---
title: 'Senior Software Engineer (SDK) at Langfuse'
canonical: 'https://feeny.ai/job/senior-software-engineer-sdk-langfuse-europe-ays8et8hzgp1'
type: 'job'
last_seen: '2026-09-07'
---

# Senior Software Engineer (SDK) at Langfuse

- **Company:** Langfuse
- **Location:** Europe
- **Compensation:** €90k–€160k
- **Employment:** full-time
- **Work type:** hybrid
- **Posted:** 2026-08-26
- **Last confirmed live:** 2026-09-07
- **Apply:** https://jobs.ashbyhq.com/langfuse/891eda0a-a9f6-45e6-8750-71874db8cc11

## Job description

## ABOUT LANGFUSE

Open Source LLM Engineering Platform that helps teams build useful AI applications via tracing, evaluation, and prompt management (mission https://tracking.us.nylas.com/l/6d586a21a6fc4e1a8aacc7eb75882b72/0/82383757e54352130f65066e1b2fc4708aacab7897561bcb8000fe4c8a9c6a21?cache_buster=1761124921, product https://tracking.us.nylas.com/l/6d586a21a6fc4e1a8aacc7eb75882b72/1/b9fba3a93b6ffcc0f99ecda62767a17cc437fe8fe0b16181d1c43c1391212e3d?cache_buster=1761124921). We are now part of ClickHouse.

We're building the "Datadog" of this category; model capabilities continue to improve, but building useful applications is really hard, both in startups and enterprises.

Largest open source solution in this category: trusted by 19 of the Fortune 50, >2k customers, >26M monthly SDK downloads, >6M Docker pulls.

We joined ClickHouse in January 2026 because LLM observability is fundamentally a data problem and Langfuse already ran on ClickHouse. Together we can move faster on product while staying true to open source and self-hosting, and join forces on GTM and sales to accelerate revenue.

Previously backed by Y Combinator, Lightspeed, and General Catalyst.

We're a small, engineering-heavy, and experienced team in Berlin and San Francisco. We are also hiring for engineering in EU timezones and expect one week per month in our Berlin office (how we work https://langfuse.com/handbook/how-we-work/principles).

## WHY SDK ENGINEERING AT LANGFUSE

YOUR WORK WILL HAVE AN OUTSIZED IMPACT.

Our SDKs are downloaded 26M+ times per month. When you ship a new integration or improve SDK performance, thousands of developers benefit the same day — and they'll tell you about it in GitHub issues, on Twitter, and in our community channels. Everything you build is open source (MIT-licensed) and immediately visible.

The SDK is often the very first thing a developer touches when they try Langfuse, so your work directly shapes their first impression.

You will also have direct exposure to how cutting-edge LLM-applications are built. The users you serve are some of the best and most ambitious software engineers in the world and that leverage Langfuse to improve their applications. Deeply understanding the problems they solve will help you design the best possible SDK experience and along the way makes you an expert on LLM engineering yourself.

## YOU WILL GROW AT LANGFUSE BY

- Owning our SDKs. We maintain SDKs in Python and TypeScript both built on OpenTelemetry. You'll be responsible for their reliability, performance, and developer experience. These SDKs run inside our users' production systems, which means they must never fail, must have minimal impact on CPU and memory, and must work flawlessly across every environment — from serverless functions to long-running agent loops. You'll think deeply about the exposed interfaces, error handling, batching, async flushing, and graceful degradation.
- Designing APIs that developers love. How are functions named, how are parameters structured, how are breaking changes communicated, how does the documentation read? Developer experience is a core differentiator for Langfuse and you'll own every detail of it. When we shipped the Python SDK v3 https://langfuse.com/changelog/2025-06-05-python-sdk-v3-generally-available and TypeScript SDK v4 https://langfuse.com/changelog/2025-08-28-typescript-sdk-v4-ga, both were full rewrites on OpenTelemetry — that's the kind of thoughtful, high-impact SDK work you'll lead. Apart from tracing, we also support core workflows of engineers building with LLMs with our SDKs, see our Experiment Runner SDK https://langfuse.com/docs/evaluation/experiments/experiments-via-sdk#experiment-runner-sdk for example.
- Integrating with every major AI framework: Langfuse integrates with 40+ frameworks and model providers: OpenAI SDK, Vercel AI SDK, AI SDK, LangChain, LlamaIndex, Pydantic AI, OpenAI Agents, CrewAI, Amazon Bedrock AgentCore, LiveKit, and many more. You'll maintain these integrations, ensure new Langfuse features are supported across all of them, and add new integrations as the ecosystem evolves. When a new framework gains traction, you'll be among the first to instrument it.
- Maintaining our OpenTelemetry endpoint: some users send traces directly to our OTLP endpoint https://opentelemetry.io/docs/specs/otlp/ instead of using our SDKs. You'll ensure this path is robust, well-documented, and supports the full range of Langfuse features. This also extends our language support to Java, Go, and any language with an OpenTelemetry SDK. You can work with the OpenTelemetry community to steer the GenAI conventions.
- Writing public documentation: you'll own the SDK docs, integration guides, and migration paths. At Langfuse, docs are part of our core product. When you ship a new SDK version or integration, the docs ship with it.

