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Developer Tools · head to head

ConfigCat vs Keil MDK

ConfigCat logo

ConfigCat

Developer Tools

Feature flag service priced per flag and environment with unlimited seats and unlimited monthly active users

From
Free
Rated
-
Full reviewWebsite
Keil MDK logo

Keil MDK

Developer Tools

Microcontroller Development Kit for Arm-based devices

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: ConfigCat there is no experimentation or statistical analysis engine, so teams wanting real A/B tests with significance testing must buy and integrate a separate analytics or experimentation product.; Keil MDK pricing for Essential and Professional subscriptions not disclosed on primary site
  • Prices and features above were last checked on 31 August 2026.

Where they differ

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

Attributes where ConfigCat and Keil MDK differ
AttributeConfigCatKeil MDK
Pricing modelPer month by feature flag and environment countfreemium
PlatformsWeb, API, iOS, Android, Node.js, .NET, Java, Python, GoWeb

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 ConfigCat

  • Feature flags and configuration
  • Percentage rollouts
  • Targeting rules and segments
  • Unlimited seats
  • Global CDN delivery
  • Audit log
  • Public API and webhooks
  • SDKs across languages

Only in Keil MDK

Nothing recorded that ConfigCat does not also cover.

What people use each for

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

ConfigCat

  • A consumer or mobile app with millions of users where per-MAU flag pricing would cost more than the flags are worthnot Keil MDK
  • A team that wants every engineer, product manager and support agent to have a login without paying per seatnot Keil MDK
  • Decoupling deployment from release with percentage rollouts and a kill switch, without buying an experimentation platformnot Keil MDK
  • A small team that needs ten flags permanently and can run indefinitely on the free tiernot Keil MDK

Keil MDK

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

Where each one falls short

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

ConfigCat

  • There is no experimentation or statistical analysis engine, so teams wanting real A/B tests with significance testing must buy and integrate a separate analytics or experimentation product.
  • Pricing by flag count punishes exactly the hygiene you want: the Pro tier caps at 100 flags, so teams that do not aggressively retire stale flags are pushed to the 325 dollar Smart tier for housekeeping reasons rather than growth.
  • The free tier allows only 2 environments, which does not cover the common development, staging and production split, so almost any real deployment starts on a paid plan.
  • It is a smaller vendor than the category incumbents, so enterprise procurement teams will find less depth in compliance attestations, contractual terms and reference architecture than LaunchDarkly offers.
  • Flag evaluation relies on SDK-side caching of a CDN-delivered config, which is fast but means propagation of a change is eventually consistent rather than instant, something to understand before relying on it as an emergency kill switch.

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

ConfigCat

Free
  • Forever FreeFree
    • 10 feature flags
    • 2 environments and 2 products
    • 2 segments
  • Pro$110/month
    • 100 feature flags
    • 3 environments and 3 products
    • Unlimited seats and MAUs
  • Smart$325/month
    • Unlimited feature flags
    • Unlimited environments, products and segments
    • Unlimited seats and MAUs
  • Enterprise$900/month
    • Everything in Smart
    • Enterprise support and controls
    • Unlimited everything on flag counts

Keil MDK

Free

No published plan breakdown. See the Keil MDK review.

Which should you pick?

Choose ConfigCat if

  • You need feature flags and configuration.
  • You want to start without paying.
  • You work on Web, API, iOS, Android, Node.js, .NET, Java, Python, Go.
  • You also want percentage rollouts.
ConfigCat review

Choose Keil MDK if

  • You want to start without paying.
Keil MDK review

Questions people ask

Is ConfigCat or Keil MDK better?
Neither clearly leads. ConfigCat 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, ConfigCat or Keil MDK?
ConfigCat starts at Free and Keil MDK at Free.
Does ConfigCat or Keil MDK run on more platforms?
ConfigCat runs on Web, API, iOS, Android, Node.js, .NET, Java, Python, Go. Keil MDK runs on Web.
Can I use ConfigCat for free?
Both have a free tier, so you can try either at no cost before committing.
What is ConfigCat best used for?
ConfigCat is most often used for a consumer or mobile app with millions of users where per-mau flag pricing would cost more than the flags are worth, a team that wants every engineer, product manager and support agent to have a login without paying per seat, decoupling deployment from release with percentage rollouts and a kill switch, without buying an experimentation platform, a small team that needs ten flags permanently and can run indefinitely on the free tier. Of those, a consumer or mobile app with millions of users where per-mau flag pricing would cost more than the flags are worth and a team that wants every engineer, product manager and support agent to have a login without paying per seat are not what Keil MDK is typically brought in for.
What can ConfigCat do that Keil MDK cannot?
ConfigCat covers Feature flags and configuration, Percentage rollouts, Targeting rules and segments, Unlimited seats.

Answered from the vendors’ own pages

ConfigCat: How is ConfigCat priced?

By feature flag, environment and product count. Seats, monthly active users and flag reads are unlimited on every plan.

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
ConfigCat: Is the free tier usable?

For small projects yes, but at 10 flags and 2 environments it will not cover a dev, staging and production setup.

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
ConfigCat: Can it run A/B tests?

It can split traffic, but there is no statistics engine. You need a separate analytics tool to decide a winner.

ConfigCat: How fast does a flag change take effect?

SDKs poll and cache, so changes propagate on the polling interval rather than instantly.

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