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Software Development · head to head

Flagsmith vs LangSmith

Flagsmith logo

Flagsmith

Software Development

Open-source feature flag and remote config platform

From
Free
Rated
-
Full reviewWebsite
LangSmith logo

LangSmith

Software Development

Know what your agents are really doing

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Flagsmith the Free plan supports only a single team member, limiting collaboration for small teams.; LangSmith usage-based pricing applies beyond included traces; LCU charges at $1.50/LCU and LSU at $1.00/LSU
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which Flagsmith and LangSmith actually diverge.

Attributes where Flagsmith and LangSmith differ
AttributeFlagsmithLangSmith
Platformsweb, apiWeb

Identical on both: starting price (Free), pricing model (freemium), free tier (Yes), user rating (Not yet rated), category (Software Development).

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 Flagsmith

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

Only in LangSmith

Nothing recorded that Flagsmith does not also cover.

What people use each for

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

Flagsmith

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

LangSmith

  • Tracing agent execution step-by-step in productionnot Flagsmith
  • Detecting agent failures affecting latency and costnot Flagsmith
  • Monitoring token usage and latency percentilesnot Flagsmith
  • Clustering traces to identify failure modesnot Flagsmith
  • Self-hosting traces within VPC for data residencynot Flagsmith

Where each one falls short

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

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.

LangSmith

  • Usage-based pricing applies beyond included traces; LCU charges at $1.50/LCU and LSU at $1.00/LSU
  • Free tier limited to 1 seat and 5,000 traces per month

Pricing, plan by plan

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

LangSmith

Free
  • DeveloperFree
    • 1 seat maximum
    • 5,000 base traces monthly
  • Plus$39/month
    • Unlimited seats
    • 10,000 base traces monthly
    • 1 free small serverless deployment
  • Enterprise$null/mo
    • Custom pricing
    • Self-hosted and hybrid options
    • Custom SSO, ABAC, RBAC

Which should you pick?

Choose Flagsmith if

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

Choose LangSmith if

  • You want to start without paying.
LangSmith review

Questions people ask

Is Flagsmith or LangSmith better?
Neither clearly leads. Flagsmith starts at Free and LangSmith at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Flagsmith or LangSmith?
Flagsmith starts at Free and LangSmith at Free.
Does Flagsmith or LangSmith run on more platforms?
Flagsmith runs on web, api. LangSmith runs on Web.
Can I use Flagsmith for free?
Both have a free tier, so you can try either at no cost before committing.
What is Flagsmith best used for?
Flagsmith is most often used for gradual feature rollouts across environments, remote configuration without redeploying code, running a/b tests tied to feature flags, self-hosting feature flags for data residency requirements. Of those, gradual feature rollouts across environments and remote configuration without redeploying code are not what LangSmith is typically brought in for.
What can Flagsmith do that LangSmith cannot?
Flagsmith covers Feature flags, Segments, A/B testing, Scheduled flags.

Answered from the vendors’ own pages

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
LangSmith: What does LangSmith cost?

LangSmith Developer plan is free with up to 5,000 base traces monthly. Plus plan costs $39/month per seat with 10,000 base traces included. Enterprise pricing is custom.

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
LangSmith: How does LangSmith usage-based pricing work?

Beyond included traces, LangSmith charges $1.50 per LCU (LangChain Compute Unit) for computational work and $1.00 per LSU (LangChain Storage Unit) for data storage.

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
LangSmith: Is there a free tier for LangSmith?

Yes, the Developer plan is free with limits on seat count (1 seat maximum) and trace volume (5,000 base traces per month).

Source
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