Cristhofer Cousiño

Full-Stack & Forward Deployed EngineerFull-Stack EngineerSantiago, ChileChileAvailable nowAvailable

Forward deployed engineer for a US fintech: I work inside the finance teams of construction companies, scope what they need with them and ship it to production. Before that I led the platform work on Replicator, a BI and data replication system.

I work mostly in Java, Go and TypeScript, on Spring Boot, Next.js and PostgreSQL. Self-taught, shipping production software since 2023, and certified C2 in English.

46% to 71%of invoice amounts captured automatically, measured on 677 invoices
About 30dashboards moved onto a new platform, along with the company portal
2US construction companies, working directly with their accountants and owners

amarucouss@gmail.comEmail

github.com/amarucoussGitHub LinkedIn amarucouss.comWebsite

Work

Click any screenshot to open the full set. All repositories

Software

2026Open source

Completionist

Go and Next.js monorepo for a social tracking platform. Auth, profiles, lists, posts, challenges and websocket messaging, with media pulled from TMDB, Jikan, RAWG, Google Books, Steam and Last.fm behind one interface.

Go 1.25Next.js 16PostgreSQLWebSocketsAWS S3

Code

2026In progress

Tsukimi Reader

Manga reader for Linux, Windows and Android, with a Go backend and a React interface. Its catalogue lists 387 sources: 187 built in, plus Aidoku's WebAssembly packages and Paperback's JavaScript bundles, loaded only while in use. One library stays in sync between phone and desktop through a shared folder or over the network.

Go 1.27Wails v3React 18TypeScriptSQLiteWebAssemblyAndroid

2026Live

Total Trades Integrated

Brand site for a commercial and industrial contracting firm covering MEP, welding and construction. Built around their service structure and a quote request flow.

Next.js 15React 19TypeScriptTailwind CSS 4

Visit

2026Private

Accounting Automation Portal

Internal portal for a construction company's accounting team. Generates lien waivers, auto-files incoming vendor PDFs, tracks compliance by project and vendor, and holds outgoing emails in a review queue. Microsoft SSO with role-based access and an audit log.

PythonFastAPINext.js 15React 19PostgreSQLAWS

2026Private

Habit Tracker

Go API and Next.js client where progression is computed server-side: XP, levels, streaks and weighted attributes, with protected history edits and CSV exports.

Go 1.25Next.js 16PostgreSQLBunTailwind CSS 4

2026In progress

Adaptive Commerce Platform

Backend-first headless commerce monorepo. A Go core drives both the storefront and the admin dashboard, with payment and delivery providers behind adapters and runtime profiles per brand.

Go 1.25Next.js 15PostgreSQLBunTebex

2025Private

Replicator

BI and data replication platform for construction. Discovers schemas in legacy ERPs (Viewpoint Vista, Spectrum), streams them into a Postgres warehouse, and exposes a visual query builder and drag-and-drop dashboards on top.

Java 21Spring BootNext.js 16PostgreSQLAWS

Game development

2026Private

Hero Arena Gamemode

Round-based hero PvP for a Minecraft event server, plus the tournament backbone it runs on: a Velocity proxy holding team and score authority, a lobby plugin, and an API other minigames plug into.

JavaPaperVelocityRedisWebSocketsGradle

2026Private

Minecraft Chaos Randomizer

Paper plugin that turns Minecraft into a hardcore run: 50 tunable chaos events on weighted schedules, randomized drops, crafting and spawns, and a world reset on death.

JavaPaperMythicMobsBetterHudBetterModelGradle

2025Open source

Paper Setup Plugin

Gradle plugin that sets up a PaperMC server for plugin development: downloads the jar, accepts the EULA, installs the built plugin and runs it. Published on the Gradle Plugin Portal.

KotlinGradleREST APIsBuild Automation

Code

2026Open source

Hytale Setup Plugin

Gradle plugin for automated Hytale server setup: versioned downloads, asset extraction, release channels, and an interactive local run task.

KotlinGradleHytale DownloaderJVM Toolchains

Code

Experience

2026 - Present

Full-Stack / Forward Deployed Engineer · Contract, US fintech

Embedded with two US construction companies' finance and operations teams: I scope work with their accountants and owners and take it to production. Solo until September, then leading two engineers.

Automated accounts payable from email to approval with OCR and coding rules, raising invoice amount capture from 46% to 71% on 677 invoices.
Built a multi-tenant, mobile-first CRM for construction subcontractors and moved a company into it from Pipedrive.
Moved about 30 dashboards and the company portal onto the fintech's platform, including crew timecards with approvals.
Ported the accounts payable logic into the team's Go service (Echo, GORM, PostgreSQL) and its React front end.
Built receipt and company card reconciliation with document AI and Gemini, Microsoft Entra sign-in across the apps, and daily ERP refreshes from Jonas Premier.
Rebuilt a company's public website and built a tool to review, edit and schedule its newsletter with photos from SharePoint.

GoPythonTypeScriptReactNext.jsPostgreSQLGCPAWS

2023 - Present

Software Engineer · Freelance

Custom software for clients in Chile and the United States: backends, internal tools and apps.

Built an accounting automation portal for a US construction firm: a FastAPI backend with over 200 endpoints behind a Next.js front end, Microsoft Entra ID single sign-on, role-based access and an audit log.
Shipped product and marketing front ends in Next.js and React, plus the REST APIs behind them, with explicit contracts and versioned PostgreSQL migrations.
Ran client work end to end in English: scoping, delivery on a date, and handover that stayed maintainable.

JavaKotlinGoPythonNext.jsTypeScriptPostgreSQLFastAPIAWS

2024 - 2025

Lead Software Engineer · Replicator Platform

Led design and development of a BI and data replication platform for legacy ERPs, with a Spring Boot API of over 150 endpoints.

Designed a hybrid multi-tenant model in PostgreSQL: one schema per tenant for ERP data, row level security for shared metadata.
Built a replication engine in Java 21 that discovers legacy ERP schemas, runs full or incremental loads, and streams into Postgres in binary format.
Delivered a Next.js front end with a visual query builder, drag-and-drop dashboards and S-curve financial forecasting.
Deployed AWS infrastructure using Secrets Manager for external credentials and OAuth2/OIDC for identity.

Java 21Spring BootNext.jsPostgreSQLAWS

Curriculum vitae

One page, English or Spanish

PDF or DOCXsingle columnupdated 2026

Read onlineRead

Languages: Spanish, native
English, CEFR C2View EF SET certificate
Based in: Santiago, Chile
Overlaps US Eastern Timeremote, hybrid or on-site
Education: Self-taught
Since 2023, through docs and shipped projects
Core stack: Java, Go, TypeScript
Spring Boot, Next.js, PostgreSQL, Docker, AWS
Also worked with: Kotlin, Python
FastAPI, Redis, Terraform, Azure, Paper API
Open to: Backend, full-stack, product
Full-time, contract or long-term collaboration

Contact

Send the role or the problem you are trying to solve and I will reply with the closest thing I have built.

amarucouss@gmail.com

GitHub: github.com/amarucouss
LinkedIn: Cristhofer Cousiño
English certificate: EF SET, C2 Proficient, 80/100