Copy-paste loses the page's structure and the source, and you can end up debugging which bits the model invented. Sidenote ingests the page in place, checks every answer against the retrieved passages, and links each claim back to where it came from.
For web pages & articles
AI to read any web page - with the receipts.
Sidenote is a browser extension (Chrome, Edge and Firefox) that summarizes and answers questions about whatever article you're reading. Ask a question, click a citation, and Sidenote scrolls the page to the exact passage that proves the answer. No copy-paste, no upload, nothing left to take on trust.
No upload · Reads the page you already have open
Sidenote
Long read · 4,000 words
The quiet economics of the attention machine
The feed isn't selling your attention to advertisers - it's renting it back to you one impression at a time. Everything that follows is a footnote to that one inversion. In the period the piece covers, the top 3% of accounts produced just over 80% of all paid reach.
Sidenotecited
What is the main argument?
The feed doesn't sell your attention to advertisers - it rents it back to you, impression by impression1. The economics bear it out: the top 3% of accounts drove over 80% of all paid reach2.
2 sources · cited
The problem
The article has the answer. Reading all of it is the cost.
Long reads, dense documentation and ten-tab research sessions all share the same tax: the thing you actually need is buried somewhere in the middle, and a chatbot summary you can't verify just moves the problem. Now you don't know which bits were invented.
Sidenote summarizes the page you're on and answers your questions in the browser, and every claim comes with a citation that scrolls you to the exact sentence, so you can check it in one click.
How it works
How Sidenote works on a web page.
STEP 01
Open the article, open the panel.
Sidenote rides in your browser's side panel. No upload and no copy-paste: it reads the page you already have open, including long features and documentation.
STEP 02
Summarize it, or just ask.
Ask for a TL;DR, the key takeaways, or a question about a specific claim. Sidenote answers from the page in front of you, grounded in the passages it actually retrieved.
STEP 03
Click a citation, see the passage.
Every claim is backed by a quoted chunk of the page. Click the chip and Sidenote scrolls to the exact passage and highlights it - verification in one click.
Want the one-line version of this? Sidenote summarizes any page in a click - and citations scroll you to the exact source.
Use cases
What readers ask a page - and how Sidenote answers.
“What's the TL;DR of this long read?”
A 4,000-word feature becomes a short, cited summary - every line links back to the paragraph on the page it came from.
“Does this article actually back that claim?”
Ask about a specific assertion and Sidenote quotes the sentence that supports it - or tells you the page never says it.
“Explain this paragraph like I'm new to it.”
Highlight a dense passage and ask for plain English. The explanation stays grounded in what the page actually says.
“What are the three key takeaways here?”
Sidenote pulls the main points from a sprawling post and cites each one back to its source line.
“Where on this page does it mention pricing?”
Ask, click the citation, and Sidenote scrolls you straight to the passage - no Ctrl-F guessing at the right keyword.
“Compare what these two articles say.”
Bundle the pages you've opened into a collection and ask across all of them. Citations name which article each point came from.
Grounded by design
It reads the page in front of you. Nothing else.
Sidenote reads what your browser already sees in the current tab - it doesn't crawl the wider web in the background and it doesn't bypass anything your browser can't access. A page is only ever read once you open it with the side panel active, and answers are checked against the passages on that page before they reach you.
Unsupported claims lose their citation before you see them.
If a sentence in an answer isn't backed by a passage on the page, Sidenote drops its citation server-side. Page content lives behind row-level security in our UK (eu-west-2) region; Anthropic and Voyage AI both run with no-training defaults on the API tiers we use, and we never fine-tune models on user content.
Compared
Sidenote vs the usual way of reading.
Most AI reading tools either lose the source or never had it. Sidenote keeps the page, keeps the structure, and keeps a click-through to the line every answer rests on.
A plain summary tells you what an article roughly says. Sidenote tells you exactly where it says it: every line of the summary is a citation that scrolls the page to the source. Reading several pages at once? Bundle them into a collection and ask across all of them at once.
FAQ
Common questions about Sidenote for web pages.
Try it on your next tab
Read anything in your browser. With citations.
Add Sidenote to your browser, open the article you're putting off, and ask for the TL;DR - then click a citation to check it on the page. Free tier forever, opt-in 7-day Pro trial, no card required.
No upload · Reads the page you already have open