What I work on

I build software for companies that operate in Mexico and the US: collecting payments through Stripe, Mercado Pago, SPEI and OXXO, issuing CFDI 4.0 from those payments, reconciling everything against what reached the bank, and adding AI where it takes real work off a team. I write the backend in Go and Python, the web in React, and mobile apps in React Native.

I work in Spanish and English, on US Central time most of the year.

Where I've worked

Nixbly · Founder & full-stack AI engineer (now). A platform where developers meet ideas and ship them together, built on React, Go and AI. nixbly.com
Truxgo · Platform & security engineer. Servers, security hardening and platform work for a Puebla hosting and social-platform company with a 30K-member network.
Hazil Studios (New York) · Shopify e-commerce engineer. Custom themes, storefront apps and performance work across 100+ stores.
Mercanto · Full-stack & mobile engineer. A B2B wholesale marketplace connecting Mexican brands with retailers, on web, iOS and Android.
FinHOA · Fintech SaaS engineer. Dues collection, accounting and resident portals for homeowner associations.

Teaching and writing

I publish 60-second build breakdowns on YouTube, Instagram and TikTok, with more than a million views across them, and I wrote the eBook React in 60 Seconds. On this site I write guides on payments, CFDI and AI engineering for Mexico.

How I use AI in my writing

I use AI tools, mainly Claude, to research topics and draft posts, the same way I use them to write code. I choose the topics, check facts against primary sources (SAT, Banxico, provider documentation), and edit before anything is published. Posts about regulations say when they were written, because rules change. If you find a mistake, tell me and I'll fix it.

Nothing on this site should be read as tax or legal advice. For fiscal rules, check with your contador.

How I handle your data and keys

Payments and invoicing work touches e.firma, digital seal certificates and payment API keys. Here's exactly how I handle them. For this website itself, see the privacy notice.

Contact

The fastest way to reach me is email: hola@cesarayala.dev. Tell me what you're building and where it's stuck; I reply to every message. You can also see the services I offer.