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Developer Tools · head to head

Keil MDK vs Preact

Keil MDK logo

Keil MDK

Developer Tools

Microcontroller Development Kit for Arm-based devices

From
Free
Free plan
Yes
Full reviewWebsite
Preact logo

Preact

Web Development

3kB alternative to React with the same modern API

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: Keil MDK pricing for Essential and Professional subscriptions not disclosed on primary site; Preact compatibility through preact/compat is good but not total, and some React libraries break in ways that are hard to diagnose
  • Prices and features above were last checked on 29 August 2026.

Where they differ

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

Attributes where Keil MDK and Preact differ
AttributeKeil MDKPreact
Pricing modelfreemiumOpen source, no licence fee
CategoryDeveloper ToolsWeb Development

Identical on both: starting price (Free), free tier (Yes), 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 Preact does not also cover.

Only in Preact

  • 3kB runtime
  • preact/compat
  • Same modern API
  • Fast rendering

What people use each for

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

Keil MDK

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

Preact

  • Embedded widgets that load inside someone else’s page and must stay smallnot Keil MDK
  • Marketing and content sites where JavaScript payload affects Core Web Vitalsnot Keil MDK
  • Applications targeting low-bandwidth or low-powered devicesnot 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

Preact

  • Compatibility through preact/compat is good but not total, and some React libraries break in ways that are hard to diagnose
  • Behavioural differences from React exist in edge cases, particularly around event handling
  • A much smaller community, so unusual problems have fewer existing answers than React

Pricing, plan by plan

Keil MDK

Free

No published plan breakdown. See the Keil MDK review.

Preact

Free
  • PreactFree
    • Full library
    • Commercial use permitted
    • No usage limits

Which should you pick?

Choose Keil MDK if

  • You want to start without paying.
Keil MDK review

Choose Preact if

  • You need 3kb runtime.
  • You want to start without paying.
  • You also want preact/compat.
Preact review

Questions people ask

Is Keil MDK or Preact better?
Neither clearly leads. Keil MDK starts at Free and Preact at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Keil MDK or Preact?
Keil MDK starts at Free and Preact at Free.
Does Keil MDK or Preact 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?
Both have a free tier, so you can try either at no cost before committing.
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 Preact is typically brought in for.
What can Keil MDK do that Preact cannot?
Preact covers 3kB runtime, preact/compat, Same modern API, Fast rendering.

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
Preact: Is Preact free?

Yes, open source under the MIT licence.

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
Preact: Can I use React libraries with Preact?

Most, through the preact/compat layer. Compatibility is good but not complete, so libraries relying on React internals can break.

Preact: Why choose Preact over React?

Bundle size, almost always. If payload is not a binding constraint, React’s ecosystem is usually the better trade.

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