## WHAT WE'RE LOOKING FOR

- Strong engineer who gets excited about developer experience, API design, and writing code that runs reliably in other people's production systems
- Experience building or maintaining SDKs, client libraries, or developer tools — ideally in Python and/or TypeScript
- Deep understanding of performance: you know how to profile, benchmark, and minimize CPU/memory overhead in hot paths
- Someone who can manage projects themselves — you know how to develop strong conviction about what to build and how to ship it
- Thoughtful about versioning, backwards compatibility, and migration paths
- Interest in open source software and genuine excitement about talking to developers about their integration challenges
- Thrives in a small, accountable team where your output is visible and matters
- CS or quantitative degree preferred

Bonus points:

- Experience with OpenTelemetry internals or observability instrumentation
- Former founder or early startup experience
- Contributions to popular open source SDKs or developer tools
- ML/AI background or familiarity with the LLM framework ecosystem

No candidate checks all boxes. If you feel you are a good fit for this role, please go ahead and apply.

## LEARN MORE ABOUT

- SDK Overview https://langfuse.com/docs/observability/sdk/overview — architecture and design of our Python and TypeScript SDKs
- All Integrations https://langfuse.com/integrations — the full list of frameworks, model providers, and gateways we support
- OpenTelemetry Integration https://langfuse.com/integrations/native/opentelemetry — how we use OTEL as the foundation
- SDK Upgrade Paths https://langfuse.com/docs/observability/sdk/upgrade-path — how we think about versioning and breaking changes
- Project you could have built: TypeScript SDK v4 (GA) https://langfuse.com/changelog/2025-08-28-typescript-sdk-v4-ga
- Project you could have built: Python SDK v3 (GA) https://langfuse.com/changelog/2025-06-05-python-sdk-v3-generally-available
- Our codebase: GitHub Repository https://github.com/langfuse/langfuse/
- Ben Kuhn on Impact, Agency and Taste https://www.benkuhn.net/impact/
- Who we are & how we work https://langfuse.com/careers

## PROCESS

We can run the full process to your offer letter in less than 7 days (hiring process https://langfuse.com/handbook/how-we-hire/hiring-process).

## TECH STACK

We run a TypeScript monorepo: Next.js on the frontend, Express workers for background jobs, PostgreSQL for transactional data, ClickHouse for tracing at scale, S3 for file storage, and Redis for queues and caching. You should be familiar with a good chunk of this, but we trust you'll pick up the rest quickly (Stack https://langfuse.com/handbook/product-engineering/tech-stack, Architecture https://langfuse.com/handbook/product-engineering/architecture).

## HOW WE SHIP

Link to handbook https://langfuse.com/handbook/how-we-work/principles

- We trust you to take ownership (ownership overview https://langfuse.com/handbook/how-we-work/ownership) for your area. You identify what to build, propose solutions (RFCs), and ship them. Everyone here thinks about the user experience and the technical implementation at the same time. Everyone manages their own Linear.
- You're never alone. Anyone from the team is happy to go into a whiteboard session with you. 15 minutes of shared discussion can very much improve the overall output.
- We implement maker schedule and communication. There are two recurring meetings a week: Monday check-in on priorities (15 min) and a demo session on Fridays (60 min).
- Code reviews are mentorship. New joiners get all PRs reviewed to learn the codebase, patterns, and how the systems work (onboarding guide https://langfuse.com/handbook/product-engineering/how-we-work/onboarding).
- We use AI as much as possible in our workflows to make our users happy. We encourage everyone to experiment with new tooling and AI workflows.

## WHY LANGFUSE (NOW PART OF CLICKHOUSE)

- This role puts you at the forefront of the AI revolution, partnering with engineering teams who are building the technology that will define the next decade(s).
- This is an open-source devtools company. We ship daily, talk to customers constantly, and fight for great DX. Reliability and performance are central requirements.
- Your work ships under your name. You'll appear on changelog posts https://langfuse.com/changelog for the features you build, and during launch weeks, you'll produce videos https://langfuse.com/blog/2025-10-29-launch-week-4 to announce what you've shipped to the community. You’ll own the full delivery end to end.
- We're solving hard engineering problems: figuring out which features actually help users improve AI product performance, building SDKs developers love, visualizing data-rich traces, rendering massive LLM prompts and completions efficiently in the UI, and processing terabytes of data per day through our ingestion pipeline.
- You'll work closely with the ClickHouse team and learn how they build a world-class infrastructure company. We're in a period of strong growth: Langfuse is growing organically and accelerating through ClickHouse's GTM. (Why we joined ClickHouse https://langfuse.com/blog/joining-clickhouse)
- If you wonder what to build next, our users are a Slack message or a Github discussions post away.
- You’re on a continuous learning journey. The AI space develops at breakneck speed and our customers are at the forefront. We need to be ready to meet them where they are and deliver the tools they need just-in-time.

