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Developer Tools · head to head

Keil MDK vs Semperis

Keil MDK logo

Keil MDK

Developer Tools

Microcontroller Development Kit for Arm-based devices

From
Free
Free plan
Yes
Full reviewWebsite
Semperis logo

Semperis

Cybersecurity

Identity threat detection and Active Directory forest recovery for AD, Entra ID and Okta, from a privately held US vendor.

From
On request
Free plan
No
Full reviewWebsite

The short version

  • Only Keil MDK has a free tier, so it costs nothing to try first.
  • Each has a real cost: Keil MDK pricing for Essential and Professional subscriptions not disclosed on primary site; Semperis scope is limited to Active Directory, Entra ID and Okta, so an organisation whose critical identity lives elsewhere gets little from it, and the recovery value declines in direct proportion to how much has already moved off on-premises AD.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

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

Attributes where Keil MDK and Semperis differ
AttributeKeil MDKSemperis
Starting priceFreeOn request
Pricing modelfreemiumquote
Free tierYesNo
CategoryDeveloper ToolsCybersecurity

Identical on both: platforms (Web), 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 Keil MDK

Nothing recorded that Semperis does not also cover.

Only in Semperis

  • Active Directory Forest Recovery
  • Malware-free restore
  • Replication-stream monitoring
  • Automated rollback
  • Attack indicator scoring
  • Entra ID and Okta coverage
  • Purple Knight
  • Forest Druid

What people use each for

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

Keil MDK

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

Semperis

  • An organisation that cannot answer an auditor or insurer asking how long it would take to rebuild Active Directory after a destructive attacknot Keil MDK
  • Post-incident recovery where domain controllers are compromised and restoring from system-state backup would reintroduce the attacker's footholdnot Keil MDK
  • Continuous detection of privileged group changes and directory-level tampering that domain controller security logs missnot Keil MDK
  • Hybrid estates where AD, Entra ID and Okta all matter and no single tool currently shows changes across the threenot Keil MDK

Where each one falls short

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

Keil MDK

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

Semperis

  • Scope is limited to Active Directory, Entra ID and Okta, so an organisation whose critical identity lives elsewhere gets little from it, and the recovery value declines in direct proportion to how much has already moved off on-premises AD.
  • The licence buys tooling, not a proven runbook: forest recovery is only worth what your last rehearsal demonstrated, and a plan that has never been executed end to end in a lab is an untested assumption regardless of what was purchased.
  • It overlaps with backup and directory management products from Quest, Veeam, Commvault and others, so the buyer must argue internally why a dedicated product is needed alongside a backup contract that already claims to protect Active Directory.
  • Running Directory Services Protector well requires someone who understands AD internals, replication metadata and Tier 0 attack paths, and without that person the alerts on privileged changes are either ignored or auto-reverted in ways that break legitimate administration.
  • Licensing is driven by identity object counts, so directories carrying years of stale user accounts and service principals pay for objects that should have been deleted, and the cleanup project that would reduce the bill is the one nobody has time for.

Pricing, plan by plan

Keil MDK

Free

No published plan breakdown. See the Keil MDK review.

Semperis

On request

No published plan breakdown. See the Semperis review.

Which should you pick?

Choose Keil MDK if

  • You want to start without paying.
Keil MDK review

Choose Semperis if

  • You need active directory forest recovery.
  • You also want malware-free restore.
Semperis review

Questions people ask

Is Keil MDK or Semperis better?
Neither clearly leads. Keil MDK starts at Free and Semperis at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Keil MDK or Semperis?
Keil MDK has a free tier; the other does not. Paid plans start at Free for Keil MDK and On request for Semperis.
Does Keil MDK or Semperis run on more platforms?
Both run on Web, so platform support will not decide this one for you.
Can I use Keil MDK for free?
Yes. Keil MDK has a free tier, so you can try it without paying. Semperis starts at On request.
What is Keil MDK best used for?
Keil MDK is most often used for embedded software development, arm microcontroller programming, professional development environments. Of those, embedded software development and arm microcontroller programming are not what Semperis is typically brought in for.
What can Keil MDK do that Semperis cannot?
Semperis covers Active Directory Forest Recovery, Malware-free restore, Replication-stream monitoring, Automated rollback.

Answered from the vendors’ own pages

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
Semperis: Does this replace my backups?

No. It replaces the Active Directory recovery procedure specifically. You still need backups for everything else, and the point of Semperis is that a generic system-state backup of a domain controller is a poor way to recover a forest because it restores the operating system along with whatever compromised it.

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
Semperis: Is it useful if we are cloud-only on Entra ID?

Partly. Directory Services Protector covers Entra ID and Okta for change tracking and posture, but the forest recovery product, which is the strongest reason to buy, applies to on-premises Active Directory. A genuinely cloud-only organisation should weigh it against Microsoft's own tooling.

Semperis: Are Purple Knight and Forest Druid really free?

Yes, both are free downloads with no licence requirement, and they are widely used by organisations that are not Semperis customers. They are also, transparently, the top of the sales funnel.

Semperis: How long does forest recovery actually take?

The honest answer is whatever your rehearsal took. The vendor's case is hours instead of days, and automation genuinely removes most manual steps, but the number that matters for your board is the one from a test in your own environment.

Semperis: Does it require agents on domain controllers?

It collects directory changes from the AD replication stream, which is what lets it see changes that bypass the security log. Deployment details vary by product and version, so confirm the exact architecture against your domain controller change-control rules.

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