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Cybersecurity · head to head

Proton Mail vs Sardine

Proton Mail logo

Proton Mail

Cybersecurity

Secure email that protects your privacy

From
Free
Rated
-
Full reviewWebsite
Sardine logo

Sardine

Cybersecurity

Device intelligence and behaviour biometrics for fraud and compliance

From
On request
Rated
-
Full reviewWebsite

The short version

  • Only Proton Mail has a free tier, so it costs nothing to try first.
  • Each has a real cost: Proton Mail paid plan pricing not displayed on vendor site; Sardine signal quality depends on the SDK being embedded in your own web and mobile clients, so fraud improvements become dependent on your app release cycle and any coverage gap is a blind spot.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Proton Mail and Sardine actually diverge.

Attributes where Proton Mail and Sardine differ
AttributeProton MailSardine
Starting priceFreeOn request
Pricing modelfreemiumquote
Free tierYesNo
PlatformsWebWeb, iOS, Android

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

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 Proton Mail

Nothing recorded that Sardine does not also cover.

Only in Sardine

  • Device intelligence
  • Behaviour biometrics
  • Scam detection
  • Onboarding risk scoring
  • AML transaction monitoring
  • Dispute and chargeback handling
  • Rules editor

What people use each for

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

Proton Mail

  • Encrypted email communicationnot Sardine
  • Privacy-focused email servicenot Sardine
  • Family email protectionnot Sardine

Sardine

  • A neobank losing money to authorised push payment scams where the customer genuinely approved the transfernot Proton Mail
  • A crypto exchange trying to detect accounts being operated by remote access rather than by their ownernot Proton Mail
  • A fintech seeing synthetic identity signups that pass document verification but share device characteristicsnot Proton Mail
  • A lender wanting first party fraud signals at application time that a credit bureau file does not containnot Proton Mail

Where each one falls short

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

Proton Mail

  • Paid plan pricing not displayed on vendor site
  • Free tier limited to 1 GB storage
  • Free tier limited to single email address

Sardine

  • Signal quality depends on the SDK being embedded in your own web and mobile clients, so fraud improvements become dependent on your app release cycle and any coverage gap is a blind spot.
  • Behavioural and device telemetry collection needs a documented lawful basis under GDPR, and EU privacy reviews frequently delay rollouts that were scoped as engineering work.
  • Pricing is per session or per active user, so a consumer product with many low value sessions pays in proportion to traffic rather than to fraud exposure.
  • As a younger private company it lacks the enforcement-tested audit history that a bank examiner expects, which makes it a harder sell inside a regulated bank than inside a fintech.
  • It is strongest on session-time signals and weaker as a system of record for long horizon AML typologies, so larger institutions end up running it alongside a traditional monitoring platform rather than instead of one.

Pricing, plan by plan

Proton Mail

Free

No published plan breakdown. See the Proton Mail review.

Sardine

On request
  • Sardine$undefined/year
    • Priced per user session or per monthly active user
    • Annual contract with volume commitment
    • SDK for web, iOS and Android

Which should you pick?

Choose Proton Mail if

  • You want to start without paying.
Proton Mail review

Choose Sardine if

  • You need device intelligence.
  • You work on Web, iOS, Android.
  • You also want behaviour biometrics.
Sardine review

Questions people ask

Is Proton Mail or Sardine better?
Neither clearly leads. Proton Mail starts at Free and Sardine at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Proton Mail or Sardine?
Proton Mail has a free tier; the other does not. Paid plans start at Free for Proton Mail and On request for Sardine.
Does Proton Mail or Sardine run on more platforms?
Proton Mail runs on Web. Sardine runs on Web, iOS, Android.
Can I use Proton Mail for free?
Yes. Proton Mail has a free tier, so you can try it without paying. Sardine starts at On request.
What is Proton Mail best used for?
Proton Mail is most often used for encrypted email communication, privacy-focused email service, family email protection. Of those, encrypted email communication and privacy-focused email service are not what Sardine is typically brought in for.
What can Proton Mail do that Sardine cannot?
Sardine covers Device intelligence, Behaviour biometrics, Scam detection, Onboarding risk scoring.

Answered from the vendors’ own pages

Proton Mail: Is there a free version of Proton Mail?

Yes, Proton Mail offers a free plan with 1 GB storage, 1 encrypted email address, and basic features like folders, labels, and filters.

Source
Sardine: Does Sardine do document verification?

It focuses on device, behavioural and transaction signals, and integrates identity verification providers rather than being one. Treat it as complementary to a KYC vendor.

Proton Mail: What does the Mail Plus plan include?

Mail Plus includes 15 GB storage, 10 encrypted email addresses, support for 1 custom domain, 10 hide-my-email aliases, priority support, and access to Proton Calendar.

Source
Sardine: What does it need from us to work?

An SDK in your web and mobile applications plus transaction feeds. Without the client side collector you lose the signals that differentiate it.

Proton Mail: What is included in Proton Unlimited?

Proton Unlimited provides 500 GB storage, 15 email addresses, 3 custom domains, unlimited hide-my-email aliases, access to Mail, Calendar, VPN, Drive, and Pass, plus dedicated support.

Source
Sardine: Is pricing published?

No. It is quoted, typically per session or per monthly active user with an annual volume commitment.

Proton Mail: Does Proton Mail offer a money-back guarantee?

Yes, Proton Mail provides a 30-day money-back guarantee for paid plans.

Source
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