David Del Toro

Mobile • Senior • Rancho Cucamonga, USA • UTC-08:00 • Work permits: United States

Backend Developer

Node JS

Python

SQL

JavaScript

Kotlin

TypeScript

Java

Active 2 days ago

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Overview

Technical skills

Timeline

Roles

Overview

Backend Java engineer (senior-level) focused on Spring Boot services and domain-specific systems for game tooling. The strongest proven skill is building backend domain logic and concurrent integrations as shown by ComboServiceImpl (CompletableFutures, dedicated Executor, HttpClient integration) and the DeckOptimizerV2 algorithmic optimizer. Mobile work, adaptive UI, background OS-limited tasks, app store release pipelines and native mobile integrations are not evidenced in public code.

Technical skills

Node JS• Middle

Python• Middle

SQL

JavaScript

Kotlin• Senior

TypeScript• Middle

Java• Senior

Node JS

Express

Bcrypt

Kotlin

Mockito

Java

Spring Boot

Hibernate

Spring Framework

Spring Security

Jackson

AssertJ

Lombok

Databases

PostgreSQL

Frontend

HTMX

React.js

Tailwind CSS

PostCSS

Next.js

Vite

Material UI

Zod

ESLint

autoprefixer

MSW

Mobile

JUnit

Dependency Injection

DevOps

Docker

Git

gRPC

Vercel

AI/ML

Computer Vision

OpenCV

Timeline

Trading Card Builder and Trader

Website

Jan 2025 to Present 1 Year 7 Months

Java

Python

JavaScript

California State University (Fullerton Campus)

Master's Degree • Computer Science

2025–2026 Fullerton, California

Senior Mobile Developer Confidence: Medium Generalist

Platform Native Mastery

Knowing the mobile platform

Not evidenced in public code

Mobile UI/UX & Responsiveness

Smooth mobile experience

Not evidenced in public code

Performance & Battery

Speed and battery use

Not evidenced in public code

Offline & Data Sync

Working offline and syncing

Not evidenced in public code

Device Integration

Using device features

Not evidenced in public code

Release & App Lifecycle

Building and publishing apps

Not evidenced in public code

Industries

Gaming• Middle

Technologies

Java• Senior

Kotlin• Senior

JUnit

Spring Framework

Jackson

Spring Boot

Mockito

Spring Security

Lombok

AssertJ

Dependency Injection

Recommendations

Develop backend services for games or hobby platforms that need domain logic, caching and async integrations, for example combo-finding or deck-simulation services.
Implement server-side components that integrate with external APIs or gRPC services while hardening retry and rate-limit handling as shown in ComboServiceImpl.
Lead algorithmic feature work such as search, simulation or optimization engines (extend DeckOptimizerV2 with benchmarking and vectorized tests).
Expand into cross-functional roles where backend, eventing and integration testing are required, such as microservice design, cache strategies and CI-driven integration tests.

Repositories

The developer's experience in this domain has been verified based on AI analysis of the following repositories:

Java-MTG-Deckbuilder neetcode-submissions neetcode-submissions-6p2a239k

Middle Backend Developer Confidence: Medium API Engineer

Backend engineer focused on API-driven web applications and integrations at a middle level with strong service layering and pragmatic engineering. The strongest proven skill is building and integrating REST/gRPC services with accompanying repositories and caches, as shown by the Spring controllers and GrpcCardScannerClient plus cache/config classes. There is limited public evidence of production-grade infra (metrics/alerting, migration history, or explicit rate limiting) and some third-party vendored libraries are present in the tree rather than being referenced as external dependencies.

API Design

4/10

How well APIs are designed

API design shows deliberate controller/service separation, centralized exception handling and a gRPC client integration, but lacks explicit versioning, idempotency controls and documented API contracts.

Evidence

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/controllers/CardBrowserController.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/advice/GlobalExceptionHandler.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/service/impl/GrpcCardScannerClient.java

Data Layer & Database

4/10

Working with databases

Data layer uses hand-written JDBC repositories, custom RowMappers and integration tests which indicate conscious data-access design, but there is limited visible schema-migration history and few examples of advanced tuning or explicit transaction/isolation reasoning.

Evidence

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/repository/impl/CardRepositoryImpl.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/repository/impl/PersonalLibraryRepositoryImpl.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/mapper/OwnedCardRowMapper.java

Scalability & Performance

4/10

Handling load and speed

There are clear scalability-focused choices such as Caffeine caching, async listeners and use of CompletableFuture/executors and a decoupled gRPC scanner, but no strong evidence of measured load testing, cache invalidation policies with telemetry, or sophisticated rate-limiting/queueing.

Evidence

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/config/CacheConfig.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/cache/PersonalLibraryCache.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/service/impl/ComboServiceImpl.java

System Architecture

4/10

Overall system structure

The system is modular with controllers, services, repositories, async subscribers and a separate scanner runtime (gRPC), showing intentional decomposition and event-driven cache invalidation, though it's not at the level of multi-service production orchestration with explicit service contracts or config/secret management artifacts.

Evidence

scanner-runtime/grpc_server.py

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/service/impl/GrpcCardScannerClient.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/subscribers/LibraryCacheEvictionListener.java

Security & Auth

5/10

Protecting data and access

Security and auth are addressed at multiple layers: Spring Security configuration, custom authentication filter and sanitization aspect for inputs, plus password encoding, which indicates awareness of authn/authz and input hygiene.

Evidence

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/config/SecurityConfig.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/advice/SanitizationAspect.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/security/DemoAuthenticationFilter.java

Reliability & Observability

3/10

Stability and monitoring

There is central exception handling and some async retry/async task patterns, but limited evidence of structured observability (metrics, traces), consistent timeouts/retries with backoff, or deployment/runbook artifacts for reliability.

