The story behind Sidenote.
Sidenote is an AI reading assistant that answers questions about the documents in your browser - and shows you exactly where every answer came from. It's built and run in the UK by one person who cares about getting the details right.
Useful AI you can actually check.
Most document AI is fluent, confident, and sometimes quietly wrong. That failure mode is worst exactly where reading matters most: runbooks, contracts, research, the wiki page your team actually runs on. A summary you can't verify isn't a summary - it's a rumor.
So Sidenote was built around the opposite instinct: every answer must cite the passage it came from, the server validates those citations against the document, and anything it can't ground is dropped. Click a citation and the page scrolls to the exact source. If the document doesn't answer your question, it says so.
That one idea now runs across the tools you already use - Confluence, Notion, SharePoint, Google Docs, PDFs and the web - one assistant that reads everything and cites everything. See how citations work or every source it reads.
No citation, no claim.
Three rules shape every feature Sidenote ships. They cost some fluency - and buy answers you can act on.
Cited, or dropped
Every claim must quote the passage it came from. The server checks each citation against the text actually retrieved from your document and drops what it can't prove - rather than inventing a footnote.
Allowed to say no
If the document doesn't answer your question, Sidenote says so. An honest “that isn't in here” beats a confident guess every time.
Built to be checked
Click any citation and the live page scrolls to the exact sentence and highlights it. You never have to take an answer on faith - checking is one click.
A solo, independent UK product.
Who builds it
Sidenote is designed, built and supported by Lewis Hadden, a solo developer in the United Kingdom, trading as Sidenote. No venture backing, no growth team: a focused product, shipped for Chrome and Firefox, and a real person reading every support email. That's deliberate - it keeps the incentives simple and the product honest.
Private by default
Your documents are never used to train AI models. Data is stored in a UK region (eu-west-2), encrypted at rest, and isolated per account. Connected accounts are read-only and per-document, and disconnecting one deletes its tokens immediately. The full detail is in the privacy policy and the security & compliance overview.
Questions, feedback, or just want to say hello? Email support@getsidenote.app.
Lewis Hadden, trading as Sidenote · 40 Viking Way, Whittlesey, PE7 1DY, United Kingdom
Stop digging. Start asking.
Add Sidenote to your browser, open any page in your wiki, and ask it the question you’ve been Slacking the team about.
7-day Pro trial · No card required · Free plan forever