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ConfigCat vs Express.js

ConfigCat logo

ConfigCat

Developer Tools

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

From
Free
Free plan
Yes
Full reviewWebsite
Express.js logo

Express.js

Web Development

Fast, unopinionated, minimalist web framework for Node.js

From
Free
Free plan
Yes
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.; Express.js governed by the OpenJS Foundation with no vendor or paid tier, per expressjs.com; as open source software it has no pricing to compare
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which ConfigCat and Express.js actually diverge.

Attributes where ConfigCat and Express.js differ
AttributeConfigCatExpress.js
Pricing modelPer month by feature flag and environment countopen-source
PlatformsWeb, API, iOS, Android, Node.js, .NET, Java, Python, GoWeb
CategoryDeveloper ToolsWeb Development

Identical on both: starting price (Free), 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 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 Express.js

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 Express.js
  • A team that wants every engineer, product manager and support agent to have a login without paying per seatnot Express.js
  • Decoupling deployment from release with percentage rollouts and a kill switch, without buying an experimentation platformnot Express.js
  • A small team that needs ten flags permanently and can run indefinitely on the free tiernot Express.js

Express.js

  • Web server and API developmentnot ConfigCat
  • REST API creationnot ConfigCat
  • Backend application developmentnot ConfigCat
  • Node.js web applicationsnot 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.

Express.js

  • Governed by the OpenJS Foundation with no vendor or paid tier, per expressjs.com; as open source software it has no pricing to compare
  • Express.js provides only a thin layer of fundamental routing features by its own description, requiring separate middleware modules for functionality like body parsing, sessions or authentication

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

Express.js

Free

No published plan breakdown. See the Express.js 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 Express.js if

  • You want to start without paying.
Express.js review

Questions people ask

Is ConfigCat or Express.js better?
Neither clearly leads. ConfigCat starts at Free and Express.js at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, ConfigCat or Express.js?
ConfigCat starts at Free and Express.js at Free.
Does ConfigCat or Express.js run on more platforms?
ConfigCat runs on Web, API, iOS, Android, Node.js, .NET, Java, Python, Go. Express.js 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 Express.js is typically brought in for.
What can ConfigCat do that Express.js 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.

Express.js: Is Express.js free?

Yes, Express.js is completely free and open source. The framework is maintained by the OpenJS Foundation and available via npm at no cost. Installation is as simple as running npm install express.

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.

Express.js: Does Express.js offer commercial support?

Express.js itself is free with no official commercial support from the project. Community support is available through documentation and community resources at no cost. Third-party vendors may offer commercial support services, though none are listed on the official website.

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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