Full-Stack Developer — Fintech Platform

Post Oak Group; Argentina; Remote; ARS 2,000,000 - 4,000,000; Full time

Job summary

Post Oak Group is seeking an experienced full-stack developer to lead the project from concept through deployment for a fintech platform. The role emphasizes using AI-assisted tools like OpenAI Codex to accelerate progress while maintaining code quality, security, and reliability.

You will design intuitive UIs, build backend systems and APIs, and integrate external services across web and mobile apps (iOS and Android). Strong ownership and US Central Time overlap are expected.

Qualifications

• Strong experience in full-stack development across frontend and backend.
• Proficiency with React, Next.js, Node.js, and TypeScript.
• Experience with React Native or similar cross-platform mobile framework.
• Familiarity with AI-assisted development tools such as Codex, Claude Code, or Cursor.

Responsibilities

• Lead end-to-end development of web and mobile apps (iOS/Android).
• Design responsive, intuitive user interfaces.
• Build and maintain backend systems, databases, auth and APIs.
• Integrate third‑party APIs and external services.
• Leverage AI coding tools to speed up development and improve quality.
• Ensure security, testing, monitoring and deployment best practices.
• Own priorities, timelines and deliverables with leadership.

Skills

Full-stack development

Frontend: React/Next.js/TypeScript

Backend: Node.js & APIs

React Native / cross-platform mobile

AI-assisted development tooling

Education

Bachelor’s degree in CS or related field

Tools

OpenAI Codex

Claude Code

Cursor

Job description

Post Oak Group is developing a financial technology platform and is seeking an experienced, highly motivated full-stack developer capable of independently leading the development of the project from concept through deployment.

The ideal candidate is proficient in modern AI-assisted development tools, including OpenAI Codex, and can leverage these technologies to accelerate development while maintaining high standards of code quality, security, and reliability.

Key Responsibilities

• Lead the end-to-end development of our web and mobile applications (iOS and Android).
• Design and develop intuitive, responsive user interfaces.
• Build and maintain backend systems, databases, authentication, and API integrations.
• Integrate third-party APIs and external services.
• Develop mobile applications compatible with iOS and Android.
• Leverage AI coding tools, including OpenAI Codex, to accelerate development and improve efficiency.
• Implement appropriate application security, testing, monitoring, and deployment practices.
• Independently manage development priorities, timelines, and deliverables while collaborating with Post Oak Group's leadership team.

Qualifications

• Strong experience in full-stack software development, including frontend and backend technologies.
• Proficiency in React, Next.js, Node.js, TypeScript, or comparable frameworks.
• Experience with React Native or similar cross-platform mobile development frameworks.
• Demonstrated experience integrating third-party APIs and developing production applications.
• Familiarity with AI-assisted development tools such as OpenAI Codex, Claude Code, or Cursor.
• Experience with databases, cloud infrastructure, authentication, and application security.
• Previous experience developing fintech or financial services applications is strongly preferred.
• Strong English communication skills, both written and verbal.
• Ability to work independently, take ownership of projects, and collaborate during overlapping U.S. Central Time business hours.

Why Join Post Oak Group?

This is an opportunity to become a founding developer of a new financial technology platform, take ownership of significant technical decisions, and work directly with company leadership to build a scalable fintech product from the ground up.

We are looking for someone who combines strong engineering capabilities with an entrepreneurial mindset, works efficiently with modern AI development tools, and is excited to take ownership of an ambitious fintech project.