Ruan Vieira · Full Stack Developer in São Paulo

available for new projects

I'm Ruan Vieira, a full stack developer from São Paulo. My path in programming started in 2019, when I wrote Lua scripts for FiveM servers. What began as curiosity quickly became a profession. In 2021, I founded Simplify Code to turn ideas and real needs into digital solutions.

Since then, I've worked on projects across different industries, from SaaS platforms and marketplaces to management systems, integrations, APIs and web applications. I've also built my own products, like Crie Club, BoEstudar and TechMoney. These experiences broadened my view of technology, product and business. For me, development goes far beyond writing code: I like understanding the problem, taking part in decisions and building solutions that make a difference for the people who use them. After delivery, I keep following the projects, listening to people and looking for ways to improve them. I want to use technology to solve real problems, create good experiences and deliver results that make sense for people and businesses.

Let's talk See what I built

📍 São Paulo, Brazil

How I work

Every project has its own context. My starting point is understanding the problem and building the solution together with the people who know the day-to-day.

01
Understand
I talk to the people involved to understand their routine, their difficulties and the expected result. That way, the solution starts from the real problem, not just the initial request.
02
Define the path
I organize the needs into clear stages and priorities. We agree on what will be done, how the solution should work and what will show that it's working.
03
Build and evolve
I build the solution with attention to experience, reliability and security. After delivery, I follow usage and results to guide the next adjustments.

Projects and results

Every project starts with a need. Here I show the context, the product decisions and what was built.

MalhaCÃO

E-commerce · freelance · 2026

The store had visitors, ~~but few of them turned into purchases.~~

Without increasing the marketing budget, improvements to the shopping experience made the same number of visits generate 3.8 times more purchases.

per 1,000 visits, with the same traffic volume3.8× more purchases per visit

0.1%

1 purchasebefore

0.38%

3.8 purchasesafter

Store and pages

Landing page rebuilt from scratch, designed first for visitors on mobile
Product page redesigned to lead people to the purchase
Store components rebuilt and improved, with the same standard on every page

Conversion and trust

Conversion optimization (CRO) at every step up to checkout
A more professional look that builds trust with first-time buyers

Search and speed

Technical SEO so the store shows up better on Google
A faster site, optimized to load well on mobile
Simpler navigation and search

Shopify
Liquid
SEO
CRO

previous platform

about 4 in 10

own platform

6.8%

purchases that turned into refunds

CrieClub

Digital products marketplace · 2026

The product had demand, ~~but many customers asked for refunds.~~

I built a platform of their own to give the operation more control and create a buying experience that matches the product's value. The refund rate dropped from about 4 in 10 purchases to 6.8%.

from sign-up to first purchase (median): ~6 min
buy within an hour of signing up: 69%
of buyers come back to buy again: 19%

Own checkout

Pix and card with Mercado Pago and Stripe, no longer tied to a third-party platform
Migration from the old platform, keeping the history of past buyers
Coupons and automatic revenue split between creator and collaborators

Fewer refunds and less fraud

Proof of every purchase: policy acceptance, device and checkout location stored to answer refunds and chargebacks
3D Secure on cards and refund requests handled inside the platform

Delivery and community

Protected downloads with S3 and CloudFront
Reviews and favorites that give products a community feel
Sign in with Google and Discord

Tracking

Own analytics for visits, buy-button clicks and UTM links
Webhooks so creators get every sale in their own systems

Next.js
MongoDB · Prisma
Mercado Pago
Stripe
S3 · CloudFront
OAuth

Community automation

Sales and management bots · 2021 →

Sales and support depended on manual tasks, ~~which delayed deliveries and overloaded the people in charge.~~

communities: +100
users: +500K
sales: +21K

Sales and delivery

Hands-off sales: Mercado Pago checkout and instant delivery, without the owner having to be online
Access granted automatically: after a purchase, the bot shares the product folder on Google Drive or Dropbox with the buyer, and removes access if the purchase is canceled

Community

Community management: roles and members organized by the bot itself
Support and engagement: support tickets, coupons, giveaways and a reputation system

Control

Full history: every sale, delivery, payment and staff action is logged with date and person responsible, for later review and compliance
Web dashboard for the owner to follow sales, members and support

TypeScript
Node.js
discord.js
MongoDB
Zod
Mercado Pago
Google Drive
Dropbox

Chama Garçom

Restaurants · 2025–2026

Customers needed to call the waiter, ~~but they weren't always served in time.~~

calls handled: +14,800
for the waiter to respond: ~2 min
table rating: 4.6★

At the table

QR code on the table and real-time waiter calls
Menu and orders from the customer's phone
Service rating at the end, which produces the 4.6 score

