Based in Brazil · Working with US & EU teams
I’m a senior backend engineer with 10+ years in fintech, HR tech, media and e-commerce. My focus is correctness at scale — systems where a quiet bug means lost money or trust, not a cosmetic defect.
Production systems at Deel · Nubank · Imgur · eBay · CVC
SERVICES
Every engagement starts with your problem, not a tech stack. Here’s what I take on, and where I learned to do it.
01 · PAYMENTS
Refunds, settlement and balances that finance has stopped trusting.
I build payment backends that are correct first and auditable by default — idempotent, reconciled, and safe to retry across asynchronous, distributed services.
For: Fintechs, marketplaces, SaaS billing
02 · DATA AT SCALE
Your data outgrew the job that processes it.
I design pipelines that stay fast and correct as volume grows — real-time processing, safe re-runs, and changes validated in production before they replace what works.
For: Data-heavy products & platforms
03 · INTEGRATIONS
Every new customer needs another integration, and each one breaks differently.
I build integration layers with clear contracts between your platform and third-party systems, so onboarding a customer stops being a custom project.
For: B2B SaaS & platforms
04 · MODERNIZATION
The old stack is expensive to run and scary to change.
I move services to a better language or infrastructure piece by piece, with production traffic flowing the whole time — and the cost savings to show for it.
For: Teams carrying legacy code or infra
ABOUT
I’m Herycklys, a backend engineer from São Paulo, Brazil. I’ve spent my career on the parts of big products that have to be right: payments, trust and safety, integrations and the infrastructure underneath them.
Outside of work: reading, long runs, and occasionally shipping personal projects that scratch an itch.
Integrations, the marketplace app and its migration to new infrastructure; now on AI evaluation tooling.
HR Tech · Integrations · AI
Refund and settlement flows on NuPay for 200+ merchants, the merchant KYC onboarding service, and internal AI tooling.
Fintech · Payments · Clojure
Real-time trust-and-safety pipelines, media transcoding at 10TB+/day, sitemaps over 6B+ entries, and the move from PHP to Go and EC2 to Kubernetes.
Media · Go · Kubernetes
Internal SEO tooling that cut operational errors, and the team that grew to own eBay’s SEO tooling experience.
E-commerce · SEO
New checkout and the BFF to the internal payment provider, as part of a redesign that improved conversion.
Travel · Checkout · Next.js
2015 — 2019 · Earlier: technical lead at SourcerDigital, plus full-stack roles at Kenoby, Sciensa, Aktie Now and Docpix.
HOW I WORK
Step 1 · Free · 30 min
You describe the problem; I tell you honestly whether I’m the right person for it.
Step 2 · Fixed scope
I dig into the system and come back with the target outcome, the approach and a fixed price.
Step 3 · Ship safely
Run old and new side by side before cutover, leave documentation your team can own, and show the before/after.
READY TO START?