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Research · head to head

Greenphire vs Obsidian

Greenphire logo

Greenphire

Research

Clinical trial participant payments, reimbursement and travel, now part of Suvoda

From
On request
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: Greenphire the standalone greenphire.com site now redirects to Suvoda and the brands have been integrated, so buyers are contracting with a randomisation and supply vendor and should expect cross selling rather than an independent payments specialist.; Obsidian sync is a paid add-on at $4 per month billed annually rather than part of the app
  • They diverge on capability: Greenphire covers ClinCard, Obsidian covers Bidirectional linking.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Greenphire and Obsidian actually diverge.

Attributes where Greenphire and Obsidian differ
AttributeGreenphireObsidian
Starting priceOn requestFree
Pricing modelquoteUnknown
Free tierNoYes
PlatformsWeb, iOS, AndroidWeb, Windows, macOS, Linux, iOS, Android
FoundedUnknown2020

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

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 Greenphire

  • ClinCard
  • Direct to bank payment
  • Expense reimbursement
  • Travel and logistics
  • Site payments
  • Budgeting and benchmarking
  • Tax handling

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.

Greenphire

  • A global Phase III trial paying stipends across many countries where participants cannot practically be reimbursed by sponsor accounts payablenot Obsidian
  • A decentralised or hybrid trial where participants travel long distances and the sponsor funds flights and accommodationnot Obsidian
  • A trial in a population where slow reimbursement drives dropout and same day payment materially helps retentionnot Obsidian
  • A sponsor that wants site payment milestones and participant payments handled by one vendor rather than twonot Obsidian

Obsidian

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

Where each one falls short

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

Greenphire

  • The standalone greenphire.com site now redirects to Suvoda and the brands have been integrated, so buyers are contracting with a randomisation and supply vendor and should expect cross selling rather than an independent payments specialist.
  • Nothing is published on price, and the typical shape of a platform fee plus per participant and per transaction charges means the cost of a trial is not knowable until enrolment is known.
  • Payment method availability varies sharply by country, so a global protocol may end up with card payments in some regions and slow manual processes in others, which undermines the retention argument that justified the purchase.
  • Sites bear the administrative work of enrolling participants and triggering payments but are not the buyer, so adoption depends on the sponsor mandating it and site resistance is a real implementation risk.
  • Participant payments create tax reporting obligations that differ per jurisdiction, and the tooling helps but does not remove sponsor liability, so legal and finance review is required in every country the trial runs in.

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

Greenphire

On request
  • Greenphire Patient Payments$undefined/year
    • Priced per study through a sales process
    • Typically a platform fee plus per participant and per transaction charges
    • Funding of the payment float is separate from the software fee

Obsidian

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

Which should you pick?

Choose Greenphire if

  • You need clincard.
  • You work on Web, iOS, Android.
  • You also want direct to bank payment.
Greenphire 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 Greenphire or Obsidian better?
Neither clearly leads. Greenphire starts at On request and Obsidian at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Greenphire or Obsidian?
Obsidian has a free tier; the other does not. Paid plans start at On request for Greenphire and Free for Obsidian.
Does Greenphire or Obsidian run on more platforms?
Greenphire runs on Web, iOS, Android. 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. Greenphire starts at On request.
What is Greenphire best used for?
Greenphire is most often used for a global phase iii trial paying stipends across many countries where participants cannot practically be reimbursed by sponsor accounts payable, a decentralised or hybrid trial where participants travel long distances and the sponsor funds flights and accommodation, a trial in a population where slow reimbursement drives dropout and same day payment materially helps retention, a sponsor that wants site payment milestones and participant payments handled by one vendor rather than two. Of those, a global phase iii trial paying stipends across many countries where participants cannot practically be reimbursed by sponsor accounts payable and a decentralised or hybrid trial where participants travel long distances and the sponsor funds flights and accommodation are not what Obsidian is typically brought in for.
What can Greenphire do that Obsidian cannot?
Greenphire covers ClinCard, Direct to bank payment, Expense reimbursement, Travel and logistics. Obsidian covers Bidirectional linking, Graph view visualization, Markdown support, Local file storage.

Answered from the vendors’ own pages

Greenphire: Is Greenphire still sold?

Yes, as Greenphire Patient Payments on the Suvoda platform. The independent website and social presence have been consolidated into Suvoda.

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
Greenphire: What is ClinCard?

The reloadable debit card Greenphire issues to participants. Greenphire Patient Payments was formerly known as ClinCard.

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
Greenphire: Does it publish pricing?

No. Pricing is per study and quoted through sales, and funding the payments themselves is separate from the software fee.

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
Greenphire: Can it pay participants outside the United States?

Yes, in more than thirty currencies, but the available payment method depends on the country.

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