Senior / Staff AI-First Fullstack Engineer

About TFX

We help Americans living abroad file their US taxes — a niche we've been refining for over a decade. Today we serve thousands of expats in 190+ countries and we're scaling fast: double-digit % growth in 2025 and 2026, and a goal to double the business in the next 3–4 years.
Our software is a primary driver of an excellent client experience, and enables growth and efficiency in marketing, sales, and operations. We invest heavily in modern tooling, including AI: the team uses Claude Code, and custom agents as part of the daily workflow, not as a curiosity.

The Role

We're hiring a Senior or Staff fullstack engineer who treats AI as a daily productivity multiplier. You'll ship product features on a mature Rails 8 + Vue 3 codebase, raise the bar of an experienced dev team, and help us extend our internal AI agent infrastructure.
This is an Individual Contributor role — no formal team management, but high technical influence.

What you'll do

• Ship product features end-to-end on Rails + Vue — from data model to UI — at a weekly release cadence.
• Use AI as your primary way of writing code: decompose tasks so an agent closes them in one or two passes, review AI-generated diffs critically, parallelize across sessions deliberately.
• Raise the team's bar through code reviews, agent design patterns, and internal documentation — by example, not by mandate.
• Modernize legacy areas of a large codebase — refactor outdated patterns, retire dead code, contribute to ongoing Rails version upgrades.
• Extend our internal AI tooling: contribute to the team's library of agents, MCP integrations, and custom workflows.

You're a strong fit if you have

• 5+ years of commercial fullstack experience (Senior) or 8+ years (Staff).
• 2+ years of production Ruby on Rails as a primary stack — not side experiments.
• Confidence in Vue 3 (Composition API, single-file components) — you can be productive without a long ramp-up.
• AI integrated into your daily workflow. You use Claude Code, Cursor, Aider, or Copilot as your primary way of writing code, not as an occasional helper.
• Hands-on experience building LLM agents — tool use / function calling, multi-step workflows, output validation, guardrails. Not as a research project — as something you've shipped.
• Experience code-reviewing AI-generated pull requests in a team setting — you can tell a good AI-authored diff from a bad one, and give constructive feedback on a colleague's AI output.
• A shipping mindset. You can name the last few things you put into production and the impact they had.
• High agency and parallel-pathing instincts. You keep multiple threads moving, surface blockers early, and don't wait for a detailed spec to start.
• Right to work in your country of residence. We don't sponsor visas.

Nice to have

• TypeScript experience in a Vue 3 codebase.
• Domain experience in fintech, accounting, or tax.
• MCP servers, custom Claude/Cursor skills, or open-source agentic projects — anything that demonstrates you've gone past "user" into "builder" with AI.
• Experience modernizing legacy Rails codebases — major version upgrades, large refactors without breaking production.
• Observability experience with Sentry, AppSignal, or similar.

What we offer

• Fully remote work, any timezone with reasonable overlap with EU and US East.
• Competitive USD compensation (discussed on the recruiter screen) — band depends on level.
• A mature codebase with real domain depth.
• A team that takes AI tooling seriously — not as a gimmick, not as a fad.
• A growing, profitable company with a clear runway and a real product market fit.
  
  

Hiring process

1. Recruiter screen (30 min)
2. Technical conversation with the CTO (90–120 min) — your background, AI workflow, recent shipped work.
3. Live AI coding session (60–90 min) — a realistic task on a sample repo, using your AI tools of choice.
   
   
   

Apply with resume and interest note to victoria.luna@tfx.tax
We appreciate your interest and advise that only those selected for an interview will be contacted