Senior Full Stack Engineer

Firmable Pty Ltd; Melbourne; Híbrido; AUD 140.000 - 190.000; Jornada completa

Descripción de la vacante

Firmable Pty Ltd in Melbourne is seeking a Senior Full Stack Engineer with a focus on AI to ship end-to-end features across the stack. You will own work from spec to production in collaboration with product, design, and the local Australian engineering team.

The role requires shipping production web features, strong backend fundamentals, and hands-on AI tooling. This is a hybrid opportunity with a focus on delivering scalable, AI-enabled solutions.

Formación

• 5+ years shipping production web and Next.js.
• Strong backend fundamentals: REST API design, relational data modelling in Postgres, auth and multi-tenancy patterns.
• Agentic AI hands-on: shipped features using LLMs (tool calling, RAG, agents).
• AI-native workflow: using Claude Code, Cursor or similar daily.
• Excellent written English and stakeholders communication.

Responsabilidades

• Full stack execution across web app (Next.js), API layer (TypeScript), browser extension, and integrations.
• Design APIs and data flows across Postgres, OpenSearch, DynamoDB, and S3; build background jobs and webhooks.
• Lead technical specs, review code, and communicate trade-offs to engineers and non-engineers.

Descripción del empleo

Senior Full Stack Engineer (AI) ships end-to-end features across our stack: database to frontend to integrations. You'll own work from spec to production, and you'll work alongside product, design, and our Australian engineering team. AI isn't a feature you'll add; it'sfoundational to how you think about what you build.

This is not a "full stack" role where you pick a layer and own it deeply. It's an ownership role where you move across the whole stack fluidly, making the calls that get features live fast and right. Reporting to the Engineering Lead, based in Melbourne (hybrid, flexible). ~75% hands-on execution: shipping features across web, API, browser extension, and integrations; building durable background jobs and webhooks; designing APIs and data flows across Postgres, OpenSearch, DynamoDB and S3; building AI-native features using Mastra, CopilotKit, and LLM APIs. ~25% strategy: technical specs, architecture decisions, code review rigour, and clear communication of trade-offs to engineers and non-engineers alike.

The candidate will have responsibilities across the following functions:

Feature shipping:

• Full stack execution: build and ship features across our customer web app (Next.js ), API layer (TypeScript), browser extension, and third- party integrations.
• Data and backend design: design APIs and data flows across Postgres (Supabase), OpenSearch, DynamoDB and S3; build durable background job syncs, bulk enrichment, scheduled jobs and webhooks.
• Quality standards: keep the codebase typed, tested, and observable; own code review and shipping discipline.

AI features:

• Agentic systems: build autonomous tools and copilots using frameworks like Mastra and CopilotKit.
• LLM integration: ship with Claude, OpenAI, and other LLM APIs; implement features like tool calling, RAG, agents, structured output and evaluations.
• CRM integrations: extend our integrations across HubSpot, Salesforce, and emerging integration platforms (Nango, Paragon).

Technical leadership:

• Specifications: write clear specs that explain trade-offs and scope.
• Collaboration: communicate technical decisions clearly to engineers and non- technical stakeholders; raise risks early.

Requirements:

• 5+ years shipping production web and Next.js : you've built real products end to end and shipped them at scale.
• Strong backend fundamentals: REST API design, relational data modelling in Postgres, auth and multi-tenancy patterns, background job architecture.
• Agentic AI hands-on: you've shipped features using LLMs (tool calling, RAG, agents, structured output, evals); you can explain what broke and how you debugged it.
• AI-native workflow: you use Claude Code, Cursor or similar as your default way of working, every day. You plan, delegate, review and verify AI output thoughtfully.
• Very good communication: clear written English in async updates, technical specs, and PR descriptions; confidence in conversations with stakeholders; you raise risks early.
• Ownership mindset: you take ambiguous problems through to shipped, measurable outcomes.
• You live and breathe AI tools. You use AI daily for API design, debugging, code review, test coverage, and architectural thinking as your default way of working, not a productivity experiment. In 2026, this is how strong engineers move fast, and you need to already be doing it.

Highly Valued:

• Monorepo experience: Turborepo or equivalent; Tailwind with Radix/Shadcn design systems; TanStack Query and Zustand.
• Authentication and billing: Clerk (organisations and RBAC), Stripe usage-based billing.
• AWS and infrastructure: Lambda, OpenSearch, DynamoDB, experience shipping at scale.
• Browser extensions: Plasmo or similar framework; Chrome extension patterns.
• Building MCP servers or evaluation and observability frameworks for agents.
• Startup or scaleup background where you've had to build the standard, not inherit it.