Front-End Developer (Full-Time, Remote)

Horizon Assset Investments

Front-End Developer (Full-Time, Remote)

We are seeking a Front-End Developer to design and build the user-facing components of our high-performance trading platform. You will play a key role in creating intuitive, data-rich interfaces that enable traders and analysts to work efficiently and effectively.

You will collaborate closely with the Back-End Development Team and the Project Manager to deliver seamless, integrated systems. A key factor is the front end developer’s ability to deeply discuss approaches, trade-offs, limitations, and pros/cons with the development team, rather than reliance on any specific pattern or library.

Key Responsibilities

  • Develop and maintain the front-end applications of our trading platform.
  • Collaborate with back-end developers and the project manager to ensure smooth integration across systems.
  • Design and implement multi-page layouts, menus, and workflows that balance usability with efficiency.
  • Contribute to the design and user experience of the trading platform, performance & risk manager, and backtesting engine.
  • Implement and optimize charting and data visualization features, leveraging libraries such as TradingView or D3.js to support a wide variety of chart types (tables, multi-line chart packs, etc.).
  • Continuously refine the UI/UX to ensure clarity, speed, and intuitive navigation for end users.

Qualifications

  • Strong communication skills and the ability to collaborate effectively with developers, project managers, and business stakeholders.
  • A keen eye for design, simplicity, and efficiency, with the ability to translate complex requirements into clean, user-friendly interfaces.
  • Knowledge of financial systems or trading concepts is preferred.

Core stack (mandatory)

  • React 18 + Next.js (App Router), TypeScript, TailwindCSS.
  • Strong command of state management for high-frequency data (e.g., Zustand, Redux Toolkit, useSyncExternalStore).

Real-time data & performance

  • Hands-on with WebSockets / SSE and reconnection/backoff strategies; handling authenticated socket connections and topic resubscriptions.
  • Experience implementing backpressure, buffering, coalescing, and windowing to prevent UI thrash under thousands of updates/minute.
  • Data virtualization (react-virtualized, react-window) for large tables (orders, positions, trades).
  • Familiar with Web Workers / OffscreenCanvas and message passing to keep the main thread responsive.
  • Awareness of latency budgets and frame-time profiling using React DevTools and browser performance tools.

Charting & visualization

  • Practical experience with professional charting libs (e.g., TradingView Charting Library, Lightweight Charts, Highcharts, D3).
  • Real-time overlays: best bid/ask, order book depth, last OHLCV, order/position annotations.
  • Multi-pane layouts (price, volume, indicators) with synchronized crosshairs and time scales.

Architecture & data access

  • Client-side caching and invalidation (e.g., TanStack Query / React Query).
  • Schema-driven UI for instruments and venues.
  • Use of Error Boundaries, Suspense, and progressive hydration/streaming for large Next.js pages.

Auth, security, and roles

  • Strong understanding of OIDC/JWT flows, token refresh/rotation, and WebSocket authentication.
  • Role-based feature gating (read-only vs trading permissions).

Testing, quality, and reliability

  • Unit tests for critical transforms/parsers (e.g., Playwright/Vitest for E2E/interaction flows)
  • Experience with feature flags, staged rollouts, and monitoring with Sentry/OpenTelemetry.

Nice-to-haves

  • Experience with desktop-class layouts (drag-to-dock panels, resizable grids).
  • Exposure to WASM for heavy computations (e.g., indicator calculations).
  • Familiarity with FIX/crypto venue nuances (tick sizes, lot sizes, trading sessions).

Screening Questions
Keep answers 4–8 sentences each. Bullet points allowed if clear.

  1. UI migration (hrzk → Next.js):

Pick ONE area from the provided hrzk.html (e.g., Orders+Trades, Positions table, Equity/Drawdown).

Explain how you’d migrate it to **React 18 + Next.js (App Router) + TypeScript

  • Tailwind**.

Include folder structure and what you’d make client vs server components.

(We care about your trade-offs, not “the one true way”.)

  1. Real-time data ingestion:

Describe how you’d handle WebSockets/SSE for high-frequency updates:

reconnect/backoff, authenticated sockets, and topic resubscriptions.

What failures do you expect in production?

  1. Backpressure + UI thrash prevention:

Assume thousands of updates/minute for orders/positions/trades.

Explain how you’d implement buffering/coalescing/windowing so the UI stays responsive.

Mention how you’d combine this with state management (e.g., Zustand/RTK/useSyncExternalStore) and virtualization (react-window / react-virtualized).

What would you measure to prove it works?

  1. Charting approach:

We need fast, readable, data-rich charts (equity/drawdown, doughnut/bars, etc.).

Pick a chart type from hrzk.html and explain:

- which charting library you’d choose (TradingView Lightweight Charts / Highcharts / D3 / etc.)

- update frequency strategy

- performance risks + mitigations

  1. Auth + role gating:

Explain how you’d handle JWT/OIDC token refresh and WebSocket authentication, then implement role-based gating (read-only vs trading).

Use an example like “Cancel All Orders” or “Stop/Start Execution”: when do you hide vs disable vs show a warning?

  1. Remote ownership + teamwork:

Give one example where you took ownership remotely on an ambiguous task.

Then describe how you’d work with a small dev team: how you ask clarifying questions, communicate risk early, and avoid shipping “local optimum” code that breaks other parts of the system.

What to expect (our interview process):

Our hiring process is mostly async and focused on real work.
You’ll start with a CV submission and a short, structured application.
Shortlisted candidates complete an async technical screen.
Finalists complete a paid, time‑boxed work sample aligned to the role.
End‑to‑end, the process typically runs 4–6 weeks.

FAQs

· Do I need to respond to the questions?

Yes, please respond to the questions ideally in an open format via a cover letter. This is mandatory for vetting.

· Do I need to attend live interviews?
Most stages are async to reduce scheduling friction. Live calls are minimal.

· Do I need to be on camera for the sample work?
No — screen + voice is sufficient.

· What tools can I use to submit recordings?
Any common screen‑recording or file‑sharing tool is fine, as long as the video is easy to view.

· Is the final task paid?
Yes. Final shortlisted candidates complete a paid, time‑boxed work sample.