--- title: How to Build End-to-End LLM Observability in FastAPI... description: A practical guide to implementing end-to-end LLM observability in FastAPI using the OpenTelemetry Python SDK without relying on vendor-specific agents. Covers... canonical: https://daily.dev/posts/how-to-build-end-to-end-llm-observability-in-fastapi-with-opentelemetry-n6rfzz43o twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: How to Build End-to-End LLM Observability in FastAPI with OpenTelemetry | daily.dev og:description: A practical guide to implementing end-to-end LLM observability in FastAPI using the OpenTelemetry Python SDK without relying on vendor-specific agents. Covers... og:url: https://daily.dev/posts/how-to-build-end-to-end-llm-observability-in-fastapi-with-opentelemetry-n6rfzz43o og:image: https://api.daily.dev/og/posts/n6RFZz43O.png og:image:alt: How to Build End-to-End LLM Observability in FastAPI with OpenTelemetry og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # How to Build End-to-End LLM Observability in FastAPI with OpenTelemetry **[freeCodeCamp](https://daily.dev/sources/freecodecamp)** · 24 min read · 3 upvotes · 0 comments ## Summary A practical guide to implementing end-to-end LLM observability in FastAPI using the OpenTelemetry Python SDK without relying on vendor-specific agents. Covers designing a span hierarchy for a RAG pipeline with spans for retrieval, LLM invocation, and post-processing. Explains how to capture semantic attributes including prompt metadata (hashed for privacy), token usage, estimated cost, and model configuration. Also covers evaluation hooks for attaching quality signals to traces, exporting to backends like Jaeger, Grafana Tempo, or Arize Phoenix, and best practices around sampling, privacy, and anti-patterns. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [How to Integrate OpenTelemetry With a FastAPI App Quiz – Real Python](https://daily.dev/posts/how-to-integrate-opentelemetry-with-a-fastapi-app-quiz-real-python-jo7qgfcoc) · Real Python · 2 upvotes · 0 comments - [Why Observability Matters \(More\!\) with AI Applications](https://daily.dev/posts/why-observability-matters-more-with-ai-applications-gdao7ywr7) · InfoQ · 1 upvotes · 0 comments - [The complete guide to LLM observability for 2026](https://daily.dev/posts/the-complete-guide-to-llm-observability-for-2026-vabqmevzx) · portkey · 1 upvotes · 0 comments - [What a Useful AI Trace Should Actually Contain \+ Build One](https://daily.dev/posts/what-a-useful-ai-trace-should-actually-contain-build-one-4avkgyjsk) · Telerik · 0 upvotes · 0 comments - [The lazy developer’s guide to observing your own code](https://daily.dev/posts/the-lazy-developer-s-guide-to-observing-your-own-code-zvcqnpe8i) · CNCF · 1 upvotes · 0 comments --- Tags: [#devops](https://daily.dev/tags/devops), [#fastapi](https://daily.dev/tags/fastapi), [#llm-observability](https://daily.dev/tags/llm-observability), [#opentelemetry](https://daily.dev/tags/opentelemetry), [#rag](https://daily.dev/tags/rag) [View this post on daily.dev](https://daily.dev/posts/how-to-build-end-to-end-llm-observability-in-fastapi-with-opentelemetry-n6rfzz43o) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"How to Build End-to-End LLM Observability in FastAPI with OpenTelemetry","url":"https://daily.dev/posts/how-to-build-end-to-end-llm-observability-in-fastapi-with-opentelemetry-n6rfzz43o","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/how-to-build-end-to-end-llm-observability-in-fastapi-with-opentelemetry-n6rfzz43o"},"datePublished":"2026-03-13T20:32:19.562Z","dateModified":"2026-07-16T02:12:45.756Z","description":"A practical guide to implementing end-to-end LLM observability in FastAPI using the OpenTelemetry Python SDK without relying on vendor-specific agents. 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