FULL-STACKDEVELOPER

Hi, I'm Leonardo — I build web platforms, mobile apps, and the backends behind them. I work in React and Next.js on the web, Flutter and Dart on mobile, and Node.js or Kotlin with Spring Boot on the server — shipping maintainable software with clean architecture, secure APIs, and intuitive user experiences.

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ReactNext.jsTypeScriptNode.jsExpress.jsNestJSMongoDBPostgreSQLMySQLFlutterDartKotlinSpring BootGraphQLFirebaseJWTREST APIStorybookRAGMCPHITLReactNext.jsTypeScriptNode.jsExpress.jsNestJSMongoDBPostgreSQLMySQLFlutterDartKotlinSpring BootGraphQLFirebaseJWTREST APIStorybookRAGMCPHITL

The developer behind the work.

Full-Stack Developer with six years of experience building web applications, mobile apps, internal dashboards, and backend APIs.

On the web my stack is React, Next.js, Node.js, Express.js, NestJS and TypeScript, over MongoDB, PostgreSQL or MySQL. On mobile it's Flutter and Dart, and on the server I also work in Kotlin with Spring Boot and GraphQL. I enjoy turning complex business workflows into clean, usable, and maintainable software.

On the frontend I focus on reusable components, clear user flows, responsive interfaces, and dashboard experiences. On the backend I work with REST APIs, authentication, authorization, DTO validation, middleware, database operations, and production-ready service structure.

I also build with LLMs — retrieval-augmented generation, the Model Context Protocol, and human-in-the-loop flows where a person reviews and approves what the model produces before it takes effect.

I care about clean architecture, maintainability, performance, security, and business usability — and I'm comfortable owning work end-to-end across the stack with remote teams.

Things I've built & shipped.

QR Pet ID Platform · Live since 2024

Fanstik Tags

A physical pet tag wired to a live web platform. Owners publish a profile behind a QR code; whoever finds the pet scans it, sees the profile, and the owner gets an email with where and on what device it happened. Sold on Amazon and in use today.

644 registered owners and 1,108 pets on the live platform
Scan-to-alert flow: browser geolocation, reverse geocoding to a street address, device fingerprinting, and an email to the owner — all optional per pet
Degrades on purpose: if the finder denies location access the alert still sends, marked Unknown, rather than failing silently
Pet profiles carry a full medical record — vaccines with dose dates, conditions, vet contact — alongside missing, service and ESA flags
Role-based admin over TanStack Table: owners, pets and tag registries, paginated through MongoDB aggregation
Session auth built on jose and bcrypt, with email verification and password reset
24 components and 11 Zod schemas shared between forms and server actions

Next.jsTypeScriptMongoDBMongooseZodSendGridTailwind CSSRadix UI

View project

Offline-First Point of Sale · 2026

Smart Inventory POS

A point-of-sale and inventory system for small shops. Barcode scanning through the device camera, held carts, cash-drawer close-outs and supplier purchases — built to keep selling when the connection drops.

73 test files with Vitest, covering the sales, cash-close and permission paths
51 Convex functions over a 12-table schema — products, sales, held carts, closes, purchases, employees
Offline reads from an IndexedDB mirror via Dexie; writes stay online-only, so there is no sync conflict to resolve
Additive Dexie migrations across three schema versions, mirroring the Convex indexes
In-browser barcode scanning with zxing-wasm — no native app, no hardware scanner
Auth without a third-party package: email plus a 6-digit PIN, with the owner assigning them per employee
15 screens and 14 shared components, ported verbatim from a high-fidelity prototype

ReactTypeScriptConvexDexieViteVitestReact RouterPWA

View project

Ride-Hailing Platform · 2026

Bryngup Driver

A Flutter driver app — ride offers, live trip phases, earnings and payouts — inside a seven-app monorepo built by a team of seven. I joined in July 2026 and took ownership of the authentication and security layer that every app on the platform shares.

Sole author of the platform's second-factor stack: authenticator TOTP, SMS served from our own backend, e-mail codes, and one-time backup codes
Backup codes stored hashed and encrypted at the same time — the hash is what makes 'shown once' literally true, because a dump of the store returns nothing usable
reCAPTCHA Enterprise with server-side verdicts across sign-in and sign-up, plus a bot trap on the registration form
2,663 lines across eleven auth and security modules in the shared package, consumed by all seven apps
Content-Security-Policy headers added to the six web surfaces the platform ships
Retired Maestro in favour of a Flutter integration_test suite — fifteen end-to-end files covering the agent, driver and NTD apps
19 of the 56 commits on the driver app, a 272-file codebase with 44 blocs and 61 screens

FlutterDartBLoCFirebaseFirestoreGraphQLStripeGoogle Maps

View project

Operations Console · 2026

Bryngup Admin

The web console the platform's operators work in — geofence pricing and driver queues, onboarding review, document verification and entity search over live data. Same seven-app Flutter monorepo as the driver app; here I built two modules and hardened the Firestore rules sitting behind them.

