You finish an article, close the tab, and a week later you remember it said something important — but not what, and not where. A web annotation tool is the fix: it lets you mark up pages where you read them, so the insight survives the close button.

What a web annotation tool actually does

At minimum it lets you:

• Highlight sentences on any page, like marking a book.
• Annotate the highlight with a note — why it matters, what to do with it.
• Clip the article or the selection for later.
• Attach a page note — a sticky note for the whole URL, separate from any text you selected (see page note vs highlight).

The point is that the marks belong to the article, not to a screenshot you'll never open again.

Who it's for

• Researchers pulling claims out of ten sources at once.
• Students building a reading layer over lecture material and papers.
• Knowledge workers who read on the commute and write at the desk — the notes have to follow.
• Anyone tired of a bookmark folder that remembers links but not ideas.

How to choose one

Question	Why it matters
Which browsers?	Chrome / Edge / Firefox / Safari, plus mobile if you read on a phone
Does it sync?	Notes are useless if they die with the tab; account sync keeps them across devices
Where do notes go?	Syncing to Obsidian / Logseq / SiYuan turns reading into a knowledge base
Privacy & export	Local-first or easy export means your notes aren't locked in
Free vs paid	Free usually covers highlighting; sync and clipping often need a plan

How WuCai fits

WuCai Highlight is a web annotation tool in this sense: highlight and annotate any page, clip articles, and attach a page note to the URL. Highlights, annotations and page notes sync to Obsidian, SiYuan, Logseq and flomo, and it runs across Chrome, Edge, Firefox and Safari — see the highlight feature docs and install for your browser.

FAQ

What is a web annotation tool? A browser extension that lets you mark up web pages — highlight text, add notes, clip articles, and sometimes attach a note to the whole page — with the marks staying with the article.

Is web annotation the same as highlighting? Highlighting is one part of annotation. Annotation also covers notes on the highlight, clipping, and page-level notes.

Can web annotations sync to Obsidian? Some can. WuCai Highlight syncs highlights, annotations and page notes to Obsidian, SiYuan, Logseq and flomo.

Which browsers do web annotation tools support? The useful ones cover Chrome, Edge, Firefox and Safari; check mobile support if you read on a phone.

Are web annotation tools free? Most have a free tier for highlighting and basic notes; sync, colours, clipping and API usually sit behind a paid plan.

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Related: Page note vs highlight · Sync highlights to Obsidian · Highlight any web page