Evidence

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/advice/GlobalExceptionHandler.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/subscribers/ComboRefreshListener.java

Java-MTG-Deckbuilder/src/main/java/com/example/mtg_deckbuilder/service/impl/GrpcCardScannerClient.java

Verified artifacts

PDang176/mtg-ocr• contrib

Expertise

Java• Middle

Microservices & API Architecture• Middle

Python• Middle

Node.js• Junior

Industries

Gaming• Middle

Technologies

Python• Middle

SQL

PostgreSQL

gRPC

Vercel

Hibernate

Git

Docker

Recommendations

Lead development of REST + gRPC backends that integrate image-processing or external service clients, including implementing strong client-side timeouts and retry/backoff strategies.
Implement platform-focused features such as metrics/tracing (OpenTelemetry), structured logs with correlation ids, and alerting on cache/queue failures.
Improve data layer maturity: add explicit migration history, document schema evolution, and add more hand-tuned queries/index guidance with performance tests.
Extend event-driven flows into clear contracts (versioned events) and add end-to-end integration tests that simulate async subscribers and cache eviction.

Repositories

The developer's experience in this domain has been verified based on AI analysis of the following repositories:

Java-MTG-Deckbuilder neetcode-submissions React-MTG-Builder

Middle Frontend Developer Confidence: Medium Fullstack

Fullstack web developer at a middle level with a clear strength in polished frontend UI and CSS craftsmanship. The strongest proven skill is visual UI design and polished interactions as shown by the hand-authored styles in ToroDDT/Portfolio/src/App.css and ToroDDT/Portfolio/src/resume.css. There is limited public evidence of advanced client-side async state management, accessibility engineering, measured performance optimization or large-scale system architecture.

UI Component Architecture

3/10

How interface parts are built

UI work shows strong visual/CSS craft but lacks clear component architecture, composition patterns or a bespoke design-system authored by the developer.

Evidence

ToroDDT/Portfolio/src/App.css: extensive hand-authored styling and UI sections without accompanying component files in the sample ToroDDT/Portfolio/src/resume.css: custom modal and responsive layout styling indicating visual design effort ToroDDT/Customer-Management-System-Gym/management_app/package.json: presence of @mui/material showing use of a UI library rather than a custom component system

Responsive & Cross-browser

4/10

Works on all screens and browsers

Responsive CSS and modern features are used (clamp, media queries, prefers-reduced-motion) but there is no evidence of RTL support, advanced fluid type or feature-detection strategies.

Evidence

ToroDDT/Portfolio/src/App.css: responsive rules, clamp for font sizes and @media adjustments ToroDDT/Portfolio/src/resume.css: mobile bottom-sheet pattern and media-query driven layout changes ToroDDT/Calculator/styles.css: responsive visual layout and grid usage for calculator UI

Performance Optimization

2/10

Speed of the interface

Minimal evidence of deliberate performance engineering beyond using modern tooling; no profiling, bundle analysis, advanced code-splitting or large-list virtualization present.

Evidence

ToroDDT/Portfolio/package.json: vite listed as the dev/build tool ToroDDT/Portfolio/vite.config.js: basic Vite setup with React plugin

Accessibility & Semantics

3/10

Usable for everyone

Some semantic HTML and reduced-motion support are present, but there is little explicit ARIA, focus-management, keyboard handling or CI a11y tooling shown.

Evidence

ToroDDT/Portfolio/src/App.css: use of semantic elements (nav, section, footer) and visual focus-related CSS ToroDDT/Portfolio/src/resume.css: respects prefers-reduced-motion ToroDDT/Calculator/index.html: semantic structure for the interactive UI

State Management & Data Flow

3/10

Managing data in the app

Server-side flows and basic validation/auth patterns are implemented, but advanced client-side async discipline, cancellation, optimistic updates or state machines are not evidenced.

Evidence

ToroDDT/Customer-Management-System-Gym/management_app/auth.ts: NextAuth provider with zod validation and bcrypt password verification ToroDDT/Customer-Management-System-Gym/management_app/express/server/controllers/leadsController.js: asyncHandler controllers using Mongoose models ToroDDT/Customer-Management-System-Gym/management_app/lib/fetchActiveSubs/fetchActiveSubs.ts: server-side data retrieval with test harness

UX & Visual Polish

5/10

Look and feel quality

High visual polish, thoughtful animations and UI states are present in CSS and styles, improving perceived experience, although many are CSS-only and not tied to advanced UX patterns like undo or progressive loading metrics.

Evidence

ToroDDT/Portfolio/src/App.css: detailed hero, card, chat-demo and animation styles ToroDDT/Portfolio/src/resume.css: polished modal animations and mobile sheet ToroDDT/Calculator/styles.css and ToroDDT/Calculator/script.js: polished visual styles paired with a custom calculator UX implementation

Expertise

React• Middle

Frontend Architecture & Build Tools• Middle

HTML & CSS• Middle

Industries

Lifestyle• Middle

Technologies

JavaScript

TypeScript• Middle

Node JS• Middle

HTMX

Tailwind CSS

Next.js

Express

Bcrypt

React.js

Vite

Material UI

PostCSS

ESLint

Zod

MSW

autoprefixer

Recommendations

Lead implementation of customer-facing dashboards and marketing pages where visual polish and responsive CSS matter.
Develop small-to-medium Next.js fullstack features that combine authentication and server-side data flows, leveraging the existing auth.ts and Express controllers.
Convert core UI patterns into a reusable component library with documented accessibility and focused component boundaries.
Introduce measured performance work such as bundle analysis, code-splitting, and RUM metrics to validate visual optimizations.

Repositories

The developer's experience in this domain has been verified based on AI analysis of the following repositories:

Portfolio Customer-Management-System-Gym Calculator