Senior Software Engineer (Backend)

Atlas Systems; São Paulo; Sur place; BRL 300 000 - 500 000; Plein temps

Avantages offerts par ce poste

Stock options

Benefits matched in cash, Wellhub, PJ-

Paid time off under PJ contract

Résumé du poste

Zatlas, a payments automation platform for hospitality, is hiring a Senior Backend Engineer in São Paulo to own backend systems end-to-end—from design to production. You will work across Payments, Integrations and Architecture in a small, all-senior team with direct access to founders.

You will ship scalable services in Java/Kotlin on the JVM, with Spring, PostgreSQL and AWS, while maintaining quality, security and observability. Office-based with Tue/Thu in person.

Qualifications

• 6+ years building backend systems in production.
• Solid experience with Java or Kotlin on the JVM, ideally with Spring, and with PostgreSQL.
• Strong CS fundamentals: data structures, algorithmic complexity and distributed systems design.
• Hands-on experience with integrations with external partners (APIs, webhooks, async messaging).
• Pragmatism: simple solutions that work and ship within a timebox.
• Ownership: shipped production features and been accountable.
• Clear, concise communication in writing and conversation; advanced English.

Responsabilités

• Design, build and run scalable, resilient backend services that move real money for hotel clients.
• Correctness in financial flows: charging, routing across acquirers, reconciliation, settlements and disputes.
• Build and maintain integrations with external partners: OTAs, channel managers, PMSs, acquirers and payment processors.
• Work directly with partners' technical teams to get integrations live and keep them healthy.
• Take part in architecture decisions and maintain code quality, security and observability.
• Mentor teammates and help raise the engineering bar as the team grows.

Connaissances

Java/Kotlin

Spring

PostgreSQL

Distributed systems

APIs & integrations

On-call ownership

English

Outils

AWS

Datadog

Description du poste

Zatlas is the payments automation platform for hospitality. We sit between hotels, their OTA partners and their acquirers, and recover the revenue that falls through the cracks. We are hiring a Senior Backend Engineer in São Paulo to build the payment and integration systems that hotels rely on to collect their revenue.

Our stack

Backend: Kotlin and Java with Spring

Database: PostgreSQL

Cloud: AWS

Observability: Datadog

Frontend: React (fullstack experience is a plus, not required)

Tooling:

AI-assisted development (e.g., Claude Code) is part of our daily workflow

Kotlin is not required: strong Java engineers pick it up fast.

Why this role, and why now

Zatlas recovers the revenue that falls through the cracks between hotels, their OTA partners and their acquirers: virtual credit cards (VCCs) that never get charged, cancellation and no-show fees that go uncollected, and payment methods that turn out to be invalid. Our clients include some of the largest hotel groups in Latin America, and we are expanding globally.

We are backed by Kaszek and Picus Capital and have grown 5x year over year. You will join as a senior individual contributor who owns backend systems end to end, from design to production. You are not tied to one squad: you will work across Integrations and Finance as priorities shift, in a small, all-senior team where every person has outsized impact.

What you will own

1. Payments and financial flows

• Design, build and run scalable, resilient backend services that move real money for our hotel clients.
• Correctness in financial flows: charging, routing across acquirers, reconciliation, settlements and disputes.

2. Partner integrations

• Build and maintain integrations with external partners: OTAs, channel managers, PMSs, acquirers and payment processors.
• Work directly with partners' technical teams to get integrations live and keep them healthy.

3. Architecture and engineering quality

• Take part in architecture decisions, choosing the simple, boring solution first and adding complexity only when the problem demands it.
• Keep code quality, performance, security and observability high, including on-call ownership of what you ship.

4. Product and team

• Work with Product, Operations and Account Management to understand the hotel's problem before writing code.
• Mentor teammates and help raise the engineering bar as the team grows.

Who we are looking for

We hire senior engineers who ship pragmatically and own outcomes, not just tickets.

MUST HAVE

• 6+ years building backend systems in production, currently at a senior level.
• Solid experience with Java or Kotlin on the JVM, ideally with Spring, and with relational databases (PostgreSQL or similar).
• Strong CS fundamentals: data structures, algorithmic complexity and distributed systems design.
• Hands-on experience with integrations with external partners (APIs, webhooks, async messaging) and with the failure modes that come with them.
• Pragmatism. You pick the simplest solution that works, avoid over-engineering, and ship within a timebox.
• Ownership. You have taken something from zero to production and been accountable for it.
• Clear, concise communication, in writing and in conversation, including disagreeing with a real argument.
• Advanced or fluent English.

STRONG PLUS

• Payments, fintech or high-scale platforms (e.g., Mercado Livre / Mercado Pago, Nubank, Stone, PagBank, PicPay, iFood).
• Growth inside the same company (promotions, broader scope) and tenure that shows commitment.
• Startups or tech-driven companies where you built before you scaled.
• Intermediate Spanish (many of our clients are in Mexico).
• Interest in growing into technical leadership over time.
• Frontend experience with React.

PROBABLY NOT FOR YOU IF

• You want to stay in one narrow area. Here you move across Integrations and Finance as priorities shift.
• You reach for the most sophisticated architecture first, rather than the simplest thing that works.
• You prefer to hand off what you ship rather than own it in production, on-call included.
• You are looking for a fully remote role. We are together in the office every Tuesday and Thursday.

How we work

We work hard and keep it sustainable: focused days, rare weekends, and 2-month OKR cycles that make priorities and impact visible. The engineering team is flat and all-senior, with direct access to the founders. We pick the simple, boring solution first, ship within a timebox, and own what we build all the way to production.

Our hiring process

1. People Interview
2. Technical Interview
3. Manager's Interview
4. Found'er's Meeting
5. Reference Check

What we offer

• Stock options: real ownership in a company growing 5x year over year.
• Benefits matched in cash, Wellhub, and paid time off under PJ contract.
• A flat, all-senior engineering team with direct access to the founders.
• Real problems at scale: millions of transactions across multiple acquirers and the largest hotel groups in LATAM.
• Visible impact from week one, and room to grow into technical leadership.