Full-Stack Developer Available for work
Based in Brazil

Matheus Malagris

Full-stack developer specializing in serverless architectures, real-time systems, and complex e-commerce integrations. Building production software at Arctic Leaf Inc.

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About

I'm a full-stack developer who started in Electrical Engineering and ended up deep in software — drawn by the same thing: building systems that work precisely and reliably.

At Arctic Leaf, I work across the full stack on client products — from SaaS platforms and e-commerce storefronts to serverless data pipelines and ERP integrations. I like the parts of the job most people avoid: distributed state, third-party API complexity, schema design that has to survive real-world load.

What I love building
Serverless & edge systems
Cloudflare Workers, AWS Lambda — fast, cheap, globally distributed.
Developer-facing APIs
Clean contracts, good DX, OpenAPI docs that actually stay current.
Full-product side projects
From database schema to mobile UI — owning the entire stack solo.
Integrations nobody wants to write
ERP sync, payment webhooks, legacy data feeds. Someone has to.
Background

B.Eng. Electrical Engineering — CEFET-RJ, Brazil. The engineering mindset stuck: I approach software the same way — understand the system, find the constraint, fix it properly.

Experience

Arctic Leaf Inc.
Full-Stack Developer
2022 — Present
Remote
Client Projects
Freelance
Full-Stack Developer
2021 — May 2024
Remote
Client Projects
Daydream Software
Software Developer
Dec 2020 — Dec 2021
Remote (Canada)
Client Projects

Projects

Personal Work
  • Creative
  • Mobile

SynthChord

Music Synthesizer App

Chord-pad synthesizer built on the Nashville Number System — tap diatonic pads or twist a joystick to morph chord quality (maj7, sus4, dim, aug), with Roman numerals and absolute names side by side. Multi-backend audio (dart_melty_soundfont + flutter_pcm_sound PCM loop on mobile/macOS, FluidSynth fallback on desktop/web), three instrument engines (SF2 soundfont, pure-Dart subtractive synth, chromatic WAV sampler), a reorderable effects chain (Freeverb/delay/filter), looper, and arpeggiator. EN/ES/FR/pt-BR UI with a RevenueCat IAP freemium gate; targets Windows, Android, iOS, Web.

FlutterDartRiverpodFluidSynthSoundFontRevenueCat
  • OSS
  • CLI
  • Live

protoglot

Multiprotocol API Client

Local-first, git-friendly API client spanning REST/GraphQL/SOAP/WebSocket/gRPC in a single TOML collection format — a Postman/Bruno alternative published to npm + crates.io. Dynamic gRPC via .proto reflection (no protoc), a CLI-first (pglot) test runner with JUnit/TAP output and CI-correct exit codes, data-driven testing (CSV/JSON) with JSON Schema + snapshot assertions, and JS pre/post-request hooks via boa_engine. A native egui desktop app shares the same engine; Cargo workspace with dual npm + crates.io distribution and SLSA build provenance.

Rusteguitonic (gRPC)boa_enginecrates.io
  • OSS
  • CLI

claude-skills

Claude Code Plugin Marketplace

Curated marketplace of 13 Claude Code skills, each a standalone plugin installable in one line via /plugin marketplace add mqmalagris/claude-skills. Five compose into a single feature-delivery pipeline (grill-me → to-prd → compass → heist → maestro) that takes a feature from vague idea to merged code, each stage consuming the prior artifact and routing back if context is thin. The rest cover language idioms (code-craft: 7 languages, 12 frameworks), deterministic LLM-first SEO audits, OWASP WSTG security testing, and career/content tooling — all built on a progressive-disclosure layout (SKILL.md router loading workflows/topics/reference on demand).

Claude CodeMarkdownJSON manifestsMIT

yield-curves

Rust Yield Curve Library

Pure-Rust library for fixed-income yield curve interpolation, parametric fitting, and bond pricing, published to crates.io with zero third-party numerical crates. Five interpolation methods (piecewise linear, C² cubic spline via Thomas solver, Fritsch-Carlson PCHIP, Nelson-Siegel, Svensson) plus an in-tree Nelder-Mead optimizer, a compounding/forward-rates module (continuous, periodic incl. Brazil-252, simple), bond analytics (Macaulay/modified duration, convexity, par yield off any interpolator), and a zero-dependency date toolkit (ISDA 2006 day counts, BUS/252 ANBIMA calendar, coupon-schedule generation). unsafe_code = "forbid" crate-wide, with SLSA Level 3 build provenance attested per tagged release.

RustPCHIPNelder-MeadSvenssoncrates.io
  • Web
  • Live

CalculeOnline

Brazilian Calculator Platform

PT-BR calculator platform with 140+ static pages across Brazilian tax/payroll, real estate, math, and finance — including a symbolic calculus parser (derivatives/integrals/limits) and 2D/3D function plotters. Astro SSG with Svelte 5 islands; a build-time hook pulls live Selic/CDI/IPCA rates from my own Indicadores-BR API, with a cached snapshot as fallback.

AstroSvelte 5Tailwind v4Chart.jsBun
  • Infra
  • Web
  • Live

Ephemask

Disposable Email Service

Serverless temp email service with dual frontends in a Turborepo monorepo. Go Lambda functions, Terraform-managed AWS infra, freemium model (10-min free / 60-min pro).

GoAWS LambdaTerraformAstroSvelte 5React Native
  • Web

Baby Shower

Baby Shower Event Platform

Public-first event site — no accounts, RLS enforces all access. RSVP with guest counts, gift registry (33 items, 5 categories, DB-level RLS prevents double-reservations), moderated message board, and admin dashboard behind a server-side password gate (Astro SSR).

AstroSvelte 4SupabaseTailwindVercel

Skills

Tech Stack
Frontend
Next.jsReactRemixSvelteAstroVueAngularTypeScriptTailwind CSSReact NativeIonicFlutteregui (Rust desktop)
Backend
Node.jsHonoExpressLoopBackStrapiRust (Axum)GoBunGraphQLgRPC / tonicStalwart
Databases
PostgreSQLMongoDBMySQL / MariaDBDynamoDBSQLite (D1)Supabase
Cloud & Serverless
AWS LambdaSAMCloudflare WorkersD1 / R2 / KVCloudflare PagesSQSSNSSESS3EventBridgeFly.ioHetzner
E-commerce
BigCommerce StencilMiva MVTShopify APISharetribeReChargeStripe
Integrations
DocuSignGoogle APIsHubSpotKlaviyoTwilioSendGridCloudinaryQuickBooksMLS / RETSXorosoft ERPUpstash Redis
Auth & Security
Supabase AuthJWTOAuth2RLS policiesMIVA token auth
DevOps & Tooling
TerraformDockerWranglerCapacitor / CordovaWebpack 5TurborepoStorybookPlaywrightVitestJestinsta / proptestSLSA provenance
AI / ML
LangchainAnthropic Claude APIClaude Code plugins/skills
Mobile
React NativeExpo (SDK 54)FlutterIonic 5CapacitorCordovaexpo-secure-storeexpo-notificationsexpo-printreact-native-svgreact-native-mmkv
Available for work

Let's build
something.

Matheus Malagris
Full-Stack Developer