Hello! Im Matheus Mendes and im a software engineer

Things I've worked on

Midjourney

Making images look good

Work

Dema

Analytics platform for E-commerce

Work

jefftube

TypeScript

Sideproject

vercel-ui

Design library inspired by Vercels design system

TypeScript

Sideproject

css-only-rubiks-cube

A spinning Rubik's Cube with functionality all made with CSS only

CSS

Sideproject

lucio

TLDR; Leetcode and CSS Battles into one platform

TypeScript

341

Sideproject

Acasting.se

Modern casting platform

Work

About me

I am a full-stack developer from Sweden with experience in web applications and apps.

Currently I work as a software engineer at @Midjourney, and also a scout for @a16z

First line of code

September 2019

First software engineering job

May 2021

Total prod crashes

1 oops :(

Rank #1000 on CSS Battles

I really like CSS (I don't really get the hate), and one of my favorite sites is CSS Battles where you can compete with CSS. I used to play it a lot and at one point I got to rank 800, but now im sitting at around 1000. There is about 350k total users on the platform.

Matheus Mendes

53700.24 points

(84 Targets)

#1146

Rank #36 in the world

Rank #74 in the world

Rank #36 in the world

Rank #38 in the world

Rank #52 in the world

Rank #62 in the world

Rank #86 in the world

Rank #74 in the world

445 total github contributions in the last year

Midjourney

Software engineer, February 2025 - Now

Adding ability to have multiple layers and rotate layers in the editor on the website
- This required a full refactor of the editor to be able to adapt to the new features
- Redesigned the entire editor to work better with the new tools
Owned the social profiles feature. A tweet about it
- A full new profile page with profile settings and customizability
- Adding the ability to follow other users
- Adding a new interaction called "Spotlighting" that lets users highlight the favorite creations
Added a popup that showed when users ran out out of credits that let them buy new onces or upgrade plane very easily. This popup alone payed for my salary within a couple of weeks

Dema.ai

Software engineer, April 2023 - February 2025

Full-stack ownership of the web-app (core product).
- Owned internal state management with Jotai
- Led and developed a Product Segmentation feature on my own that single-handedly secured multiple clients. This featured handles and labels tens-of-thousands of products per day. See it here
- Developed our Marketing Mix Model feature on the application side. See it here
- Migrated legacy SASS components to custom Chakra UI (moral of the story, chakra is a mistake, just use tailwind)
- Worked on dashboards
- Worked on teams and role-based access control
Owned and wrote almost all of the changelogs, See it here
Built our Shopify integration handling all order and inventory data for our Shopify customers. Later, I created a monorepo for all our other e-commerce integrations, saving multiple hours of dev-time for our engineers. Used Turborepo and deployed it to K8s
Bought a Polaroid camera on my very first day, which has taken well over 300 pictures and has been a core part of the internal employee branding. I also took it one step further on my 1-year anniversary and created a custom page with all Polaroids. See it here

Live site

Dema is an analytis platform for e-commerce that help companies understand there profitably. Its a very cool platform and down below is a small replica to showcase sort of how it looks but also some things you can do. Of course there is A LOT more to the platform than what is down below:)

Dashboard

Reports

Optimizations

Settings

Starting view

Show compare

Channel

Channel group

Visits

Sales

Instagram

Lovable

Part-time consultant, November 2024

Built their landing page over a couple days while i was solo traveling in Thailand. This was part of their rebrand for their third launch, which happened to make them the fastest growing company in Europe ever.

Lovable

@lovable_dev

Nov 21, 2024

Building products takes too long. We started Lovable to fix this.

Today, we`'re officially launching the world`'s first AI Full Stack Engineer

Lovable reliably replicates the capabilities of a full stack engineer and handles everything from design to database operations by integrating with Supabase.

So what`'s new exactly? 🧵

142

642

759

CSS only Rubiks cube

October 2022

The project below was made with a total of ZERO lines of Javascript, its all just CSS. Every animation, hover effect and button click is just a combination of some clever CSS code.

I made this because a friend told me it was not possible to do, so out of spite, I had to prove him wrong. Thats also why if you look very closely in the bakgrund of the real website there is a lot "L"s in the bakgrund

Repository

Live site

Vercel UI

Creator and sole maintainer, 2024

Design library inspired by Vercels design system. It's the same concept as ShadcnUI but does tackle some issue I felt ShadcnUI skips over, like handling multi-part components with multiple different sizes for example.

Repository Live site

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npm init next-app

Blue

Matheus

Is this red?

Vaaarning

npm init next-app

npm init next-app

Blue

Matheus

Is this red?

Vaaarning

npm init next-app

npm init next-app

Blue

Matheus

Is this red?

Vaaarning

npm init next-app

Professional Overwatch Player

2017 - 2020

I was consistently in the top #500 rankings for europe on playstation with multiple different accounts, peking at top #30 at points.
Competed for the scandinavian team in the world cups for Playstation
For certain heroes I was in the top #100 for and peaked #7 for Winston at a certain point.
I was 13-16 years old btw

Acasting.se

First software engineer, part-time consultant, November 2023 - March 2024

Built out the entire app, end to end, together with another engineer, and launched the first version in a single month
Scaled from 0 to 20k users
Was involved in all technical decisions
Handled billions of row reads, and millions of row writes
Developed a custom in-house chat to reduce our monthly costs by over $500/month
Worked on our recommendation engine
Implemented mobile design and responsiveness
Introduced our location feature, helping 100s of casters find amongst 1000+ locations (very similar to Airbnb)

Live site

LucioCode

April - Mars 2021

TLDR; It's Leetcode and CSS battles combined into one that I made in early 2021 for fun. This project also landed me my first job as a software engineer, so it holds a special place in my heart.

Repository

Live site

Simple addition

Easy

Given two integers, a and b, return the sum of a + b

Sample Input

a = 5 
b = 7

Sample Output

Explanation

The sum of of 5 + 7 is 12