For the staff

Waiter app on the phone, with push notifications
Manager dashboard: tables, waiters, calls, orders and statistics
Desktop POS in Electron, integrated with the Stone card machine

For the business

Paid plan subscription through Mercado Pago: 47 restaurants signed up, 19 paying
WhatsApp bot for support and notices
Platform dashboard: clients, subscriptions, blog, tutorials and how each restaurant found the product

Next.js
React Native
Electron
Stone POS
Mercado Pago
WhatsApp

Grupos Promoções

Deal automation · 2026

Finding good deals meant following several sources, ~~and many deals expired before they could be shared.~~

products analyzed: ~589K
deals found: 4,657
average discount: 43%

Sourcing

17 sources scanned nonstop for new deals
141k price history points to catch fake discounts

Curation

A score for every deal, with reasons and penalties shown on the dashboard
Checked before posting: suspicious or expired deals are blocked

Publishing

Telegram, Discord, WhatsApp and X, each channel with its own rules: stores, price range, keywords, quiet hours and hourly limit
Affiliate links generated automatically, with 2k clicks in 2 months

Product

Public marketplace and personalized alerts for each person
Multi-tenant and white-label, with commercial campaigns and analytics

Python
FastAPI
PostgreSQL
Next.js
Docker

ScienceVet

Veterinary research · 2025–2026

Study tracking depended on spreadsheets, ~~with no clear history of stages and responsibilities.~~

Studies

Every study with versions, history and files, and the ethics committee (CEUA) stages tracked in the system
Dashboard with the progress of every study

Animals and supplies

Animals tracked by species, breed, farm and history
Inventory with stock in, stock out, returns and quality control

Compliance

Every action logged with date and person responsible
Reports on quality control and sample shipping that meet the Ministry of Agriculture requirements, in PDF and Excel
Roles and permissions per user, including third parties

Next.js
Prisma
PostgreSQL
jsPDF
ExcelJS

PlayHard

Gaming events · Rondônia, Brazil

Sign-ups, payments and consumption were tracked on paper, ~~which made organizing and reconciling the event harder.~~

players: 686
events: 21
tabs: 448

Events

Sign-ups, duos and reservations for every tournament
Organizer dashboard with teams, donations and event numbers

Payments

Sign-ups and donations via Pix with Mercado Pago
Cancellations and refunds handled in the system, no spreadsheets

Comanda

Bar consumption tracking during the event
Per-customer checkout, knowing who paid for what

Next.js
Prisma
MongoDB
Mercado Pago
Pix

Quadraz

Sports court booking and management · lead developer · 2025–2026

The product rules were complex, ~~and users struggled to find what they needed.~~

For players

Search and compare courts with photos, prices and schedules in one place
Quadraz Play: organize and join tournaments and games
SEO with a sitemap and share images on every page

For managers

Sports centers and courts listed with surface, roof, lighting and amenities
Users and permissions, ratings, blog and newsletter

As lead developer

Own API in Node.js with Express and Prisma, from back end to screens
Requirements turned into flows that are easy to follow, with the site and the dashboard on the same standard

Next.js
Node.js · Express
Prisma
UI/UX
Design system

Landing pages

Doctors, studios and professionals

The sites generated leads, ~~but there wasn't enough data to understand where they came from and what worked.~~

Lead capture and tracking

Client dashboard: leads, campaigns, users, audit logs and Excel and PDF exports
Source tracking: UTM links per campaign, to know which ad or post brought in each lead
Own analytics, only with consent and without storing IPs: visits, pages, devices and where the audience comes from

Search: SEO, GEO and AEO

Technical SEO: sitemap, robots, share images and one page per specialty
Structured data (JSON-LD) for person, site and procedures, so Google and AI tools understand who the professional is and what they do
FAQ written to answer real questions, the way search engines and AI assistants read them

Speed and media

Performance: cover image from 3.9 MB to 67 KB and a layout that stopped jumping on mobile (CLS from 0.66 to 0)
Cloudflare Stream: videos converted automatically and played at adaptive quality, without stuttering on mobile
Cloudflare R2: file library with chunked uploads straight from the browser, never passing through the server

Contact

Appointment booking right on the site
Validated forms, with leads landing straight in the client's inbox

Next.js
Prisma · MongoDB
Cloudflare R2
Cloudflare Stream
hls.js
Zod
SMTP

my own products

Products I conceived and built. In them, I follow every stage: from the initial problem to product decisions and continuous evolution.