Geo-Fence and Queue module: 20 files and 9,861 lines covering surge pricing per zone, FIFO driver queues, a KPI dashboard and the map editor
Shipped it as a front-end design with no backend yet — every value the screens read lives in one file, so swapping it for real repositories changes no screen. The seam was drawn on day one rather than discovered later
130 test cases across ten files for that module alone, 2,151 lines of them
Built the onboarding review queue end to end — bloc, model, table, badges and the approve/reject dialog — 1,792 lines, also shipped with tests
Closed collection enumeration in the Firestore rules: a read grant covers both get and list, so any signed-in client could list every user and vehicle document
Checked the assumption behind that rule instead of trusting its comment — it claimed agents and admins list users, and a sweep of the monorepo found no such query at all; every access goes through a document id
An 811-line rules test harness against the Firestore emulator: 32 cases, one of which verifies the harness itself is sound
A failed query no longer renders as zero results — operators were reading 'nothing to review' when the query had actually broken

FlutterDartBLoCFirestoreFirebase AuthPlutoGridGoogle MapsTurf

Full-Stack Event Platform · 2022–2023

Your Tickets

An event platform for organisers: publish an event through a five-step flow, place the venue on a map, upload media, and configure ticket tiers with pricing and sales windows. Built alongside a full-time role, with an integration suite across every layer.

25 REST endpoints over a layered backend — router, middleware, controller, data — each one covered by tests
78 reusable components, treated as a design system rather than one-off screens
43 test files across three layers — API, pages, and components — with Jest, MSW, and Testing Library
Five-step event creation flow with per-step validation and resumable progress
6-table MySQL schema in hand-written SQL and versioned migrations, no ORM
Versioned API surface (/v1) with centralised error handling and auth middleware
Media uploads to AWS S3 and address autocomplete through Google Maps

Next.jsReactTypeScriptRedux ToolkitMySQLJestMSWTesting LibraryAWS S3

// Additional selected full-stack work available on request.

Skills, by layer.

Frontend

ReactNext.jsTypeScriptJavaScriptTailwind CSSResponsive DesignComponent ArchitectureDashboard Interfaces

Mobile

FlutterDartBLoCFirebaseOffline-FirstPush NotificationsGoogle MapsIn-App Payments

Backend

Node.jsKotlinSpring BootGraphQLExpress.jsNestJSREST APIsDTO ValidationMiddlewareGuardsError HandlingLoggingHealth Checks

Database

MongoDBFirestoreRealtime DatabasePostgreSQLMySQLMongooseData ModelingCRUD OperationsQuery Optimization

Auth & Security

JWTTwo-Factor AuthTOTPreCAPTCHA EnterpriseContent-Security-PolicyFirestore RulesRole-Based Access ControlProtected RoutesAPI AuthorizationSecure Backend Flows

AI Engineering

RAG (Retrieval-Augmented Generation)MCP (Model Context Protocol)HITL (Human-in-the-Loop)

Practices

GitGitHubCI/CDMonoreposEnd-to-End TestingStorybookCode ReviewsTechnical DocumentationRemote Collaboration

Clean ArchitectureMaintainableSecure APIsProduction-ReadyRemote-FriendlyClean ArchitectureMaintainableSecure APIsProduction-ReadyRemote-Friendly

How I build.

I approach full-stack development with a practical mindset: understand the business flow, design a clean user experience, define reliable API contracts, and build a system that can grow without becoming difficult to maintain.

On the frontend, I focus on reusable components, clear navigation, responsive layouts, and dashboard usability. On the backend, I care about validation, authentication, authorization, error handling, logging, and clean service structure — code that other developers can read, extend, and trust.

Maintainability first

Clear frontend/backend boundaries, reusable components, predictable API contracts.

Business workflow aware

Technical decisions follow real flows — not the other way around.

Secure by default

Authentication, permissions, error paths, and edge cases handled deliberately.

Clear communication

Documented decisions, clean PRs, code the next developer can extend.

Ready for remote teams.

I'm comfortable working with remote teams where communication, ownership, and clarity matter. I work independently, document decisions, communicate blockers early, and collaborate with developers, designers, and stakeholders across different workflows.

Asynchronous communication
Strong written communication
Documents technical decisions
Works independently with ownership
Adapts to existing codebases
Responsible with deadlines

LET'S BUILD
SOMETHING reliable.

If you're looking for a Full-Stack Developer who can work across React, Next.js, Flutter, Node.js, NestJS and Kotlin with Spring Boot — I'd be happy to connect.

LinkedIn/in/leonardo-socorro GitHub@lion-ctrl Emailleonardo.novaro.ln