Middle Full Stack Developer (Node.js/React)

We are a team of 120+ people building pdfFiller, an online platform for creating, editing, and signing PDF documents. pdfFiller supports over 10 million users monthly with unlimited storage, templates, and cross-platform integration.

• Experience with LangGraph or LangChain, agent orchestration, and state machines
• Experience with RAG and vector search (pgvector)
• Familiarity with SSE or other streaming protocols
• Experience with observability tools such as OpenTelemetry and the Grafana stack
• Experience with LLM evaluation, including eval datasets and LLM-as-judge
• Experience writing technical documentation (C4, ADR)

• Own features end to end, from requirements to production and post-release monitoring of edge cases
• Own the automated quality of what you ship, including unit and integration tests and eval cases for LLM behavior
• Treat prompt regressions, evals, and non-determinism as everyday engineering concerns
• Review code and documentation to keep the codebase consistent
• Take part in the duty rotation: monitor production and respond to incidents
• Propose improvements to processes, tooling, and legacy code as part of the team's ongoing modernization
• Build tool-calling, streaming, and RAG features with reliable real user usage