Cofounder and CTO, Woovi

São Paulo, Brazil

@sseraphini

SibeliusSeraphini

I build payment infrastructure on Pix at Woovi, teach GraphQL and Relay, and mentor developers and founders. Whatever I learn along the way, I write down so you can skip the hard parts.

Read my writingWork with me

With the receipts

What I'm good at

Payments on Pix

As cofounder and CTO of Woovi, I build the platform Brazilian businesses use to charge, pay and reconcile with Pix, Brazil's instant payment system.

WooviPix, visualizedWhat is expected from a CTO of a startup?

GraphQL and Relay

I have been teaching Relay since Relay Modern came out, through workshops, deep dives and server-side rendering in production.

relay-workshoplearn-relayRelay Modern: What is a Fragment?

Infrastructure you own

Terraform, Proxmox, Talos, Kubernetes and CI that we run ourselves, so the bill and the outages stay ours to fix.

Proxmox, visualizedHow to self-host any open source service?Tekton CI/CD, visualized

Growing developers

I help juniors become seniors and seniors become leads, through mentorship and by answering every question once, in public.

How to become a senior engineer faster?Mentorship answersLearning paths

For developers who want to grow

Learn with me

Roadmaps
Step-by-step routes through React, backend, DevOps, Docker and more. Tick the steps as you go.
Hiring questions
The questions I ask when hiring, with the answers I look for. Practise them like flashcards.
Ask me
Ask anything about software, startups or your career. I answer in public, so everyone learns from it.
Substack, dev.to and Medium, newest first

Writing

All posts on SubstackAll posts on dev.toAll posts on Medium

Study companions where every chapter is a simulation

Visualized

Books and systems I wanted to understand properly, rebuilt as things you can drag, step through and break.

On GitHub as @sibelius

Code

Open source Woovi and I build on

Tools we run

We run most of our infrastructure on our own machines, on open source. These are the services we host ourselves; each one links to where we wrote about it.

The whole stack, 27 tools with sources

245 notes, linked by tag and by hand

Notes

Short, unfinished notes on learning, startups, career and code. I write things down so I only have to figure them out once. Pick a tag, search, or click any dot.

Open the full graphAll tags

Good ones to start with

  • thinkinglearning
    Being wrong

    You can be wrong in many situations Make sure to always revalidate your ideas on new information like Bayesian approach P(A I): your probability of something should changed based…

  • bookslearningmentorship
    Books as answers

    I believe we can learn a lot in books. We can learn knowledge that author took some years to figure it out in a few hours or days. It is like compressing your learning When…

  • careerrisk
    Career Risk

    Most people does not optimize to take career risks. I have a lot of smart friends that are stuck on bad jobs (learning almost nothing, and without change of growth) that can't…

  • startupsbehavior
    Change

    Most people only change when a change happen to them Big companies (winners) only moves when something changes Startups should change/adapt before the change come Links

  • architecturedesign
    Constraint are good

    Most people think about constraint in a bad way I think constraint is good for many reasons Constraints gives you a limited set of options to perform or use. GraphQL is better…

  • riskbooks
    Black Swan

    Black swan is an unexpected event that causes massive consequences. One event that usually happens on the tail of the propability. The last black swan as covid19. Covid19 is a new…

Browse all 245 notes
Same ideas, out loud

Talks and everywhere else

Slides from my talks are on SpeakerDeck, recordings onYouTube, and conversations on a few podcasts. Day to day I think out loud on X as @sseraphini. The longer essays live inFood for thought.

Latest slides

Talks and interviews

All 10 decks, 22 talks and 3 podcast episodes

For when you want the conversation, not only the notes

Work with me

US$ 120a month
Mentorship for developers

One call a month and async chat every day, to land the first job, reach the next level or start leading a team.

US$ 120a month
Consulting for startups

Set up how the team works, cut the scope down to a real MVP and read your cohorts.

On requesttalk to me first
Consulting for fintechs

Payments on Pix, ledgers and reconciliation, and running the infrastructure yourself, from someone building it every day at Woovi.

US$ 10a month
Private community

A Discord of people building products, startups and software, where you bring your work and get it read.

Pay with Pix

Pix, any amount

GitHub Sponsors outside Brazil

Support the writing

Everything here is free and stays free. If something helped you, a Pix keeps more of it coming.

Open original