Strong if you want a shared, social reading layer
LINER	Browser	AI-summary oriented	Account	Leans into AI research and summaries
PAGENOTE / 一页一记	Browser	Local-first	No account	Privacy-angled: data stays local
Cubox	Browser	Collect + annotate	Account	Clipboard / read-later meets annotation
Diigo	Browser	Bookmark + annotate	Account	Long-standing bookmark-and-annotate tool

Features and free tiers change. Treat the table as a starting map and confirm on each site before you commit.

How to choose, by what you value

• You live in Obsidian / your notes app. Prioritise the sync column. WuCai Highlight syncs highlights, annotations and page notes to Obsidian, SiYuan, Logseq, flomo and Workflowy — see the Obsidian sync guide.
• Privacy first, no account. A local-first tool (data stays in your browser) fits better than anything account-based.
• You read on many devices. An account-based tool that syncs automatically will save you more than a local-only one.
• You need web + PDF in one place. Filter explicitly for PDF support — not every tool covers it, and some web-focused tools (including WuCai) are web-only today.
• You want a note on the whole article, not a sentence. That is a page note, distinct from highlighting a quote.

Where WuCai fits

WuCai Highlight is a web annotation tool in the sense that matters: highlight and annotate any page, clip articles, and attach a page note to the URL. The differentiator is the sync path — highlights, annotations and page notes flow to Obsidian, SiYuan, Logseq, flomo and Workflowy, so reading becomes part of your knowledge base. It runs across Chrome, Edge, Firefox and Safari (see install); the current boundary is web pages only, not PDFs (full picture in the highlight docs).

FAQ

What should I compare when choosing a web highlighter? Browser coverage, where highlights sync and export to (Obsidian, SiYuan, Logseq, flomo), local-first vs account, the free tier, and PDF support. Colour count matters far less than the sync and export path.

Which web highlighters sync to Obsidian? Several. WuCai Highlight syncs highlights, annotations and page notes to Obsidian, SiYuan, Logseq, flomo and Workflowy.

Is a local-first highlighter better? Local-first is better if privacy and avoiding lock-in matter most; account-based is better if you read across devices and want automatic sync.

Do web highlighters work on PDFs? It varies. Some cover web and PDF together; others, including WuCai Highlight, currently focus on web pages only.

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Related: Page note vs highlight · What is a web annotation tool · Sync highlights to Obsidian