Senior Full-stack JavaScript Software Engineer (IC)

Location: Remote (Requires 4 hours overlap with Australia AEST)
Employment: Long-term contractor (full-time, 40h/w). You’ll invoice monthly; standard Net-14 terms.
Hiring entity: Testfully Pty Ltd (Australia).

Hey 👋

We’re a small, product-obsessed team building Testfully, the modern API Development Toolkit for enterprises. We’re hiring a Senior Full-stack JavaScript Software Engineer (IC), where about 90% of your time is spent on shipping features across our Web and Desktop apps, CLI, and code editor extensions. You’ll own work end-to-end—from crafting responsive React UIs to implementing well-structured JavaScript/TypeScript business logic.

The Opportunity: Build for developers, at scale

At Testfully, you’ll ship tools used worldwide and take on hard technical problems—fast UIs, reliable runtimes, and thoughtful DX—owning solutions end-to-end. If you enjoy hard problems and clean solutions, you want ownership and momentum, you’ll fit right in.

The Role: Make Developer Life Easier

You’ll spend ~90% of your time shipping product — roughly 70% business logic / 30% UI.

Build core product logic (TypeScript). Ship maintainable modules shared across Web, Desktop, CLI, and extensions using clear patterns and architecture.
Create reusable UI (React). Contribute to our design system (TypeScript, Radix UI, Tailwind) in an Nx monorepo.
Ship micro-frontends. Deliver Web/Desktop features using our design system, Akita (state) and RxJS (reactive flows).
Extend the CLI. Add features and keep parity with the apps via shared TypeScript packages.
Shape architecture. Partner with the CTO on decisions that guide how we build.

The Fit: Curious, Gritty, TypeScript-First, React-Savvy

You learn fast, love hard problems, work independently, and hold yourself accountable end-to-end. You turn ambiguity into shippable steps and communicate crisply. We expect the following technical competencies:

Fluent in JavaScript & TypeScript. Write clean, idiomatic code using modern patterns, best practices, and appropriate paradigms.
Expert in React. Shipped large-scale, stateful apps that solve complex business problems; strong in component design, performance, and accessibility.
Design systems. Built reusable component libraries with React and Tailwind CSS; think in tokens, composition, and maintainability.
Bonus. Experience with Rust, Golang, GraphQL, RxJS, or prior work on developer tools.

The Technology Stack: Modern, TypeScript-First

Testfully’s codebase is less than 5 years old, with a strong emphasis on maintainability, extensibility, and DX from day one. Our stack includes:

React 18 with TypeScript, Radix UI, Tailwind CSS, RxJS, and Nx monorepo for Web/Desktop apps and design system.
Tauri and Rust for the cross platform Desktop app.
Node.js, TypeScript for backend services and CLI.
GraphQL and Golang for our API backend.
AWS on a containerized architecture for scale and reliability.
Github for source control and GitHub Actions for CI/CD pipelines.
OpenAI Codex for AI-assisted development.

We live and breathe TypeScript, with 100% of our codebase in TS. We use modern patterns like reactive programming with RxJS, atomic design for UI, and modular architecture for business logic. We prioritize DX, performance, and accessibility.

AI at Testfully: Human-Led, AI-Accelerated

AI is an enabler, not a replacement. We build with OpenAI Codex in the loop—today, 100% of new features use AI for coding, tests, docs, and exploration—while human judgment and ownership decide what ships. You’re expected to leverage AI daily, then apply your expertise to refine, verify, and be accountable for outcomes.

We also push back hard on low-quality outputs:

No AI slop. Reject or rewrite weak suggestions; keep code readable and type-safe.
Design > autocomplete. Don’t accept choices that harm DX, performance, accessibility, or API clarity.
Proven code only. Ship with meaningful tests, docs/migrations, and profiling where it matters.

If you’re not excited to use AI and stand behind the result, this role isn’t a fit.

When This Role Isn’t a Fit

Hands-off approach. Early-stage startup = everyone ships, debugs, documents, and helps shape the product. No bystanders.
Low tolerance for ambiguity. Priorities shift. You’ll need to self-direct, make calls with incomplete info, and adapt quickly.
Avoids direct feedback. We use real-time, candid feedback to move fast and raise quality—always with respect and care.

The Company: Small, Product-Obsessed, Developer-First

We’re a small, tight-knit team of passinate builders from Sydney, Australia. Our founder is a software engineer turned entrepreneur. Our obsession over our product and the problem we’re solving is what drives us. Today, we serve governments, fortune 500s, and fast-growing startups worldwide. We’re profitable and growing fast, and we compete with the likes of Postman and Kong Inc, and we’re winning against them left and right.

Our customers love us because we obsess over their needs, and we move fast to solve their problems. We’re not a “me too” product; we’re building something different, something exceptionally good, and we’re looking for new teammates who share our passion.

How to Apply

Email matt@testfully.io with subject: Senior Full-stack JavaScript Software Engineer (IC).
Attach:
- Your latest resume (PDF)
- A short cover note with relevant experience and expected monthly rate.
- (Optional) links to GitHub/portfolio/OSS

Our founder will personally review all applications, and respond within a week.