Senior Backend Engineer - AI Integrations

Wiser Technology designs, builds, and scales complex software systems that power real-world impact. With 500+ engineers and over 25 years of experience in mission-critical environments, we help global organizations turn ambitious ideas into working solutions. Across Europe, MENA, and North America, we combine deep engineering expertise with AI and data to support leading companies in aerospace & defense, automotive, telecom & media, IT, and financial services.

We are looking for a Senior Backend Engineer to join a dedicated squad that turns AI capabilities into reliable, secure and scalable services for a large enterprise client. You will design, build and operate the backend services, APIs and integrations that connect LLMs and AI agents with the client's business systems and day-to-day workflows. You will work hands-on within an established engineering team and build reusable components that other products can adopt. The team sets technical direction; you own your services end to end and drive your work forward without close supervision.

Core Responsibilities:

• Backend Services & APIs: Design, build and maintain backend services, APIs and data models for AI-powered products and workflow automation.
• AI Integration: Integrate LLMs, AI agents and other AI services into application workflows.
• Systems Integration: Build and maintain integrations with the client's business systems and external services.
• Reliability: Build workflows and background processing that behave predictably when the systems they depend on are slow, fail or return the unexpected.
• AI Output Quality: Make sure AI output is checked before it reaches users or downstream systems, with a clear path to human review where it matters.
• Quality & Observability: Write automated tests, and make services observable in terms of reliability, output quality and running cost.
• Security: Implement authentication, authorization and data protection in line with agreed security standards.
• Delivery & Collaboration: Work with product, QA and DevOps colleagues from design to production, take part in code reviews, and document what you build.

Hard Requirements:

• 5+ years of backend software engineering experience.
• Production-level expertise in Python or TypeScript (Node.js), including API design, data modelling, SQL and automated testing.
• You have integrated LLMs or AI agents into production applications used by real users, beyond prototypes and tutorials, and handled what happens when their output is wrong or needs human review.
• You have built and maintained integrations with systems owned by other teams or vendors.
• You have built and operated backend workflows in production, diagnosed issues in live systems, and kept performance and running costs in check.
• You have owned work end to end with little supervision, from clarifying loose requirements to unblocking yourself across teams and vendors and seeing it through to production.
• You work well within an established team, document what you build, and communicate clearly in English.

Preferred:

• Experience setting up automated evaluation for AI features, beyond manual spot checks.
• Experience with durable workflow engines for long-running, multi-step processes.
• Experience building agentic workflows with LangChain/LangGraph or similar frameworks.
• Experience building shared or multi-tenant services that several products or teams depend on.
• Experience with media or content platforms, such as content management or digital asset systems.
• Experience delivering highly compliant enterprise software, including data protection requirements such as GDPR.

WHAT'S IN IT FOR YOU:

Culture & Development:

• Friendly Environment: We take pride in our culture, and we love spending time together.
• Team Spirit: Be part of a supportive team that uplifts each other.
• Mentorship and coaching. Our colleagues are experts in their field, and you can expect to have a strong team to rely on.
• Personalized Development Program: We realize one size doesn't fit all, so you get an individual development plan tailored specifically to your career aspirations.

Social Benefits:

• A Suite of Perks: Additional health insurance, referral bonus, and more.
• Work Flexibility: Embrace flexible working hours and a hybrid work model.
• Multiple Office Locations: in Sofia, Plovdiv, Stara Zagora, and Nis, you choose where you would like to work.
• Community and Connections: Engage in exciting social events and team initiatives.

Wiser, We Have The Code®