{"slug": "spanlens", "title": "Spanlens", "summary": "Spanlens, an MIT-licensed LLM observability platform, offers a drop-in replacement for OpenAI, Anthropic, and Gemini SDKs, providing full visibility into LLM requests without agents or infrastructure setup. It supports multiple providers and frameworks, is fully self-hostable, and offers a free self-hosted option with no usage cap, positioning itself as a LangSmith alternative with flat monthly pricing.", "body_md": "Get **20% off** with code **LAUNCH20**\n\nLast 30 days\n\nLast commit\n\nRepository age\n\nLicense\n\nSelf-hosted\n\nRepository\n\nSpanlens is an MIT-licensed LLM observability platform that gives you full visibility into every request your app makes to OpenAI, Anthropic, or Gemini. It works as a drop-in replacement for the provider SDK, so you swap one import and start seeing data immediately. No agents to run, no infrastructure to wire up.\n\nIt's built for teams shipping LLM-powered products who need to answer real questions fast: why did the bill spike, which agent step is slow, did the new prompt actually improve quality?\n\nCore capabilities:\n\nSpanlens supports OpenAI, Anthropic, Google Gemini, Mistral, Azure, Bedrock, and Vertex, plus framework integrations for LangChain, LlamaIndex, Vercel AI SDK, and LangGraph. It also ingests OpenTelemetry spans over OTLP/HTTP.\n\nFor teams that can't send prompt data to a third party, it's fully self-hostable. Prompts and completions stay inside your own network. Data can be exported as JSON, CSV, or Parquet, or streamed to S3 or BigQuery.\n\nIf you're evaluating [LangSmith alternatives](/alternatives/langsmith), Spanlens covers similar ground with a flat monthly pricing model rather than per-seat fees, and a free self-hosted option that has no usage cap.\n\nLast 30 days\n\nLast commit\n\nRepository age\n\nLicense\n\nSelf-hosted\n\nRepository\n\nEvery Sunday we deconstruct one proprietary app and pick the best open source alternatives worth switching to.\n\nStars\n\nLast commit\n\nLicense\n\nStars\n\nLast commit\n\nLicense\n\nStars\n\nLast commit\n\nLicense\n\nStars\n\nLast commit\n\nLicense\n\nCompare with\n\nStars\n\nStars\n\nStars\n\nStars\n\nStars\n\nStars\n\nLast commit\n\nLicense\n\nCompare with\n\nLast commit\n\nLicense\n\nCompare with\n\nLast commit\n\nLicense\n\nCompare with\n\nLast commit\n\nLicense\n\nCompare with\n\nLast commit\n\nLicense\n\nCompare with\n\nLast commit\n\nLicense\n\nCompare with", "url": "https://wpnews.pro/news/spanlens", "canonical_source": "https://openalternative.co/spanlens?utm_source=openalternative.co&utm_medium=rss", "published_at": "2026-07-29 09:59:00+00:00", "updated_at": "2026-08-19 02:41:35.803605+00:00", "lang": "en", "topics": ["developer-tools"], "entities": ["Spanlens", "OpenAI", "Anthropic", "Gemini", "LangSmith", "LangChain", "LlamaIndex", "Vercel AI SDK"], "alternates": {"html": "https://wpnews.pro/news/spanlens", "markdown": "https://wpnews.pro/news/spanlens.md", "text": "https://wpnews.pro/news/spanlens.txt", "jsonld": "https://wpnews.pro/news/spanlens.jsonld"}}