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Cybersecurity · head to head

Clerk vs Keil MDK

Clerk logo

Clerk

Cybersecurity

Drop-in user authentication and management for developers

From
Free
Free plan
Yes
Full reviewWebsite
Keil MDK logo

Keil MDK

Developer Tools

Microcontroller Development Kit for Arm-based devices

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: Clerk pricing scales with monthly retained users, which can grow expensive quickly for consumer apps with large user bases.; Keil MDK pricing for Essential and Professional subscriptions not disclosed on primary site
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which Clerk and Keil MDK actually diverge.

Attributes where Clerk and Keil MDK differ
AttributeClerkKeil MDK
Platformsweb, ios, android, apiWeb
CategoryCybersecurityDeveloper Tools

Identical on both: starting price (Free), pricing model (freemium), free tier (Yes), 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 Clerk

  • Prebuilt UI components
  • Organization management
  • Multi-factor authentication
  • Social sign-on
  • Billing
  • Enterprise connections

Only in Keil MDK

Nothing recorded that Clerk does not also cover.

What people use each for

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

Clerk

  • Adding sign-in and user profiles to a web or mobile app quicklynot Keil MDK
  • B2B SaaS apps needing organizations and role-based accessnot Keil MDK
  • Startups wanting prebuilt UI instead of building auth in-housenot Keil MDK
  • Apps needing MFA and fraud detection out of the boxnot Keil MDK

Keil MDK

  • Embedded software developmentnot Clerk
  • ARM microcontroller programmingnot Clerk
  • Professional development environmentsnot Clerk

Where each one falls short

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

Clerk

  • Pricing scales with monthly retained users, which can grow expensive quickly for consumer apps with large user bases.
  • Enterprise SSO connections beyond the first are billed as add-ons, adding cost for larger organizations.
  • The Business tier's extra dashboard seats cost $20/month each, which adds up for larger teams.
  • Enterprise-tier features like the 99.99% uptime SLA require annual contracts rather than flexible monthly billing.

Keil MDK

  • Pricing for Essential and Professional subscriptions not disclosed on primary site
  • Customers must contact Arm Developer Tools store for subscription rates

Pricing, plan by plan

Clerk

Free
  • HobbyFree
    • 50,000 MRU limit per app
    • Up to 3 dashboard seats
    • Unlimited applications
  • Pro$25/month
    • 50,000 MRUs included, $0.02/MRU overage
    • Up to 3 dashboard seats
    • 1 Enterprise Connection included
  • Business$300/month
    • 50,000 MRUs included with volume pricing
    • 10 dashboard seats included
    • SOC2 report and priority support
  • Enterprise$undefined/month
    • Custom pricing, annual billing
    • 99.99% uptime SLA
    • HIPAA available, dedicated Slack channel

Keil MDK

Free

No published plan breakdown. See the Keil MDK review.

Which should you pick?

Choose Clerk if

  • You need prebuilt ui components.
  • You want to start without paying.
  • You work on web, ios, android, api.
  • You also want organization management.
Clerk review

Choose Keil MDK if

  • You want to start without paying.
Keil MDK review

Questions people ask

Is Clerk or Keil MDK better?
Neither clearly leads. Clerk starts at Free and Keil MDK at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Clerk or Keil MDK?
Clerk starts at Free and Keil MDK at Free.
Does Clerk or Keil MDK run on more platforms?
Clerk runs on web, ios, android, api. Keil MDK runs on Web.
Can I use Clerk for free?
Both have a free tier, so you can try either at no cost before committing.
What is Clerk best used for?
Clerk is most often used for adding sign-in and user profiles to a web or mobile app quickly, b2b saas apps needing organizations and role-based access, startups wanting prebuilt ui instead of building auth in-house, apps needing mfa and fraud detection out of the box. Of those, adding sign-in and user profiles to a web or mobile app quickly and b2b saas apps needing organizations and role-based access are not what Keil MDK is typically brought in for.
What can Clerk do that Keil MDK cannot?
Clerk covers Prebuilt UI components, Organization management, Multi-factor authentication, Social sign-on.

Answered from the vendors’ own pages

Clerk: What does Clerk cost?

Clerk's Hobby plan is free with a 50,000 MRU limit; Pro is $25/month ($20/month billed annually), Business is $300/month ($250 annually), and Enterprise uses custom annual pricing.

Source
Keil MDK: Does Keil MDK have a free version?

Yes, Keil MDK Community Edition is free for non-commercial projects. Essential and Professional editions are available as monthly or annual subscriptions.

Source
Clerk: Is there a free plan and what are its limits?

Yes, the Hobby plan is free with a 50,000 monthly retained user (MRU) limit per app, up to 3 dashboard seats, and unlimited applications, with no credit card required.

Source
Keil MDK: How much do Keil MDK paid editions cost?

Specific pricing for Essential and Professional editions is not published on the main site. Rates are available from the Arm Developer Tools store or by contacting Arm sales.

Source
Clerk: How is usage metered?

Clerk meters by monthly retained users (MRUs) — users who return to the app at least a day after signing up — with overage billed at $0.02 per MRU beyond the included 50,000 on paid plans.

Source
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