Softwr

Developer Tools · head to head

ESLint vs Flagsmith

ESLint logo

ESLint

Developer Tools

Find and fix problems in JavaScript code

From
Free
Rated
-
Full reviewWebsite
Flagsmith logo

Flagsmith

Software Development

Open-source feature flag and remote config platform

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: ESLint slow performance on large codebases compared to newer tools like Oxlint and Biome; Flagsmith the Free plan supports only a single team member, limiting collaboration for small teams.

Where they differ

Only the attributes on which ESLint and Flagsmith actually diverge.

Attributes where ESLint and Flagsmith differ
AttributeESLintFlagsmith
Pricing modelUnknownfreemium
PlatformsBrowser-based JavaScript, Node.js, Any JavaScript environmentweb, api
CategoryDeveloper ToolsSoftware Development
Founded2019Unknown

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 ESLint

Nothing recorded that Flagsmith does not also cover.

Only in Flagsmith

  • Feature flags
  • Segments
  • A/B testing
  • Scheduled flags
  • SDKs
  • SAML/SSO

What people use each for

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

ESLint

  • Statically analysing JavaScript and JSX to find problems before runtimenot Flagsmith
  • Automatically fixing issues with syntax-aware rewritesnot Flagsmith
  • Enforcing a consistent code style across a teamnot Flagsmith
  • Running as a CI step to block non-conforming codenot Flagsmith
  • Writing custom rules for project-specific conventionsnot Flagsmith

Flagsmith

  • Gradual feature rollouts across environmentsnot ESLint
  • Remote configuration without redeploying codenot ESLint
  • Running A/B tests tied to feature flagsnot ESLint
  • Self-hosting feature flags for data residency requirementsnot ESLint

Where each one falls short

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

ESLint

  • Slow performance on large codebases compared to newer tools like Oxlint and Biome
  • Complexity in configuration from scratch, particularly for TypeScript support
  • Limited built-in TypeScript support, requiring separate parsers and coordination with new TypeScript features

Flagsmith

  • The Free plan supports only a single team member, limiting collaboration for small teams.
  • Exceeding request limits triggers overage charges after a one-time 30-day grace period.
  • Enterprise-grade SSO and governance are locked behind the Scale-Up and Enterprise tiers.
  • Self-hosting requires operating and updating the platform yourself, unlike a fully managed SaaS competitor.

Pricing, plan by plan

ESLint

Free

No published plan breakdown. See the ESLint review.

Flagsmith

Free
  • FreeFree
    • Up to 50,000 requests/month
    • 1 team member
    • Unlimited feature flags, environments, identities and segments
  • Start-Up$45/month
    • Up to 1,000,000 requests/month
    • 3 team members
    • Scheduled flags, 2FA, A/B testing, integrations, email support
  • Scale-Up$300/month
    • 5,000,000+ requests/month
    • 5-20 team members
    • SAML/SSO, governance features, priority support

Which should you pick?

Choose ESLint if

  • You want to start without paying.
  • You work on Browser-based JavaScript, Node.js, Any JavaScript environment.
ESLint review

Choose Flagsmith if

  • You need feature flags.
  • You want to start without paying.
  • You work on web, api.
  • You also want segments.
Flagsmith review

Questions people ask

Is ESLint or Flagsmith better?
Neither clearly leads. ESLint starts at Free and Flagsmith at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, ESLint or Flagsmith?
ESLint starts at Free and Flagsmith at Free.
Does ESLint or Flagsmith run on more platforms?
ESLint runs on Browser-based JavaScript, Node.js, Any JavaScript environment. Flagsmith runs on web, api.
Can I use ESLint for free?
Both have a free tier, so you can try either at no cost before committing.
What is ESLint best used for?
ESLint is most often used for statically analysing javascript and jsx to find problems before runtime, automatically fixing issues with syntax-aware rewrites, enforcing a consistent code style across a team, running as a ci step to block non-conforming code. Of those, statically analysing javascript and jsx to find problems before runtime and automatically fixing issues with syntax-aware rewrites are not what Flagsmith is typically brought in for.
What can ESLint do that Flagsmith cannot?
Flagsmith covers Feature flags, Segments, A/B testing, Scheduled flags.

Answered from the vendors’ own pages

ESLint: Does ESLint automatically fix code issues?

Many problems ESLint finds can be automatically fixed via the --fix flag. ESLint fixes are syntax-aware so you won't experience errors introduced by traditional find-and-replace algorithms.

Source
Flagsmith: What does Flagsmith cost?

Flagsmith has a Free plan, a Start-Up plan from $40-45/month, a Scale-Up plan from $250-300/month, and custom Enterprise pricing.

Source
ESLint: How much does ESLint cost?

ESLint is completely free and open-source software maintained by the OpenJS Foundation. The project accepts voluntary donations from sponsors.

Source
Flagsmith: Is there a free plan, and what are its limits?

The Free plan supports up to 50,000 requests per month and 1 team member, with unlimited feature flags, environments, identities and segments.

Source
ESLint: Can I write custom ESLint rules?

Yes. You can develop custom rules that work alongside built-in functionality through ESLint's plugin system, allowing complete customization for your project needs.

Source
Flagsmith: How is usage metered?

Usage is metered by monthly API requests; exceeding a plan's limit triggers overage charges starting around $50 per million requests, with a 30-day grace period the first time a paid plan exceeds its limit.

Source
Share

Related pages

More on ESLint

More on Flagsmith

Keep looking

Other head to heads