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Productivity · head to head

Fastmail vs Obsidian

Fastmail logo

Fastmail

Productivity

Paid email hosting with custom domains, calendar and contacts, run without ad-based revenue

From
$3/month
Rated
-
Full reviewWebsite
Obsidian logo

Obsidian

Research

A powerful knowledge base on top of a local folder of plain text Markdown files

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only Obsidian has a free tier, so it costs nothing to try first.
  • Each has a real cost: Fastmail it does not provide end-to-end encryption by default, so users specifically wanting zero-knowledge mail should compare it against Proton Mail or Tuta rather than assume parity.; Obsidian sync is a paid add-on at $4 per month billed annually rather than part of the app
  • They diverge on capability: Fastmail covers Custom domain hosting, Obsidian covers Bidirectional linking.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Fastmail and Obsidian actually diverge.

Attributes where Fastmail and Obsidian differ
AttributeFastmailObsidian
Starting price$3/monthFree
Pricing modelPer user per monthUnknown
Free tierNoYes
PlatformsWeb, iOS, Android, macOS, WindowsWeb, Windows, macOS, Linux, iOS, Android
CategoryProductivityResearch
FoundedUnknown2020

Identical on both: user rating (Not yet rated).

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 Fastmail

  • Custom domain hosting
  • Masked email
  • Unlimited aliases
  • Integrated calendar and contacts
  • Migration tools
  • JMAP support

Only in Obsidian

  • Bidirectional linking
  • Graph view visualization
  • Markdown support
  • Local file storage
  • Plugin ecosystem
  • Custom CSS themes
  • Templates
  • Search and tags

What people use each for

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

Fastmail

  • Someone who wants their email address tied to a domain they own rather than a free provider they do notnot Obsidian
  • A small business wanting hosted mail on its own domain without running mail server infrastructurenot Obsidian
  • A person leaving Gmail specifically to stop an ad-funded provider processing their mailnot Obsidian
  • A household migrating several accounts to one paid provider with shared billingnot Obsidian

Obsidian

  • Local-first markdown note taking with no account requirednot Fastmail
  • Linking notes into a personal knowledge graphnot Fastmail
  • Syncing a vault across devices with end-to-end encryption on the paid add-onnot Fastmail
  • Publishing a public site from a vaultnot Fastmail
  • Extending the editor with community pluginsnot Fastmail

Where each one falls short

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

Fastmail

  • It does not provide end-to-end encryption by default, so users specifically wanting zero-knowledge mail should compare it against Proton Mail or Tuta rather than assume parity.
  • Moving to Fastmail is a real migration with DNS changes for a custom domain, unlike installing a client such as Spark or Bluemail over an existing account.
  • There is no free tier at all, so a user just wanting to try it commits to a paid trial rather than a permanently free option.
  • Storage limits on the entry Basic plan are modest next to the free allowance Gmail gives, and heavy attachment users will need Standard or above.
  • Being based in Australia means it falls under Australian data access law, which some privacy-focused buyers weigh differently from Swiss or German jurisdictions used by Proton Mail and Tuta.

Obsidian

  • Sync is a paid add-on at $4 per month billed annually rather than part of the app
  • Publishing to the web is a further $8 per month per site
  • Commercial use asks for a $50 per user per year licence, though the vendor states it is not required
  • Collaboration is limited compared with a hosted notes tool, since the vault is local files first

Pricing, plan by plan

Fastmail

$3/month
  • Basic$3/month
    • 6GB storage
    • No custom domain support
    • Core mail, calendar and contacts
  • Standard$5/month
    • 60GB storage
    • Custom domain support
    • Masked email and aliases
  • Professional$9/month
    • 150GB storage
    • Multiple custom domains
    • Priority support

Obsidian

Free
  • Obsidian Sync$4/month
    • Sync notes across devices
  • Obsidian Publish$8/month
    • Turn notes into a website

Which should you pick?

Choose Fastmail if

  • You need custom domain hosting.
  • You work on Web, iOS, Android, macOS, Windows.
  • You also want masked email.
Fastmail review

Choose Obsidian if

  • You need bidirectional linking.
  • You want to start without paying.
  • You work on Web, Windows, macOS, Linux, iOS, Android.
  • You also want graph view visualization.
Obsidian review

Questions people ask

Is Fastmail or Obsidian better?
Neither clearly leads. Fastmail starts at $3/month and Obsidian at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Fastmail or Obsidian?
Obsidian has a free tier; the other does not. Paid plans start at $3/month for Fastmail and Free for Obsidian.
Does Fastmail or Obsidian run on more platforms?
Fastmail runs on Web, iOS, Android, macOS, Windows. Obsidian runs on Web, Windows, macOS, Linux, iOS, Android.
Can I use Obsidian for free?
Yes. Obsidian has a free tier, so you can try it without paying. Fastmail starts at $3/month.
What is Fastmail best used for?
Fastmail is most often used for someone who wants their email address tied to a domain they own rather than a free provider they do not, a small business wanting hosted mail on its own domain without running mail server infrastructure, a person leaving gmail specifically to stop an ad-funded provider processing their mail, a household migrating several accounts to one paid provider with shared billing. Of those, someone who wants their email address tied to a domain they own rather than a free provider they do not and a small business wanting hosted mail on its own domain without running mail server infrastructure are not what Obsidian is typically brought in for.
What can Fastmail do that Obsidian cannot?
Fastmail covers Custom domain hosting, Masked email, Unlimited aliases, Integrated calendar and contacts. Obsidian covers Bidirectional linking, Graph view visualization, Markdown support, Local file storage.

Answered from the vendors’ own pages

Fastmail: Is Fastmail a client like Spark, or does it host my email?

It hosts the mailbox itself; there is no separate provider underneath it the way Spark sits over Gmail.

Obsidian: Is Obsidian free?

Yes. The core Obsidian application is 100% free for personal and commercial use with no limitations. You can use unlimited vaults and every core feature without payment.

Source
Fastmail: Does Fastmail offer end-to-end encryption?

Not by default in the way Proton Mail or Tuta do; its privacy position rests on being subscription-funded rather than ad-funded.

Obsidian: What file format does Obsidian use?

Obsidian stores every note as a plain Markdown file. Because it uses standard Markdown instead of a proprietary format, your notes remain portable and can be edited with many other Markdown editors.

Source
Fastmail: Can I use my own domain?

Yes, from the Standard plan up, with full alias and masked email support.

Obsidian: Can I collaborate with others in Obsidian?

The core application does not include built-in team collaboration features. However, Obsidian offers optional add-ons and can be used with version control systems or cloud storage for collaboration.

Source
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