Criterion LangChain Langfuse
CategoryAI Agents & FrameworksMachine Learning & Deep Learning
In one sentenceOpen-source framework for building LLM apps and agents that work with many model providers.Open-source tracing, prompt management and evaluation for LLM applications, self-hosted or in the cloud.
Problem it solvesWiring models, tools, data sources and agent logic together without writing custom glue for every provider.Understanding and improving LLM app behaviour, cost and quality in production.
Free planYesYes
Developer APIYes — docsYes — docs
Open sourceYesYes
PlatformsPython, JavaScript/TypeScriptWeb (cloud), Docker, Kubernetes, Python SDK, JS/TS SDK
Pricing (summary)The LangChain framework is free under the MIT licence. LangSmith, sold separately, has a free Developer plan (1 seat, 5k base traces/month), Plus at $39/seat/month with 10k traces, and custom Enterprise.
Checked 2026-10-19
Self-hosting the open-source core is free. Langfuse Cloud: Hobby free (50k units/month), Core $29/month, Pro $199/month and Enterprise $2,499/month, each with 100k units included and graduated overage from $8 per 100k units.
Checked 2026-10-19
Strengths
  • Free and open source
  • Very broad ecosystem
  • Works across many providers
  • Open source with full self-hosting
  • Broad integrations
  • Transparent usage pricing
Limitations
  • Abstractions add complexity for simple apps
  • You still pay model providers separately
  • Observability and deployment require LangSmith, a paid product beyond the free tier
  • Enterprise (ee) features are outside the MIT licence
  • Hobby plan limited to 2 users and 30-day data access
  • Self-hosting requires infrastructure work