Hi, I'm
Luan Rabelo
Senior Software Engineer · .NET / C#
Senior engineer at NTT DATA, mostly backend, mostly C#. Before that I took a checkout from 1K to 16K requests per second. Outside of work I write compilers in assembly and send patches to LLVM.
Tools I work with
A bit about me
I'm Luan, a software engineer from Alexânia, Goiás. I've been building software since 2022, mostly C# and .NET on the backend, plus enough React and Next.js to build the screens that sit on top of it.
Today I'm a senior software engineer at NTT DATA. Before that I spent two years at TMB Educação on the checkout and payments side: PIX and boleto through Asaas, fraud checks with Serasa and ClearSale, ID documents read with Azure AI Vision, and a fair amount of Redis work to get the checkout from 1K to 16K requests per second.
I like knowing what's going on under the abstraction I'm using. That's how I ended up writing a C compiler in x86-64 assembly, building a bank on Orleans to see how far the actor model goes, and getting two patches merged into Clang.
Where I've worked
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NTT DATA Europe & Latam
Senior Software Engineer
-
TMB Educação
Software Engineer (.NET / C#)
- Rebuilt the checkout on .NET, Redis and PostgreSQL and took it from 1K to 16K requests per second. CEP lookup, installments shown upfront, PIX and boleto through Asaas, and the loan contract signed inside the purchase flow.
- Fraud checks at purchase time: Serasa, ClearSale, and ID documents read with Azure AI Vision (OCR) and matched against Receita Federal records.
- Built the portal course creators use to manage their products, in Next.js on top of a .NET and EF Core API.
- Moved slow work off the request path with Azure Service Bus queues and Azure Functions. Set up the CI/CD pipelines in Azure DevOps.
- Also tuned PostgreSQL queries, worked on loan settlement and amortization, and built a few internal screens in ScriptCase.
C#.NETRedisPostgreSQLAzureNext.js -
Explorernet
Software Developer
- Field app for the ISP’s technicians in React and Next.js: geolocation, automatic router provisioning, and a connection check before a service order can be closed.
- Credit screening for the sales team through the Serasa API, hooked into lead registration.
- WhatsApp sales bot on N8N connected to the CRM. Conversion went up 30%.
- Salesforce admin and developer: custom components for plan changes, support tickets and CRM automation.
ReactNext.jsN8NSalesforce -
Divtech
C# Developer / Systems Analyst
- New features on IPMA, an ASP.NET Core system used in public-sector operations.
- File manager in Blazor and Razor Pages with role-based access control.
- Rewrote slow SQL Server queries. The worst ones got up to 100x faster.
- Client dashboards and automated generation of PDF certificates.
C#ASP.NET CoreBlazorSQL Server -
Centro Universitário FAM
B.Sc. in Computer Science
Things I've built
ActorBank
A small bank built on Microsoft Orleans to see how far the actor model goes. Each account is a grain that handles one message at a time, so there are no locks and no lost updates. Transfers are ACID across both accounts, the ledger is append-only, and k6 load tests check that money is never created or lost.
uOpCC
A C compiler written from scratch in x86-64 assembly. It handles a real subset of C (functions, recursion, block scopes, if/while, every arithmetic and bitwise operator) and emits fasm2 code that becomes an ELF64 binary. No linker, no libc.
LLVM / Clang
Two patches merged upstream. One makes Clang widen enum values that overflow a _BitInt type, the way C23 says it should and GCC already did. The other fixes broken HTML nesting in the Clang Static Analyzer reports. Both went through review by the maintainers.
FASM2 Studio
VS Code extension for fasm2/fasmg that also understands classic fasm 1. Completion, hover docs, go-to-definition and rename across the whole project, errors from the real assembler while you type, and build, run and debug through gdb. Works on Linux, macOS and Windows.
Formaster
Browser extension that fills forms with fake but valid data. You click the fields once, pick a generator for each one (CPF, CNPJ, address, credit card, or your own JavaScript), and it saves a script for that site. From then on it’s one click. Useful for testing signup and checkout flows.
Let's connect
Open to new opportunities
I'm at NTT DATA today, but I'm still listening. If you're hiring for backend or .NET work, or just want to talk about Orleans, compilers or assembly, send me an email.
rd1qys@gmail.com