Substack file embeds

substack.com · Storage · 1 record · JSON

Substack file embeds Storage

caveatinstitutionno cardR

substack.com · media · storage/substack-file-embeds · JSON · compare

Free tier	no stated total; 700 MB per PDF, XLSX/CBZ/CBR embeds supported unit MB; metered on unstated
Price	none stated
Per-object cap	not stated
Retention	not stated
Egress	free, CDN-served download links on substackcdn.com, no auth for public posts
Identity	institution derived from the record's prose, not from an identity field, and no signup was executed: p the embed; Substack has no delete-then-restore story. No API is the hard blocker — this is a 'if someone writes the Playwright wrapper' candidate 700 MB x unlimited posts x unlimit
Binding	none no constraint in the record binds at this scale; the record carries no limit of a kind the vocabulary names
Interface	unknown wrapper-only
Tooling	no public upload API — file embeds are drag-and-drop in the post editor or into email drafts; would need browser automation (Playwright) against the logged-in editor
Composes with	700 MB x unlimited posts x unlimited publications (each free to create). This is the largest per-file limit of any social platform checked here; 20 TiB = ~29,000 PDFs
Reliability	attachments live with the post; editing a post can drop the embed; Substack has no delete-then-restore story. No API is the hard blocker — this is a 'if someone writes the Playwright wrapper' candidate
Notes	no stated total; 700 MB per PDF, XLSX/CBZ/CBR embeds supported
Evidence rung	reported One page read moves it to documented.
Checked	2026-10-21 (inherited); stale on 2026-11-04

Evidence (2)

date	source	what it proved
2026-10-21	support.substack.com/hc/en-us/articles/4408381643156-How-can	'The file size limit for a PDF is 700 MB'
2026-10-21	on.substack.com/p/new-tools-paywall-embeds	'Writers can now embed PDFs, Excel spreadsheets (XLSX), and comics files (CBZ, CBR) into their posts'

Unknown or withheld values (6)

$.free_tier.notes process
$.interface interface-unknown
$.per_object_cap.notes not-extracted
$.per_object_cap.stated not-extracted
$.retention.notes not-extracted
$.retention.stated not-extracted

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