Johnson Mauro

I'm a

About me

13+
Years shipping software
10+
Companies served
3,800+
Hours of tracked coding
40+
Projects with 10+ hours each

Hi There 👋🏽

Software engineer with 13+ years across telecom, healthcare, retail and education, from .NET ERPs and RPA bots to web and mobile apps in React, Angular, TypeScript and Node.js. I modernize legacy systems while they keep shipping and back each change with tests. Since 2026 I also deliver with AI coding agents: I write the specs, delegate implementation and verify every diff with tests and review.

Current focus

Co-leading the React 19 rewrite of a US telephony platform and, as partner in an ERP startup, building its field-sales mobile app.

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Skills

Stack

Primary

  • TypeScript
  • React / React Native
  • Angular
  • Expo
  • Node.js
  • NestJS
  • Go
  • PostgreSQL

Production experience

  • Next.js
  • .NET
  • Vue
  • Svelte
  • Solid
  • Ionic
  • SQL Server
  • MySQL

Tools & AI

  • Vitest
  • Playwright
  • GitHub Actions
  • AWS
  • Azure DevOps
  • Jira
  • Claude Code
  • Codex
  • MCP

Engineering judgment

  • Legacy modernization
  • Offline-first mobile
  • Multi-tenant APIs
  • OAuth & webhook integrations
  • Real-time messaging
  • WCAG 2.2 AA
  • OWASP hardening
  • Team standards & mentoring

How I work now

I direct the agents. I own the result.

The same habits, applied to AI agents: less time typing code, more time deciding what gets built, how agents build it, and whether it is right. Each practice below is backed by work in real repositories.

  1. Agent context design

    40+ Claude Code skills and CLAUDE.md contracts across 7 repositories, turning team conventions into rules agents follow.

  2. Spec-first delegation

    Plans, ADRs and acceptance criteria before code; 200+ agent-paired commits since March 2026.

  3. Verification over trust

    TDD and human review on every agent diff: 1,300+ tests in projects I own, plus a 0→3k suite in a co-led rewrite.

  4. Architecture guardrails

    DDD and feature-sliced boundaries enforced by lint, plus security and accessibility skills agents must apply.

Experience

2022 – today

Modernization, now with AI agents

Rewriting a 12-year-old product while it keeps shipping, owning integrations end to end and building mobile and web for clients. Since 2026, the same work is delivered with AI agents under specs, tests and review.

  1. Software Engineer

    Jan 2022 - Present

    InPhonex

    • Co-led the rewrite of a 227k-line telephony admin app from React 16/CRA to React 19, Vite 8 and TypeScript 6: 788 commits, #2 of 22.
    • Grew test coverage from zero to ~3,000 cases and 71.5% of lines, adding 459 test files with Vitest and Testing Library.
    • Built a CRM-to-telephony integration end to end, with a 14-module API, embedded calling SDK and 985 tests, using NestJS, NATS and Playwright.
    • Standardized AI-assisted delivery across 4 team repositories with 26 Claude Code skills and ~1.2k lines of agent context.
    • Cut dependency install size 37% (720 to 454 MB) by migrating Yarn to pnpm.
    • Shipped 1,135 commits to the 12-year-old AngularJS product while the rewrite progressed.

  2. Partner & Software Engineer

    May 2026 - Present

    ERP startup

    • Built a field-sales mobile app solo in 6 weeks: 92 commits, 13 screens, ~18k lines, using Expo SDK 56, React Native 0.85 and TypeScript.
    • Designed offline-first ordering across 8 DDD modules, queuing orders in on-device SQLite and syncing in the background.
    • Wrote ~347 unit and component tests; 53% of commits were paired with Claude Code, guided by 8 custom project skills.
    • Delivered the ERP returns module in 5 phases (~6k lines), covering the .NET 10 API, a React wizard and returns e-invoicing.

  3. Freelance Software Engineer

    Sep 2025 - Present

    Freelance clients

    • Shipped a bilingual English-school platform from v1.0 to v2.4: 91 commits, 14 merged PRs, push-to-deploy CI, built with Next.js 16.
    • Reached Lighthouse mobile scores of 96 accessibility, 100 best practices and 100 SEO after a WCAG 2.2 AA pass.
    • Closed a 10-finding OWASP-aligned audit, adding HSTS, CSP and COOP headers and patching 16 vulnerable dependencies.
    • Designed a multi-tenant REST API with 19 endpoints, role-based JWT and 11 documented ADRs, tested against real PostgreSQL in Go.

  4. Open-source contributor

    Jul 2026 - Present

    Browser extension for a game trading site

    • Merged 2 PRs into a 38k-line Chrome and Firefox extension, including a scroll bug fix backed by 9 regression tests (Svelte 5, WXT).

2018 – 2022

Products, mobile and automation

Four years across web and mobile products in health and mobility, BI dashboards and RPA bots for telecom operators, and the front end of a conversational-AI product.

  1. Software Engineer

    Oct 2021 - Feb 2022

    Accountfy

    • Delivered front-end features, proofs of concept and tech-debt removal in 5 months, and trained the team (AngularJS, Commerce Cloud).

  2. Software Engineer

    Oct 2020 - Aug 2021

    IT Lean

    • Built the front end of Leanbot, a proprietary conversational-AI product, over 11 months (Angular, PO-UI, Node.js, PostgreSQL, AWS).

  3. Software Engineer (parallel side project)

    Jan 2020 - Jun 2021

    nevtec.eu

    • Delivered on-demand front-end work as a freelancer for 18 months (React, React Native, Node.js, GraphQL).

  4. Software Engineer

    Jun 2020 - Aug 2020

    Foco Aluguel de Carros

    • In 3 months, built Coral, a fleet check-in and check-out system, and ran client and supplier meetings (Angular, Node.js, MySQL, Power BI).

  5. Software Engineer

    Aug 2019 - Jun 2020

    Devexo (OrtoClin)

    • Developed a dental-health product across 2 platforms, web and mobile (Angular, Ionic, React Native, .NET Core, SQL Server).

  6. Associate Software Engineer

    Jun 2018 - Aug 2019

    Avanade

    • Delivered 8 Power BI dashboards for 3 top-tier Brazilian telecom operators, cutting executive report lag from D+5 to D+1.
    • Built 5 RPA bots that eliminated ~30 back-office hours per week across billing and ticket triage.
    • Migrated ~2M rows/day from legacy mainframe tables into a SQL Server warehouse through a scheduled ETL pipeline.

  7. Software Engineer

    Jan 2018 - Jun 2018

    Tella World

    • Built the front end of iBoltt, a ride- and delivery-sharing mobile app, in 6 months (AngularJS, Node.js).

2012 – 2017

Foundations

Five years of full-stack .NET: an in-house ERP and software-factory projects, owning delivery from database to screen.

  1. Software Engineer

    Oct 2012 - Dec 2017

    Qualytech

    • Over 5 years, built ConsegnaERP for small businesses and ran software-factory projects for utility, education and real-estate clients (WebForms, .NET, SQL Server).