Canvases were meant to be the durable answer, but the answer still ends up buried under threads. Sidenote reads the canvas you ingested and cites the exact passage, so the durable doc actually answers.
For Slack Canvases
Ask your Slack canvas — and get the receipts.
Sidenote is a Chrome extension that turns a Slack canvas into something that answers. Ingest a canvas, ask a question, click a citation — Sidenote shows you the exact passage that proves the answer. Read-only, no admin install, nothing read until you ingest it.
Read-only · You choose which canvases to ingest · No admin install
Sidenote
Q3 Launch — Canvas
Owners: Priya (GTM), Marco (Eng), Dani (Docs).
Ship date: launch is locked for Thursday, with the marketing site going live at 9am UK.
Open risks: pricing copy is still pending legal sign-off, which could push the go-live; staging soak still running.
Sidenote · answer
The marketing site goes live at 9am UK on Thursday — 1 though one open risk could move it: pricing copy is still waiting on legal 2.
The problem
The canvas has the answer. The channel keeps burying it.
A Slack canvas is where a team writes things down to stop re-deciding them — the launch plan, the owners, the open risks. Then the channel moves on, the canvas scrolls out of view, and the same questions come back as threads anyway.
Sidenote doesn't replace your canvas. It teaches it to answer — in your browser, on the canvas you've ingested, with a citation you can verify in one click.
How it works
How Sidenote works on a Slack canvas.
STEP 01
Open a canvas, ingest it
Open the canvas and ingest it from the Sidenote sidebar — read-only, nothing for a Slack admin to install. If the canvas is in a channel side panel where the URL doesn't change, copy the link from its ••• menu and paste it into the Ingest card.
STEP 02
Ask the question you'd ask the channel
“What's the ship date?” “Who owns docs?” “What are the open risks?” Sidenote queries across every canvas you've ingested — not just the one in front of you.
STEP 03
Click a citation, see the passage
Every claim is grounded in a quoted chunk of the canvas. Click the chip and Sidenote shows you the exact passage it came from — no scrolling the channel to double-check.
Working across a set of related canvases? Bundle them into a Collection and query the whole set at once — citations name the source canvas.
Use cases
What teams ask a canvas — and how Sidenote answers.
“What's the launch plan in the #q3-launch canvas?”
Sidenote answers from the canvas you ingested and quotes the exact step — not whatever scrolled past in the channel three days ago.
“Who owns each workstream?”
Canvases collect the owners table, the timeline and the open questions in one place. Sidenote reads it and cites the row.
“What did we agree on in the kickoff canvas?”
It pulls the decision out of the canvas and points at the line where it was written down — not a half-remembered thread.
“What are the open risks before we ship?”
Sidenote surfaces the risks section of the canvas and quotes the item that applies, with nothing invented around it.
“What's the onboarding checklist for new folks?”
New hires query the team canvas directly instead of pinging a channel. The checklist answers, citation attached.
“Give me the TL;DR of this long canvas.”
A sprawling canvas becomes a short, cited summary — every claim links back to the passage it came from.
Read-only by design
It reads the canvases you ingest. Nothing else in Slack.
Sidenote reads a canvas only once you ingest it yourself — from the sidebar, or by pasting the canvas link when it's open in a channel side panel. There's no workspace-wide crawl of your channels, messages or files, and no copy of all of Slack sitting on someone else's server.
Access is read-only: Sidenote never posts, never edits the canvas, never touches anything you didn't hand it. If you didn't ingest it, Sidenote can't see it.
Your canvas content stays in your account.
Ingested canvases live behind row-level security in our UK (eu-west-2) Supabase region — no two accounts can read each other's chunks. Anthropic and Voyage AI both run with no-training defaults on the API tiers we use; we never fine-tune models on user content.
Compared
Sidenote vs the usual ways to read a canvas.
A canvas is the durable doc — but reading it back still falls to scrolling or copy-paste. Sidenote is the cross-source reader that answers from the canvas and proves it.
Copy-paste loses the structure and the source. Sidenote ingests the canvas in place, checks every answer against the retrieved passages, and links each claim back to where it came from — so you can trust it.
FAQ
Common questions about Sidenote for Slack canvases.
Open the canvas, then ingest it from the Sidenote sidebar. There's nothing for a Slack admin to install — Sidenote is a Chrome extension, and you ingest each canvas yourself, read-only. If the canvas is open in a channel side panel, where the page URL doesn't change, use the paste-the-link option instead (see below).
When a canvas opens in a channel's side panel, Slack doesn't change the page URL, so Sidenote can't detect it automatically. Use the paste-the-link option in the Ingest card: open the canvas's ••• menu, copy the link, and paste it in. Sidenote then reads that canvas like any other.
No. Sidenote reads the canvases you ingest, not all of Slack. It's per-canvas and opt-in: a canvas is only read once you ingest it yourself. There's no background crawl of your channels, messages, or files, and no global content store. Use Collections to bundle the canvases you do ingest into a set you can query in one go.
Yes. Sidenote reads a canvas you ingest and never writes back to it — it doesn't post messages, edit the canvas, or touch anything else in Slack. It answers your questions about the canvases you've chosen to ingest, and nothing more.
No. Anthropic (the model provider) and Voyage AI (the embedding provider) both run with no-training defaults on the API tiers Sidenote uses, and Sidenote never fine-tunes models on user content. Your canvas content is used only to answer your own questions, stored in a UK (eu-west-2) region with row-level security isolating every account.
Yes. Every answer is grounded in a quoted chunk of the canvas you ingested, and each citation chip names the source canvas and the passage it came from — so you can verify the answer instead of trusting it blind.
Try it on a canvas
Make your Slack canvas answer back.
Add Sidenote to Chrome, ingest a canvas read-only, and ask the question your channel keeps re-asking. No admin install. Free tier forever, 7-day Pro trial — no card required.
Read-only · You choose which canvases to ingest