BoEstudar

AI study platform

AI-generated flashcards, quizzes and mind maps
Schedule, roadmap and audiobooks
Achievements, friends and gamification to keep the habit
Paid plans with Mercado Pago and automatic payment reconciliation

Next.js
IA
MongoDB
Mercado Pago
Playwright

TechMoney

Personal finance

Analytics dashboard for income, expenses and investments
Goals, recurring bills and multiple banks
Social login and detailed reports

Next.js
MongoDB
OAuth

Technologies and experience

Tools I choose according to the problem, the team and the context of each product.

the ones I use most

Languages

I use TypeScript in most projects and Python when the solution calls for automation or data processing.

JavaScript
TypeScript
Python
Lua

Front-end

I build fast, accessible interfaces, with multi-language support and animations that help explain the experience.

React
Next.js
Tailwind
Framer Motion
i18n (next-intl)
Three.js
hls.js

Back-end and data

I build APIs and integrations, organize data and implement authentication, validation and logging to make operations predictable.

Zod
Prisma
MongoDB
NextAuth/OAuth
Node / Express
Socket.io
PostgreSQL
FastAPI

Mobile and desktop

I build mobile and desktop experiences connected to the same product, like the Chama Garçom service app and POS.

React Native
Electron

Payments and integrations

I integrate payments, support channels and third-party services to connect the digital experience to business operations.

discord.js
Mercado Pago
WhatsApp
Stripe
Stone POS
Google Drive
Dropbox

Infra and quality

I take care of deploying and running the systems, with cloud storage and tests to reduce problems when things change.

AWS S3
Jest / Vitest
Docker
VPS + Nginx
Playwright
Cloudflare R2
Cloudflare Stream

Education and courses

Systems Analysis and DevelopmentFIAP · 2020–2021
Data VisualizationFIAP certificate
Django Web FrameworkFIAP certificate
Business Strategies and ModelsFIAP certificate

Studying and exploring

Cybersecurity

I study through CTFs and hands-on labs. I bring that knowledge into security decisions on my projects, like auditing, abuse protection and fraud prevention.

AI applied to products

I build AI features in BoEstudar and explore agents to support my work, always reviewing what is generated before using it.

Motion and 3D on the web

I explore Three.js and Framer Motion to create interactions that guide and give context, beyond improving the visual presentation.

What drives me

I like seeing a solution improve people's routine and help a business move forward.

01
Behind every system, there's an operation that needs to work.
Restaurants, stores, labs and events depend on well-organized processes. Understanding that context helps create tools that support the work and remove obstacles from the day-to-day.
02
Following up on the work is part of the delivery.
3,934
commits since 2023
749
days with code
59
repositories
Each square represents one hour of the week; the intensity shows the recorded activity.
03
Security is part of the experience.
Activity logs, abuse protection and fraud prevention help take care of operations and data. That attention matters in projects of any size.

A good solution also prevents problems nobody ever gets to notice.

Frequently asked questions

What do you do?

I'm Ruan Vieira, a full stack developer in São Paulo. I work on digital products, web systems, apps and automations. I try to understand the problem and the business context before defining the solution. I founded Simplify Code in 2021.

How long have you been coding?

I've been coding since 2019. In 2021, I founded Simplify Code, through which I build solutions for businesses across different industries.

What results have you delivered?

In projects I followed, a store's conversion went from 0.1% to 0.38%, a marketplace's refunds dropped from about 4 in 10 purchases to 6.8%, and a product for restaurants has logged more than 14,800 handled calls.

Which technologies do you work with?

I work mainly with JavaScript, TypeScript, React, Zod, Prisma, Next.js, Tailwind. I choose technologies based on the product's needs, including React and Next.js for interfaces, React Native for apps and Node.js with Prisma, MongoDB or PostgreSQL on the back end.

Do you work with companies and freelance?

Yes. I take on projects through Simplify Code and also as a freelancer, working with companies and teams across different industries.

How does a project with you work?

I start by understanding the problem, the people involved and the expected result. Then I organize scope and priorities, build the solution and follow its use to identify improvements after delivery.

Do you take care of security?

I include security measures according to each product's context, like audit logs, rate limiting and fraud prevention. I also study cybersecurity through CTFs and hands-on labs.

Do you work remotely?

Yes. I work remotely and I'm also open to on-site or hybrid offers.

How do I reach you?

You can reach me on WhatsApp or by email, through the links at the bottom of the page. I usually reply within one business day.