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Productivity · head to head

Capacities vs Spark Mail

Capacities logo

Capacities

Productivity

A studio for your mind with object-based notes

From
Free
Rated
-
Full reviewWebsite
Spark Mail logo

Spark Mail

Productivity

AI-assisted email client from Readdle with a Smart Inbox and team collaboration features

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Capacities pro plan pricing not prominently displayed on website; Spark Mail several sync features route mail metadata and, for some features, credentials through Readdle servers, which is a materially different trust model from a local-only IMAP client.
  • They diverge on capability: Capacities covers Object-based notes, Spark Mail covers Smart Inbox.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Capacities and Spark Mail actually diverge.

Attributes where Capacities and Spark Mail differ
AttributeCapacitiesSpark Mail
Pricing modelUnknownPer user per month
PlatformsWeb, macOS, Windows, Linux, iOS, AndroidmacOS, Windows, iOS, Android, Web
Founded2020Unknown

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Productivity).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Capacities

  • Object-based notes
  • Daily notes
  • Properties and relations
  • Graph view
  • AI assistant
  • Readwise
  • Web clipper
  • GDPR

Only in Spark Mail

  • Smart Inbox
  • AI Copilot
  • AI Summaries
  • Team collaboration
  • Send later and snooze
  • Multi-account unified inbox

What people use each for

The jobs each tool is most often brought in to do.

Capacities

  • Productivitynot Spark Mail
  • Collaborationnot Spark Mail
  • Task managementnot Spark Mail
  • Organizationnot Spark Mail

Spark Mail

  • A freelancer juggling Gmail and Outlook accounts who wants one AI-assisted inboxnot Capacities
  • A small support team sharing a single inbox with internal notes before replyingnot Capacities
  • Someone who wants drafts and summaries generated without switching to a new mail hostnot Capacities
  • A user who wants notification triage without writing their own filtersnot Capacities

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Capacities

  • Pro plan pricing not prominently displayed on website
  • Smaller community and ecosystem compared to Notion or Obsidian
  • Limited third-party integration marketplace

Spark Mail

  • Several sync features route mail metadata and, for some features, credentials through Readdle servers, which is a materially different trust model from a local-only IMAP client.
  • It is a client over accounts you still pay for elsewhere, so the total cost is Spark plus whatever Gmail, Outlook or Fastmail plan you already hold.
  • The free tier lacks AI Copilot and summaries, so the features it is best known for sit behind the paid plan.
  • Team features are basic next to dedicated shared-inbox tools like Front or Help Scout, so a support team scaling past a few agents will likely outgrow it.
  • Windows and Android versions have historically lagged the macOS and iOS apps in feature parity.

Pricing, plan by plan

Capacities

Free
  • FreeFree
    • Unlimited spaces and objects
    • Device synchronization
    • Unlimited custom object types
  • Pro$10/month
    • Everything in Free
    • Unlimited notes
    • Advanced graph views
  • Believer$149.88/year
    • Everything in Pro
    • Beta access to new features

Spark Mail

Free
  • BasicFree
    • Unlimited accounts
    • Smart Inbox
    • Basic send later
  • Premium$7.99/month
    • AI Copilot and summaries
    • Unlimited snooze and send later
    • Priority support
  • Premium Teams$10/month
    • Shared inboxes
    • Delegation and internal comments
    • Admin controls

Which should you pick?

Choose Capacities if

  • You need object-based notes.
  • You want to start without paying.
  • You work on Web, macOS, Windows, Linux, iOS, Android.
  • You also want daily notes.
Capacities review

Choose Spark Mail if

  • You need smart inbox.
  • You want to start without paying.
  • You work on macOS, Windows, iOS, Android, Web.
  • You also want ai copilot.
Spark Mail review

Questions people ask

Is Capacities or Spark Mail better?
Neither clearly leads. Capacities starts at Free and Spark Mail at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Capacities or Spark Mail?
Capacities starts at Free and Spark Mail at Free.
Does Capacities or Spark Mail run on more platforms?
Capacities runs on Web, macOS, Windows, Linux, iOS, Android. Spark Mail runs on macOS, Windows, iOS, Android, Web.
Can I use Capacities for free?
Both have a free tier, so you can try either at no cost before committing.
What is Capacities best used for?
Capacities is most often used for productivity, collaboration, task management, organization. Of those, productivity and collaboration are not what Spark Mail is typically brought in for.
What can Capacities do that Spark Mail cannot?
Capacities covers Object-based notes, Daily notes, Properties and relations, Graph view. Spark Mail covers Smart Inbox, AI Copilot, AI Summaries, Team collaboration.

Answered from the vendors’ own pages

Capacities: What platforms does Capacities support?

Capacities is available on Web, Desktop (macOS, Windows, Linux), and Mobile (iOS, Android), allowing seamless work across devices.

Source
Spark Mail: Does Spark host my email?

No. It is a client that connects to Gmail, Outlook, iCloud or any IMAP account; you still need a mail host.

Capacities: Does Capacities have a free plan?

Yes, Capacities offers a free plan with unlimited spaces, objects, and blocks, device synchronization, unlimited custom object types, and 5GB media uploads total.

Source
Spark Mail: Does Spark store my email credentials on its servers?

For some features, including cross-device snooze and send-later sync, yes. It is part of how those features stay consistent across devices.

Capacities: What AI features does Capacities include?

Capacities includes an AI Assistant available on Pro and higher plans for brainstorming, summarization, and contextual Q&A about your notes.

Source
Spark Mail: Is there a one-time purchase option?

No, Spark is subscription only for individuals and teams; the base client is free but AI and unlimited scheduling need Premium.

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