LangSmith vs SpacePrompts
LangSmith
langchain.comSpacePrompts
spaceprompts.comSide by side
| Figure | LangSmith | SpacePrompts |
|---|---|---|
| Price from | $39/mo | $5/mo |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | — |
| macOS | Yes | — |
| Linux | Yes | — |
| API | Yes | Yes |
| Self-hosted | Yes | — |
| Plans published | 3 | 3 |
| Spec score · Prompting Tool | 9.3 (#2) | 8.4 (#3) |
| Evaluation | Evaluation supports offline datasets, online production evaluations, human annotation queues and side-by-side experiment comparison. | The Evaluator scores prompts, identifies weak areas, and offers guidance to improve them. |
| Founded | 2023 | SourceForge lists the company as founded in 2025. |
| Integrations | Documented integrations cover OpenAI, Anthropic, Bedrock, Gemini, Mistral, LiteLLM, OpenTelemetry, CrewAI, Vercel AI SDK, PydanticAI, AutoGen and many other frameworks and providers. | The privacy policy lists Google, GitHub, and Microsoft as OAuth providers for account authentication. |
| Support | The Developer plan includes community support, and the Enterprise plan lists a support SLA. | The site directs users to a contact form and says replies typically arrive within 24 hours. |
| What it does | LangSmith is LangChain's framework-agnostic platform for observing, evaluating and deploying AI agents. | SpacePrompts manages, runs, versions, shares and retrieves AI prompts for individuals and teams. |
Plans
In their own words
LangSmith
LangSmith is a commercial agent-engineering platform for building, evaluating, deploying, monitoring, and improving AI agents. It supports offline evaluations on curated datasets and real-time scoring of production interactions. Evaluation methods include human review, heuristic checks, LLM-as-judge evaluators, pairwise comparisons, and custom Python or TypeScript evaluators. Annotation queues route runs to subject-matter experts for feedback that can calibrate evaluations, improve prompts, or augment datasets. The Playground compares prompt versions or model providers, and LangSmith chat can auto-improve prompts. Observability includes agent and retrieval tracing, token and general cost tracking, trajectory monitoring, online evaluations, and webhook or PagerDuty alerts. Traces can arrive through SDKs or an API from LangGraph, custom Python, or other stacks; SDKs are listed for Python, TypeScript, Go, and Java. Hosting ranges from cloud to hybrid and self-hosted Enterprise options. The Developer plan costs nothing, Plus costs $39 a month, and Enterprise pricing is custom.
SpacePrompts
SpacePrompts is a prompt management platform for people and teams working with AI. It runs on the web, through an API, and with Chrome, Edge, and Firefox extensions. Users can save, organize, run, version, and reuse prompts. The Playground combines an editor, variables, model selection, and immediate runs. An Evaluator scores prompts, highlights weak areas, and gives improvement guidance. Every save creates a version that can be restored later. The prompt manager extension can turn highlighted webpage text into a prompt. Its token counter supports OpenAI, Claude, Gemini, and DeepSeek models, showing token counts and estimated costs. Pro and Team plans provide API access, limited to 60 requests per minute per key. Team workspaces add shared libraries, collaborative editing, and role permissions for up to five members. Free includes 50 prompts and daily usage limits; Pro is $5 a month billed annually, and Team is $9 a month billed annually.