Tree-Nation is the world's largest reforestation platform, connecting citizens and companies with verified planting projects across the globe. Since 2006, over 800,000 users and 30,000+ companies have planted more than 45 million trees through our platform, across 40+ active reforestation projects worldwide.
We combine technology and environmental impact to make reforestation simple, transparent, and scalable. Our goal is to plant 1 trillion trees by 2050 — and we are building the platform, the automation, and the systems to get there.
Tree-Nation has a platform, a database, running integrations, and active business units. The system exists — and it needs an engineer who can own a strategic piece of it. This is a new role created to bring dedicated backend ownership to a specific operational domain: designing its data models, service layer, and integration points from the inside out. We are not hiring someone to rewrite everything. We are hiring someone who diagnoses before they prescribe — and then builds things that last.
This role owns the backend architecture of a specific operational domain at Tree-Nation — either environmental operations (project evaluation, monitoring, impact data flows) or revenue operations (CRM architecture, B2B pipeline logic, integration monitoring). You'll work alongside a tech team of 3–5 engineers, reporting directly into the core of the company. Your job is to map what exists, identify where well-designed services can replace fragile or manual workflows, and then build and ship those services in production. If you also bring experience with AI tooling or agentic workflows, there is real opportunity to apply it here — but strong platform engineering comes first.
Our team spans many nationalities, backgrounds, and disciplines. What we share is not a background — it's a mindset. We take ownership without being asked. We don't back down from hard problems — we enjoy them. We iterate fast, we wear multiple hats, and we go beyond what our job description says when the mission needs it.
We fear one thing above all: the routine.
We believe people do their best work when they genuinely care about what they're building. We try to keep it that way.
We are investing heavily in automation and AI to scale our impact — and we expect everyone on the team to engage with those tools as a natural part of their work.
We are based in Barcelona and work primarily from the office, because the density of collaboration matters to us.
Map the operational flows of your domain — identifying what is manual, fragile, repeated, or ripe for automation — before proposing any solution.
Define system scope precisely: not "fix the pipeline" but "a service that qualifies inbound leads based on company size, integration type, and engagement signal, routing to human review when confidence is below threshold."
Design modular backend services with discrete inputs, business rules, and outputs — isolated, independently deployable, observable, and replaceable.
Model the data first: design database schemas as the operational backbone of your domain before writing application code.
Structure data flows between internal systems, the platform database, CRMs, billing tools, and external APIs.
Build and ship backend services and APIs in production, with clear orchestration logic and well-defined human control points.
Build full-stack when needed — from data model to API to the supervisor interface used to monitor and correct system behavior.
Prototype fast, then industrialize — using whatever stack solves the problem (we use TypeScript and modern backend frameworks, but we don't have a sacred stack).
Own observability and failure handling from day one, not as an afterthought.
Be the accountable engineer for your domain's architecture — contributing to how its KPIs are defined and ensuring every technical decision reflects its operational consequence.
Leverage AI and LLM-powered components where they are the right fit — with the ability to reason clearly about control, failure modes, latency constraints, and output validation.
Days 1–30 — Understand the system. Map your domain. Interview the people who currently run the workflows you will eventually systematize. Identify the three highest-leverage points for engineering intervention.
Days 30–60 — Design the architecture for the first service. Define data models, inputs, business rules, outputs, failure modes, and human control points. Align with the tech team and ship a first working version into production.
Days 60–90 — Iterate based on real usage. Define the KPIs for your domain with relevant stakeholders. Begin scoping the next system.
Required
Strong backend engineering background — you have designed, built, and shipped production systems end-to-end.
Deep database design thinking: you model data before you write code and understand how schema decisions propagate into downstream behavior.
Experience with modular service architecture — systems that are scoped, isolated, composable, and replaceable.
Solid system design instincts: APIs, state management, integration patterns, failure handling, and observability.
Tool-agnostic approach — you choose the right tool for the problem and are comfortable building custom when off-the-shelf doesn't fit.
You diagnose before you prescribe — the right solution starts with the right question, and you can sit with ambiguity long enough to understand a problem fully before proposing a fix.
You can translate a business process into a system design — and back — and you understand that a bad data model creates bad decisions downstream.
Comfortable talking to non-technical stakeholders, asking operational questions, and making system decisions that reflect business reality.
Based in Barcelona and comfortable working on-site.
Strong Advantage
Practical exposure to LLM integration: context management, prompt reliability, output validation, and latency constraints.
Experience with multi-agent workflows, automated pipelines, or agentic task orchestration.
You choose AI tooling when it is the right fit for the specific problem — not because it is the interesting choice.
Mindset
High ownership — you take initiative, but you also know when to listen first. Tree-Nation does things differently, and the best people here understand context before trying to change it.
Comfortable with direct, no-frills feedback — we value honesty over diplomacy.
Systems thinker — you see the whole before you optimize the part.
Resilient and self-motivated — your drive comes from the mission, not from your manager's approval.
Genuinely aligned with the mission — this is not just a job to you.
Compensation & Contract
Competitive base salary aligned with market and experience
Permanent contract
Benefits
Flexible Remuneration Card covering meals and transport
Gympass membership
Regular team-building events
Environment
On-site role in Barcelona — our offices are built around sustainability and designed to inspire
Direct technical ownership of a strategic domain in a global platform
A small team that builds seriously, without bureaucracy
Hands-on access to the latest AI tools and frontier technologies
Work with real environmental impact at scale
If you've read this far and something clicked — the mission, the way we work, the problems we're solving — we want to hear from you.
We don't hire based on pedigree. We hire based on how you think, what you've built, and whether you'll make the team sharper.
We're looking for people who make the team better. Come prove it.