Senior Full Stack Engineer (Go + HTMX)

R3 Technology Inc; São Paulo; On-site; BRL 180,000 - 320,000; Full time

Job summary

R3 Technology Inc. in São Paulo, Brazil is seeking a Senior Full Stack Engineer (Go + HTMX) to design, build, test, and maintain production applications using Golang, HTMX, GraphQL, MongoDB, and cloud technologies.

You will work across the SDLC with designers, product owners, architects, and engineers while applying modern cloud, DevOps, and AI-assisted practices to accelerate delivery and improve software quality.

Qualifications

• 6+ years of software development experience with Golang.
• Experience designing REST and GraphQL APIs.
• Proficiency with MongoDB and schema design.
• Experience building server-driven UIs with HTMX; familiarity with Alpine.js and Tailwind CSS.
• Experience with Azure, AWS, or GCP; Azure preferred.
• Experience with CI/CD pipelines, Docker, automated testing, and code reviews.
• Knowledge of AI-Assisted Development Lifecycle (AIDLC).
• Understanding of LLMs, prompt engineering, RAG and AI governance.
• Ability to work in Agile, cross-functional teams.

Responsibilities

• Design and build scalable backend services and APIs using Golang (REST & GraphQL).
• Implement data models and queries in MongoDB with performance focus.
• Collaborate with designers to deliver server-driven UIs using HTMX, Tailwind CSS, and Alpine.js.
• Apply testing, reviews, debugging, CI/CD, and best practices across the lifecycle.
• Deploy and support cloud-based applications; assist in cloud environment operations.
• Apply AI-assisted development practices to coding, testing, and documentation.

Skills

Golang

HTMX

REST APIs

GraphQL

MongoDB

Tailwind CSS

Alpine.js

Cloud Platforms (Azure/AWS/GCP)

CI/CD

Docker

AI-assisted development

LLMs & RAG

Tools

Docker

HTMX templates

Tailwind CSS

Alpine.js

GraphQL tooling

Job description

Job Title- Senior Full Stack Engineer (Go + HTMX)

About the Role:

As a Senior Golang Developer, you will design, build, test, and maintain production applications using Golang, HTMX, GraphQL, MongoDB, and cloud technologies. You will combine strong backend engineering expertise with server-driven UI development to deliver scalable, performant, and maintainable solutions.

You will work across the software development lifecycle, collaborating with designers, product owners, architects, and engineering peers while applying modern cloud, DevOps, and AI-assisted engineering practices to accelerate delivery and improve software quality.

Key Responsibilities:

• Design and build scalable backend services and APIs using Golang, including REST and GraphQL APIs, queries, mutations, and resolvers.
• Implement efficient data models, schemas, and queries using MongoDB, with attention to performance, scalability, and maintainability.
• Collaborate with designers and engineering teams to deliver responsive and accessible interfaces using Tailwind CSS and Alpine.js.
• Apply unit and integration testing, code reviews, debugging, CI/CD, and engineering best practices throughout the development lifecycle.
• Deploy and support applications in cloud environments, troubleshooting issues across development and production.
• Apply AI-assisted development practices across coding, testing, code review, documentation, troubleshooting, and engineering productivity.

Qualifications:

• 6+ years of software development experience, with strong hands-on expertise in Golang.
• Hands-on experience designing and developing REST and GraphQL APIs, including queries, resolvers, and schema design.
• Proficiency with MongoDB, including schema design, querying, and performance optimization.
• Experience building server-driven UIs with HTMX, with familiarity with Templ, Alpine.js, and Tailwind CSS.
• Must have hands-on experience with cloud providers such as Azure, AWS, or GCP, with Microsoft Azure strongly preferred, including deploying and supporting cloud-based applications.
• Experience with CI/CD pipelines, Docker, automated testing, code reviews, debugging, and modern software engineering practices.
• Knowledge of AI-Assisted Development Lifecycle (AIDLC) practices, including the use of AI-powered coding assistants, automated testing, code review, documentation generation, and productivity tools.
• Understanding of Large Language Models (LLMs), prompt engineering, Retrieval-Augmented Generation (RAG), AI governance, and responsible AI principles.
• Experience integrating AI capabilities into enterprise applications through APIs and cloud-native AI services.
• Ability to evaluate and adopt emerging AI technologies to accelerate software delivery and improve quality.
• Strong problem-solving, communication, and collaboration skills, with the ability to work effectively within Agile, cross-functional product teams.

Set Yourself Apart With (Nice to Have)

• Hands-on experience with AI-assisted software development tools and workflows, such as GitHub Copilot, Claude, ChatGPT, or comparable AI-enabled engineering tools.
• Deeper experience applying the AI Development Lifecycle (AIDLC), including responsible AI, prompt engineering, model integration, testing, monitoring, and governance.
• Experience building or integrating AI-powered applications using LLMs, Retrieval-Augmented Generation (RAG), and agentic AI patterns.
• Experience with distributed systems and event-driven architectures.
• Hands-on experience optimizing Go applications for latency, throughput, scalability, and resilience.
• Familiarity with modern DevOps and observability practices in production cloud environment