Senior Backend Engineer - AI platform

Our unique data and solutions empower thousands of customers globally, including industry giants like Google, eBay, and Adidas, to make game-changing decisions that drive their digital strategies.

Why is this role so important at Similarweb?

AI is transforming how Similarweb operates, but scaling it requires a robust, production-grade foundation. Instead of every product and internal engineering team reinventing infrastructure, we are building a centralized, high-throughput AI Platform.

As a Senior Backend Engineer (AI Platform), you will design and implement the resilient core services powering our AI ecosystem: high-concurrency agent runtimes, distributed tool and data pipelines, low-latency model gateways, and real-time evaluation and observability systems. Your internal customers are teams across the whole company, including engineers, data scientists, back office and product teams - your systems will turn AI prototypes into scalable, fault-tolerant production services deployed across Similarweb. You will not build isolated AI features; you will build the scalable platform layer that handles state management, routing, and system reliability for dozens of high-throughput AI workflows.

What will you be doing?

• Core Systems Design: Architect and build the high-availability agent platform - focusing on distributed orchestration, state/memory persistence layer performance, event-driven execution, and a high-performance Python SDK.
• API & Integration Architecture: Design and operate scalable tool and connector services, including standardized Model Context Protocol (MCP) servers, gRPC/REST endpoints, and secure wrappers for Similarweb data stores, internal microservices, and external APIs.
• Low-Latency Model Infrastructure: Build low-latency model gateways, connection pooling, automated failover routing, semantic caching layers, and rate-limiting infrastructure.
• Security & Governance: Implement zero-trust security patterns at the platform layer: fine-grained access control (RBAC/ABAC), isolated data boundaries, PII detection pipelines, and high-throughput audit logging.
• Reliability & Performance Engineering: Optimize distributed execution to ensure strict SLA compliance, minimizing end-to-end latency and compute costs while ensuring system observability through distributed tracing and custom metrics.

This is the perfect job for someone who brings:

• 5+ years of software engineering experience in backend development, with advanced proficiency in Python and backend system architecture.
• Strong system design background: Experience building asynchronous microservices, REST/gRPC APIs, distributed state management, containers, and CI/CD pipelines.
• AI Framework Engineering: Hands-on experience building or extending agentic runtime frameworks (LangGraph, LangChain).
• Production Operations: Solid grounding in database architecture (SQL, NoSQL, Vector Databases), caching strategies (Redis), and event-driven messaging (Kafka/RabbitMQ).
• Cross-functional Collaboration: Proven ability to design clear API contracts and developer-facing platform tooling for other engineering teams.

Preferred Skills:

• Infrastructure & Cloud: Hands-on experience with AWS, Kubernetes, Terraform/CloudFormation, and modern cloud-native deployment patterns.
• LLMOps & System Optimization: Expertise in cost and latency optimization, dynamic model routing, load balancing, and capacity planning for high-volume LLM workloads.
• Data Engineering & RAG: Experience designing scalable retrieval-augmented generation (RAG) pipelines over large-scale, heterogeneous data lakes.
• Observability & Monitoring: Experience setting up distributed tracing and custom APM dashboards for backend services.

Why you’ll love being a Similarwebber:

• Impact : Work with the world’s leading digital intelligence platform and make a real difference.
• Innovation : Bring your ideas forward - we empower you to drive change.
• Hybrid work model: 3 days in our office and 2 days working from home.
• Our Office: Modern space in Prague’s DOCK IN area, stocked with snacks, drinks (we're big fans of kombucha), fruit and lunches on Tuedays.
• Benefits: 5 weeks of vacation, birthday day off, 3 sick days, or Multisport
• Top-tier Hardware : MacBook Pro M5, dual monitors, standing desks.
• Team Events : Regular team-building activities, monthly birthday celebrations with cakes and drinks, baking Thursdays and happy hours.
• Equity : Share in Similarweb’s success.
• Career Growth : Explore any path - leadership, switching teams, or upskilling through coaching and learning programs.