Full Stack Engineer, AI systems

ActAI; España; Presencial; EUR 60.000 - 90.000; Jornada completa

Descripción de la vacante

ActAI is seeking a Full Stack Engineer - AI Systems to build production-grade workflows, designing how agents operate, fail, recover, and deliver reliable value to users.

You will build end-to-end features across frontend, backend, and AI integrations, and design agent workflows that handle planning, tool use, failure, and recovery across multiple steps. Collaborate with ML, backend, and product teams to ship features with real-time AI interactions and low latency.

Formación

• Strong experience in full stack engineering (frontend + backend).
• Solid understanding of system design and API architecture.
• Experience with LLMs, RAG systems, or AI-powered applications.

Responsabilidades

• Build end-to-end product features across frontend, backend, and AI integrations.
• Design agent workflows that handle planning, tool use, failure, and recovery across multiple steps.
• Integrate LLMs, memory, and external tools into systems that behave reliably under real-world conditions.
• Design real-time AI interactions with streaming, partial results, and tight latency constraints.
• Improve system reliability, observability, and fallback mechanisms.
• Collaborate closely with ML, backend, and product teams to ship features end-to-end.
• Continuously iterate based on real usage and failure modes.

Conocimientos

Full stack engineering

API architecture

LLMs & AI apps

Ambiguity tolerance

Ownership

Fast-moving environments

Herramientas

Next.js

Python

Node.js

PyTorch

OpenAI/Anthropic LLMs

SQL

NoSQL

Docker

Descripción del empleo

There are over 5 billion users using basic applications today such email, notes, tasks, calendar and they're not AI-native. Our mission is to build proactive applications for anyone in the world, who are not used to complex prompting. We aim to bring intelligence to conversations, errands, organising and workflows, with minimal prompting.

Our product focuses on achieving high reliability for long-running workflows, persistent context, and real-world task completion. We believe products will greatly reduce hallucinations

Our objective is to organise anyone's life, allowing us all to spend time on valuable and meaningful things

Role

We are looking for a Full Stack Engineer - AI Systems to build the product layer that turns these capabilities into usable, production-grade workflows. This includes designing how agents operate, fail, recover, and deliver consistent value to users.

Focus

• Build end-to-end product features across frontend, backend, and AI integrations


• Design agent workflows that handle planning, tool use, failure, and recovery across multiple steps.


• Integrate LLMs, memory, and external tools into systems that behave reliably under real-world conditions


• Design real-time AI interactions with streaming, partial results, and tight latency constraints


• Improve system reliability, observability, and fallback mechanisms


• Collaborate closely with ML, backend, and product teams to ship features end-to-end


• Continuously iterate based on real usage and failure modes

Ideal Experiences

• Strong experience in full stack engineering (frontend + backend)


• Solid understanding of system design and API architecture


• Experience working with LLMs, RAG systems, or AI-powered applications


• Ability to handle ambiguity and make pragmatic engineering decisions


• Strong ownership - able to take features from idea to production


• Comfort working in fast-moving environments with evolving requirements

Outcomes

• Own and ship AI-native product features that move beyond chat into persistent, goal-driven workflows


• Design and deploy agent workflows that reliably complete multi-step tasks across tools and sessions


• Reduce latency and improve responsiveness of AI interactions while maintaining output quality


• Build robust fallback and recovery mechanisms for LLM and tool failures in production environments


• Improve the success rate and reliability of AI-driven workflows through iteration, evaluation, and monitoring


• Establish patterns and abstractions for integrating LLMs, memory, and external tools into scalable product systems


• Contribute to a product experience where AI feels proactive, consistent, and dependable over time


• Next.js


• Python


• NodeJs


• Pytorch


• OpenAI / Anthropic / open-source LLMs


• SQL & noSQL


• Docker

How We Work

The best products today in the world were built by small, world class teams. We are a high talent density and hands-on team. We make decisions collectively, move at rapid speed, striking a balance between shipping high quality work and learning. Joining our team requires the ability to bring structure, exercise judgment, and execute independently. Our goal is to put in hands of our users a truly magical product