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Card 816 of 9932026-09-21 issue

Observed arrival · 2026-09-21

Subcanvas, the whiteboard that keeps opening

subcanvas.app Visit website
Editorial interest 84/100 Selection signal · not a rating of the site

A nested whiteboard for diagrams, notes, and repository maps, where boxes and arrows can each contain deeper material.

Landing page captured for the 2026-09-21 issue.
For
Developers mapping systems and teams organizing nested plans
Worth noticing
An optional .subcanvas file turns declared repository connections into arrows with descriptions.

Field notes

The interface models hierarchy directly: a folder, story act, course week, or system component can open into another sheet, with a tab trail leading back outward. For repository work, the importer uses folder paths and README files, while an optional .subcanvas file declares relationships such as a payments service connecting to a ledger over gRPC. The site also publishes an AGPL-3.0 self-hosting option.

Observed signals

Read the marks

Editorial observations of this landing page, not a rating.

OpenPublic substance visible
$PaidCommerce or pricing visible
PrettyNotable craft visible
ProPolished or operationally mature
NicheUnusually specific use
ƒJavaScriptBrowser-side code central

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subcanvas.app

Landing page observed 2026-09-21. The live site may have changed.