Senior Software Engineer - AI First, Full Stack - Custom AI Solutions LLC

Senior Software Engineer — AI Platform Custom AI Solutions | Remote (Brazil) | Contract Engagement

About the Role We are looking for a Senior Software Engineer to engage directly with our CTO and engineering leadership as a dedicated platform engineer on VoxaCor™ and BridgeNode™. This is not a staff augmentation role — you will have real ownership across architecture decisions, feature development, and platform reliability.

VoxaCor™ is our AI voice and SMS platform built for high-volume, real-time communication. BridgeNode™ is the open-source AI conversation framework that powers it — every product CAIS builds runs on it. You will own significant surface area across both — from AI agent orchestration and real-time voice pipelines to frontend interfaces and infrastructure.

AI-first development is core to how we build — if you haven't shipped production AI systems, this role isn't for you.

This is a contract engagement. Applicants must have a registered legal entity in Brazil to contract through. This is a firm requirement and is not negotiable.

Key Responsibilities

Build and maintain real-time AI voice pipeline components: STT, TTS, LLM orchestration, and telephony integration

Develop multi-tenant SaaS platform features across web, voice, and SMS channels

Implement AI agent workflows using Mastra orchestration and Anthropic/Gemini LLM integrations

Design and build backend services, APIs, and data models supporting high-volume production workloads

Develop frontend interfaces and progressive web app (PWA) features in React

Build platform tooling, admin interfaces, and partner-facing configuration systems

Contribute to BridgeNode™ open-source framework and VoxaCor™ proprietary feature layers

Tech Stack

Backend: Node.js, TypeScript, PostgreSQL, Docker

Frontend: React 19, TypeScript, Tailwind CSS, shadcn/ui, PWA

Voice & Telephony: Telnyx, Deepgram (STT/TTS), WebRTC, SIP

AI / LLM: Anthropic Claude, Google Gemini, Mastra orchestration

Infrastructure: Azure, GitHub Actions CI/CD, multi-tenant architecture

Compensation

Structure: Paid twice monthly in USD for work performed

On-Target Earnings: $44K–$66K USD - depending on experience

Qualifications

5+ years of full-stack engineering experience with TypeScript/Node.js and React

Production experience building and shipping AI-powered applications — not just prototypes

Hands-on experience with LLM APIs (Anthropic, OpenAI, Gemini, or equivalent) and agent orchestration

Real-time systems experience: WebSockets, streaming APIs, or telephony/voice pipelines

Strong database and API design fundamentals with PostgreSQL

Comfortable working in a multi-tenant SaaS architecture

Professional English proficiency — written and verbal communication must be clear, accurate, and effectiv