Cala is looking for a Backend Engineer with 4+ years of experience to build the systems behind AI-driven information verification at scale
They’re building a verified knowledge graph for AI agents, and they’re looking for someone who is strong in backend work (Python, APIs, distributed systems) and also enjoys working on data, infrastructure and applied AI.
Hybrid in Barcelona (3 days/week at their new office on Gran Via)
Perks: flexible benefits for transport, meals and health insurance, plus a hiring process built on conversations with no coding tests
It’s a good opportunity for someone who likes owning systems end to end and wants to join an early-stage AI company.
Recently, Cala AI was named by Creandum to their #EuroSeed50 list - highlighting the most promising early-stage startups in Europe - an honor that reflects the strong belief in our mission and team. We are now growing our engineering team with an experienced Backend Engineer who enjoys working across boundaries - backend, data, infrastructure, and applied AI.
We’re looking for an experienced backend engineer with depth.
You’ll come from a Backend Engineering background - Python, APIs, distributed systems - but what matters most is your motivation to build across layers and solve complex problems end-to-end. Backend is your anchor, but this is a high-impact engineering position for someone who enjoys working with multiple parts of the system rather than in a narrow specialization.
You’ll work closely with our core team to design, build,



and scale the backend systems that power large-scale AI-driven information verification and representation.
Design and build backend services using Python (FastAPI)
Architect data storage and retrieval systems using SQL and NoSQL technologies (Postgres, Redis, Cassandra, graph databases)
Work with cloud infrastructure on AWS and containerized environments (Kubernetes)
Experiment with emerging AI engineering tooling (coding agents, MCP ecosystems, etc.)
Contribute to a culture of clean, pragmatic, high-quality engineering
Python
FastAPI or similar frameworks
AWS
SQL and NoSQL databases (Postgres, Redis; Cassandra or graph databases are a plus)
DevOps practices
4+ years of hands-on backend engineering experience, with real depth - you’ve gone deep, not wide and shallow
~ Builders at heart: hackathons, side projects, open-source contributions, active GitHub are all highly appreciated
~ Curious about how things work end-to-end, including the parts adjacent to your own - infrastructure, data, the systems your code runs on
~ C1+ level in either English or Spanish (fluency in either is acceptable)

We strongly encourage applications from women, underrepresented groups in tech, and individuals from non-traditional or less represented backgrounds. New office on Gran Via (Barcelona), with a full dedicated space for Cala AI
Adaptable benefits covering transport, meals, and health insurance
Join at an early stage and help shape both technology and culture
Hiring Process – Conversation-Based (No Coding Tests)
Initial chat with team member focused on experience and projects
Cultural fit conversation with CEO

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