LangSmith vs Promptfoo
A side-by-side comparison of LangSmith and Promptfoo, drawn from Ignaite's continuously-verified listings.
Compared from listings verified as of
At a glance
| Attribute | LangSmith | Promptfoo |
|---|---|---|
| Category (differs) | Observability | Eval |
| Pricing (differs) | FREEMIUM | FREE |
| License (differs) | Proprietary | Open source |
| Deployment (differs) | Cloud | — |
| Platforms (differs) | API, Web | CLI, macOS, Windows, Linux |
| Model support (differs) | Model-agnostic | BYO key / model |
| Vendor (differs) | LangChain | Promptfoo |
| Capabilities (differs) |
|
|
The honest brief
LangSmith
Deepest native LangChain/LangGraph tracing — but cloud-only, where Langfuse lets you self-host the same.
- Native LangChain/LangGraph tracing
- Works standalone via SDKs
- Datasets + eval orchestration
- Prompt playground built in
- Closed source, cloud-only
- Self-host is Enterprise-only
- Best value inside LangChain stack
Promptfoo
Define evals in plain YAML and run one goldset across models in CI — a prompt regression fails the build like any other test.
- YAML-driven, version-controllable evals
- Runs in CI, model-agnostic
- Goldsets and rubric scoring
- Also does red-teaming/security scans
- CLI-first, less of a hosted UI
- Teams may want managed dashboards
- Config sprawl on large eval suites
When to pick which
Both cover LLM evaluation.
Pick LangSmith if you need LLM observability and Prompt management.
- LLM observability (primary capability)
- Prompt management (secondary capability)
Pick Promptfoo if you need Red-teaming and Guardrails.
- Red-teaming (primary capability)
- Guardrails (secondary capability)
Promptfoo leans on LLM evaluation as a headline capability; LangSmith treats it as secondary.
- LLM evaluation (primary capability)
They also differ on:
- Pricing
- FREEMIUM · FREE
- License
- Proprietary · Open source
- Platforms
- API, Web · CLI, macOS, Windows, Linux