Langfuse - Senior Software Engineer, SDK

ClickHouse; Paris; À distance; EUR 90 000 - 160 000; Plein temps

Avantages offerts par ce poste

Flexible work environment

Healthcare

Equity in the company

Time off

Home office setup

Global Gatherings

Résumé du poste

ClickHouse in Paris is hiring for a developer to shape our SDK experience. You’ll own Python and TypeScript SDKs, optimize performance, and design intuitive APIs that developers love. You will work across frameworks, ensure robust OpenTelemetry integrations, and expand our SDK docs and upgrade paths.

You’ll collaborate with a small, focused team in a remote-friendly setup, contributing to open-source projects and improving developer experience for thousands of users worldwide.

Qualifications

• Strong engineer excited about developer experience, API design and reliable production code.
• Experience building or maintaining SDKs, client libraries, or developer tools in Python and/or TypeScript.
• Deep understanding of performance: profiling, benchmarking and minimizing CPU/memory overhead.

Responsabilités

• Own SDKs in Python and TypeScript; ensure reliability, performance and developer experience.
• Design APIs and developer docs; maintain breaking-change policies and docs quality.
• Integrate with major AI frameworks and maintain new integrations as ecosystem evolves.
• Maintain OTLP/OpenTelemetry endpoint support and multi-language exposure.
• Write public documentation and migration guides for SDKs and integrations.

Connaissances

OpenTelemetry

SDK development

APIs design

Python

TypeScript

Formation

CS or quantitative degree

Outils

OpenTelemetry

Description du poste

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.

Why SDK Engineering at Langfuse

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 and TypeScript SDK v4, 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 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 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

Learn More About

• SDK Overview — architecture and design of our Python and TypeScript SDKs
• All Integrations — the full list of frameworks, model providers, and gateways we support
• OpenTelemetry Integration — how we use OTEL as the foundation
• SDK Upgrade Paths — how we think about versioning and breaking changes
• Project you could have built: TypeScript SDK v4 (GA)
• Project you could have built: Python SDK v3 (GA)
• Our codebase: GitHub Repository
• Ben Kuhn on Impact, Agency and Taste
• Who we are & how we work

Perks

• Flexible work environment - ClickHouse is a globally distributed company and remote-friendly. We currently operate in over 25 countries.
• Healthcare - Employer contributions towards your healthcare.
• Equity in the company - Every new eligible team member who joins our company receives equity.
• Time off - Flexible time off in the US, generous entitlement in other countries.
• A USD$500 Home office setup if you’re a remote employee.
• Global Gatherings – We believe in the power of in-person connection and offer opportunities to engage with colleagues at company-wide offsites.

Culture - We All Shape It

As part of a rapidly scaling start-up, you will be instrumental in shaping our culture.

Are you interested in finding out more about our culture? Learn more about our values here. Check out our blog posts or follow us on LinkedIn to find out more about what’s happening at ClickHouse.

Equal Opportunity & Privacy

ClickHouse provides equal employment opportunities to all employees and applicants and prohibits discrimination and harassment of any type based on factors such as race, color, religion, age, sex, national origin, disability status, genetics, protected veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by federal, state or local laws.

Please see here for our Privacy Statement.

Compensation Range: €90K - €160K