João Vitor
builds software that scales.

A new NFCom invoice module had to ship inside a large legacy AngularJS application — looking native to it — without piling conditional logic onto a codebase owned by another team, and without a risky rewrite.

As the sole developer, I prototyped three integration strategies — iframes, Module Federation, and Single-SPA — and chose Single-SPA parcels with import maps. The React + TypeScript page exports lifecycles consumed by the host, renders on the same page and host — reusing the existing authentication token — and ships behind a per-client module toggle.

The NFCom frontend deploys independently and the legacy team never had to touch it. The module serves a client issuing millions of fiscal documents per day.

An enterprise client made SSO through their own identity provider a security requirement for closing the deal — and Monitor, one of the company's main applications, only had its own login.

Built solo: Keycloak supporting both OIDC and SAML, a dedicated IdP and isolated environment per client, and a white-label login theme matching Monitor's UI, baked into a custom Keycloak Docker image. Rollout was controlled by a per-client module toggle.

The feature helped close the enterprise deal and was later adopted by more clients — a new client can be configured in under a week. After the Avalara acquisition, I presented the architecture to Avalara's Architecture Review Board to greenlight a new rollout.

Issuing and cancelling NFCom invoices at national scale, with every processing step traceable and retained for legal compliance.

Flow is 15+ single-responsibility Java/Spring microservices coordinated through Kafka events — with retries, dead-letter queues for gap detection, and events retained for at least three months for legal reasons. I designed and implemented the cancellation workflow end-to-end, which meant understanding the entire pipeline first, and built a new service consuming Elasticsearch data.

The platform handles millions of documents per day, scaling horizontally on Kubernetes.

Croct — a personalization and A/B testing platform — needed every product, site, and docs page to share one consistent, tested, accessible UI.

Helped build a 130+ component library under a strict pixel-perfect workflow: components implemented exactly as designed in Figma, every PR reviewed by the design team — one wrong pixel blocked the merge. Product wrote BDD scenarios in natural language that became Cucumber e2e tests; CI blocked PRs under 90% unit coverage. Accessibility was validated with screen readers, keyboard navigation, and role-based queries.

Every Croct surface ships from the same accessible design system — sections I built are live on the public site and docs.