## About Langfuse

## Company Overview
- **One-liner**: Langfuse is an open-source AI engineering platform that provides observability, prompt management, evaluations, and analytics for teams building LLM applications.
- **Entity Type**: Private (Acquired by ClickHouse in January 2026)
- **Headquarters**: San Francisco, USA & Berlin, Germany
- **Founded**: 2022
- **Founders**: Marc Klingen (CEO), Max Deichmann (CTO), Clemens Rawert (COO)

## Core Business
- **Primary industry**: AI Engineering / LLM Observability & Evaluation
- **Target customers**: B2B, Enterprise, and Developer teams building LLM applications
- **Mission**: To help teams build, monitor, and improve LLM applications across the full development lifecycle, enabling more AI applications to reach production

## Products & Services
- **Langfuse Platform**: An integrated open-source (MIT licensed) platform combining observability (hierarchical traces), prompt management, evaluations (LLM-as-a-judge, heuristics, human review), experiments, and analytics dashboards. It covers the full LLM engineering loop from prototype to production.
- **Self-Hosted Deployment**: Available via Docker Compose, Kubernetes (Helm), and Terraform for AWS, GCP, and Azure. Scales to billions of monthly events.
- **Cloud / Managed Service**: Free tier (50k observations/month) and paid enterprise tiers with 99.9% uptime SLA.
- **SDKs & Integrations**: Native SDKs for Python, TypeScript, Go, Java, .NET, Ruby, PHP, Swift; OTel-native; 100+ integrations with frameworks (LangChain, Vercel AI SDK, CrewAI) and model providers (OpenAI, Anthropic, Google Gemini).
- **MCP Server & CLI**: Developer tools for interacting with Langfuse from IDEs and CI/CD pipelines.

## Market Standing
- **Valuation/Market Cap**: Not disclosed (acquired by ClickHouse in January 2026)
- **Key Metric**: Processes 10+ billion observations per month; 50M+ SDK installs/month; 2,300+ customers
- **Notable Investors/Partners**: Backed by Lightspeed, General Catalyst, Y Combinator, and angel investors. Acquired by ClickHouse (January 2026). Used by 19 of the Fortune 50, including Canva, Samsara, Twilio, Khan Academy, and Intuit.
- **Growth Signals**: Acquired by ClickHouse in January 2026; 22,000+ GitHub stars; 5,000+ Discord members; 100,000+ engineers building on the platform; team grew to 19 people (as of YC profile); 50M+ SDK installs/month.

## Competitive Advantages
- **Open Source (MIT License)**: Full product features are MIT licensed, allowing self-hosting, forking, and modification — no vendor lock-in.
- **OTel Native & Async by Default**: Works with standard OpenTelemetry instrumentation and never blocks application performance.
- **Built for Scale**: ClickHouse OLAP backend enables querying millions of traces in milliseconds; processes 10+ billion observations/month.
- **Full Lifecycle Platform**: Combines observability, prompt management, evals, experiments, and human annotation in one integrated workflow — not just a point solution.
- **Enterprise Trust**: Used by 19 of the Fortune 50, with strong security and compliance posture.

## Strategic Focus
- **Post-Acquisition Growth**: Joining ClickHouse to accelerate growth, likely focusing on deeper integration with ClickHouse's OLAP database and expanding enterprise reach.
- **Developer Experience**: Continued investment in MCP servers, CLI tools, and coding agent integrations (Claude Code, Cursor, Codex) to make the platform "made for developers, loved by agents."
- **Open Source Community**: Maintaining the largest OSS community in the LLM observability category, with weekly releases and community hours.

## Why Work Here
- **Strong Traction & Impact**: Work on a platform used by 19 of the Fortune 50, processing 10+ billion observations/month — your work directly impacts how the world's leading AI teams ship production LLM applications.
- **Remote-First with In-Person Connection**: European roles are remote-first with one week per month in Berlin (travel covered); SF and Berlin locals use the office when useful. Flexible, async-friendly culture.
- **Transparent Culture**: Everything is public — the company handbook, core principles, processes, and metrics. Radical transparency for alignment and community trust.
- **Acquired by ClickHouse**: Joining a larger, well-funded infrastructure company (ClickHouse) provides stability, resources, and a broader platform for growth while maintaining Langfuse's product identity.
- **Small, High-Impact Team**: ~19 people as of acquisition, meaning significant ownership and influence for new hires.
- **Open Source Ethos**: MIT-licensed codebase, active community (22k+ GitHub stars, 5k Discord members), and a culture of contribution.

## Sources
1. [langfuse.com](https://langfuse.com/)
2. [langfuse.com/careers](https://langfuse.com/careers)
3. [jobs.ashbyhq.com/langfuse](https://jobs.ashbyhq.com/langfuse)
4. [ycombinator.com/companies/langfuse](https://www.ycombinator.com/companies/langfuse)
5. [github.com/langfuse/langfuse](https://github.com/langfuse/langfuse)

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