Senior Frontend Engineer

Arlq; Paris; Hybride; EUR 90 000 - 130 000; Plein temps

Avantages offerts par ce poste

Equity stake

On-site in central Paris

Résumé du poste

Arlequin in Paris seeks a senior frontend engineer to own the quality and consistency of the user experience across the HUDEX platform, delivering advanced data visualizations and complex interfaces.

You’ll collaborate with product and a future senior Product Designer, and represent the frontend voice in architecture decisions with the Head of Engineering. You will progressively take ownership of the design system and cross-product patterns.

Qualifications

• 5+ years of frontend experience, including data-driven products.
• Strong command of React and its modern ecosystem.
• Real product and UX sensitivity; able to challenge a design.
• Experience with data visualization (D3, graph libraries, Plot).
• Professional English

Responsabilités

• Own the quality and consistency of the user experience across the HUDEX platform.
• Collaborate with product and a future senior Product Designer.
• Represent the frontend voice in architecture decisions with Head of Engineering.
• Progressively take ownership of the design system and cross-product patterns.

Connaissances

React

TypeScript

Data visualization

UX sensibility

Professional English

Outils

Tanstack Router

Query

observablehq/plot

d3

react-intl

FormatJS

Hono

Drizzle

OpenAuth

Description du poste

Own the quality of the user experience: analysis interfaces, complex data visualizations and cross-product frontend patterns.

5+ years of experience

Full-time

On-site in Paris

About Arlequin

Arlequin is building the sovereign European alternative to Palantir: an AI platform capable of processing massive data volumes without bias, with high-impact use cases such as fighting disinformation. Founded in late 2024 by Hugo Micheron (researcher in geopolitics and systemic risk) and Antoine Jardin (CNRS research engineer).

The role

You’ll own the quality and consistency of the user experience across the HUDEX platform — analysis interfaces, complex data visualizations (knowledge graphs, time series, narrative dynamics), user journeys for creating projects and data collections. Our users are non-technical analysts handling massive datasets and AI outputs: interface quality is one of the key factors that makes the difference between contracts that renew and those that don’t. Your business impact is direct.

You’ll work hand in hand with product and a future senior Product Designer, represent the frontend voice in architecture decisions alongside the Head of Engineering, and progressively take ownership of the design system and cross-product patterns.

Stack

Core : React 19, TypeScript, Tanstack Router + Query

Visualization: @observablehq/plot, d3, in-house graph library

i18n : react-intl + FormatJS, workflow English/French

Backend interfacing: Hono, Drizzle, OpenAuth

What we’re looking for

5+ years of frontend experience, including at least 2 on data-driven products or complex interfaces

Strong command of React and its modern ecosystem

Real product and UX sensitivity — able to challenge a design to make it better

Experience with data visualization (D3, graph libraries, Plot, or equivalent)

Professional English

Bonus

Ownership of, or significant contribution to, a design system

Early/mid-stage startup experience

Mastery of agentic coding tools and code models

Interest in emerging tools and paradigms

Process (~2 weeks)

Screening (15 min)

Fit interview (30 min)

Technical interview (1h)

Founder culture fit (45 min)

Reference calls

Offer

Package

• Competitive compensation including equity stake

On-site central Paris