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Developer Tools · head to head

Keil MDK vs Restate

Keil MDK logo

Keil MDK

Developer Tools

Microcontroller Development Kit for Arm-based devices

From
Free
Rated
-
Full reviewWebsite
Restate logo

Restate

Developer Tools

Durable execution engine in Rust with a free tier and low-latency workflows

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Keil MDK pricing for Essential and Professional subscriptions not disclosed on primary site; Restate the runtime is under a Business Source Licence rather than an open source licence, so building a competing managed offering on it is prohibited and some procurement functions will reject it on licence grounds alone.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

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

Attributes where Keil MDK and Restate differ
AttributeKeil MDKRestate
Pricing modelfreemiumPer month by durable action count
PlatformsWebLinux, macOS, Web

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Developer Tools).

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 Restate does not also cover.

Only in Restate

  • Durable execution
  • Virtual objects
  • Single binary runtime
  • Multi-language SDKs
  • Workflows and sagas
  • Restate Cloud

What people use each for

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

Keil MDK

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

Restate

  • Payment or order flows where a crash between two external API calls must not double-charge or lose the ordernot Keil MDK
  • AI agent loops that call tools over minutes or hours and must survive a deployment mid-runnot Keil MDK
  • Replacing hand-rolled retry, idempotency key and outbox code across a set of microservicesnot Keil MDK
  • A small team that wants durable workflows without operating a Temporal cluster and its databasenot 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

Restate

  • The runtime is under a Business Source Licence rather than an open source licence, so building a competing managed offering on it is prohibited and some procurement functions will reject it on licence grounds alone.
  • Restate Cloud jumps from a free fifty thousand actions straight to 300 US dollars a month for twenty million, so a workload sitting at a few hundred thousand actions pays enterprise-shaped money for hobby-shaped volume.
  • It is a young project against Temporal’s established base, so hiring engineers who already know it is unrealistic and the answer to most questions is in the docs rather than on Stack Overflow.
  • The programming model requires structuring code around durable handlers and virtual objects, which is a genuine rewrite for existing services rather than a library you add.
  • The single-binary simplicity that makes small deployments cheap also means fewer operational knobs at very large scale than a system designed as separable components.

Pricing, plan by plan

Keil MDK

Free

No published plan breakdown. See the Keil MDK review.

Restate

Free
  • FreeFree
    • Fifty thousand durable actions per month
    • No credit card required
    • Community support
  • Starter$300/month
    • Twenty million actions per month
    • Two hundred actions per second, bursting to one thousand
    • Twenty GB storage
  • Pro$1000/month
    • Fifty million actions per month
    • Five hundred actions per second, bursting to two thousand
    • Fifty GB storage
  • Enterprise$undefined/year
    • Negotiated volume
    • Twenty-four seven P0 support
    • 99.99 per cent SLA

Which should you pick?

Choose Keil MDK if

  • You want to start without paying.
Keil MDK review

Choose Restate if

  • You need durable execution.
  • You want to start without paying.
  • You work on Linux, macOS, Web.
  • You also want virtual objects.
Restate review

Questions people ask

Is Keil MDK or Restate better?
Neither clearly leads. Keil MDK starts at Free and Restate at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Keil MDK or Restate?
Keil MDK starts at Free and Restate at Free.
Does Keil MDK or Restate run on more platforms?
Keil MDK runs on Web. Restate runs on Linux, macOS, Web.
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 Restate is typically brought in for.
What can Keil MDK do that Restate cannot?
Restate covers Durable execution, Virtual objects, Single binary runtime, Multi-language SDKs.

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
Restate: Is Restate open source?

The SDKs are MIT. The runtime is under a Business Source Licence, which permits self-hosting but not offering it as a competing service.

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
Restate: How does it compare with Temporal?

Same problem, different shape: one Rust binary with embedded storage instead of a server plus database plus workers, and lower per-step latency.

Restate: Is there a free tier?

Yes, fifty thousand durable actions a month on Restate Cloud with no card required.

Restate: Which languages are supported?

TypeScript, Java, Kotlin, Go, Python and Rust.

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