Hi! I'm Mathi Fonseca

Senior Staff Engineer, Fintech
@ Wolt + DoorDash
15 years building payment systems at scale,
now driving AI-native engineering.

Mathias Fonseca smiling with a rainbow in the background

Lead Architect

Proven track record of building scalable, high-performance systems, and leading cross-functional teams.

Payments Expert

Extensive experience in designing, scaling, and optimizing payment systems globally.

Strategy Minded

Strong ability to align technical solutions with business goals, collaborating with product management and sales teams.

Knowledge Sharer

Passionate about teaching, sharing knowledge, conducting workshops, and fostering continuous learning within teams. Basically, I always have a whiteboard near me.

Problem Solver

Dedicated to solving complex challenges with a mix of curiosity, creativity, and a pragmatic approach.

AI-Native Builder

Driving how engineering teams adopt AI — raising developer velocity and moving from AI-assisted to genuinely AI-native ways of working.

I design and build payment systems that operate at the intersection of product, engineering, and scale. Over 15 years I've worked across the full stack of payments: PSP integrations, orchestration, fraud prevention, checkout optimisation, payouts, and compliance — across Latin America, Europe, the Middle East, and Asia.

At PedidosYa, I led payments and fraud engineering across the $2.5B GMV platform spanning 15 countries — one of the highest-fraud payment environments in the world. Imagine how being on-call was like!

At Delivery Hero, I joined the Global Fintech team when it was 3 people and helped grow it to 100+ people in Berlin HQ and many more at regional entities, powering payment infrastructure for 50+ countries and $40B in annual GMV.

At Payrails, I was the first employee — designing the core architecture from scratch, growing the company to 100+ people across 9 teams, and building the product that enterprise merchants rely on for their entire payment stack.

Today I'm a Senior Staff Engineer in Fintech at Wolt — part of DoorDash's global Money organization spanning Wolt, Deliveroo, and DoorDash, one of the world's largest local-commerce platforms. Alongside the payments work, I'm one of the people driving how our engineering org adopts AI: raising developer velocity, serving as an AI Ambassador, and pushing toward genuinely AI-native engineering rather than AI-as-autocomplete.

I move fluidly between whiteboard and codebase. I've led teams, shaped roadmaps, and written the actual code. I believe the best systems are built by engineers who understand the business, not just the technology.

→ Currently focused on payments at scale and building AI-native engineering practices in fintech.