Software Engineer - Frontend - React

This role is suitable for a Senior Frontend Software Engineer with 4+ years of experience in React or Angular and strong English communication skills.

The candidate should be skilled in databases, REST or GraphQL API design, microservices, event-driven architectures, testing, and technologies such as React, Rails, PostgreSQL, GCP, and BigQuery.

They should be familiar with building polished developer-focused interfaces, owning projects independently, improving engineering workflows through automation, collaborating with product and marketing teams, and contributing to open-source or technical communities.

How would you design a React component architecture for a data-intensive dashboard with reusable filters, tables, and charts?

I would separate presentational components from data-fetching and state-management concerns, then build reusable primitives for filters, pagination, tables, and visualizations. I would also define clear TypeScript or PropTypes contracts and keep domain-specific logic in custom hooks or dedicated modules.

How would you manage GraphQL data fetching and caching in a React application?

I would use a GraphQL client with normalized caching, query variables, and explicit loading, error, and empty states. Mutations should update or invalidate affected cache entries, while pagination and polling should be handled consistently through reusable hooks.

What are the main differences between REST and GraphQL, and when would you choose GraphQL?

REST exposes resource-oriented endpoints, while GraphQL lets clients request exactly the fields and relationships they need through a typed schema. GraphQL is particularly useful for complex reporting interfaces that aggregate data from multiple backend services.

How would you optimize the performance of a React interface displaying large engineering datasets?

I would use server-side filtering, sorting, and pagination, along with list virtualization when many rows must be rendered. I would also profile rendering, memoize only expensive computations, avoid unnecessary state updates, and use code splitting for large feature areas.

How would you design frontend error handling for unreliable API or microservice responses?

I would distinguish recoverable errors, validation errors, authorization failures, and system failures, presenting each with an appropriate user-facing message. The UI should support retries and partial results where possible, while logging structured diagnostic information for troubleshooting.

How can a React frontend work effectively with event-driven microservices?

The frontend should consume stable API or GraphQL contracts rather than depending directly on internal service boundaries. For asynchronous operations, it can use polling, subscriptions, or server-sent events to reflect processing status and update the UI when events are completed.

What database considerations matter when building reporting features backed by Postgres and BigQuery?

Postgres is generally suited to transactional application data, while BigQuery is better for large-scale analytical queries. I would ensure that reporting queries are aggregated efficiently, use appropriate indexes or partitioning, and avoid exposing expensive analytical operations directly to interactive requests.

How would you test a React feature using a test-driven development approach?

I would first define the expected user behavior, then write tests for rendering, interactions, loading states, errors, and accessibility before implementing the feature. I would combine unit tests for isolated logic with integration tests that verify components working with mocked GraphQL or API responses.

How would you make a data visualization accessible and usable for developers with different needs?

I would provide semantic labels, keyboard navigation, sufficient color contrast, and text or tabular alternatives for chart data. Important insights should not rely on color alone, and loading, empty, and error states should be clearly communicated to assistive technologies.

How would you approach delivering a frontend project autonomously from discovery through deployment?

I would clarify the user problem and success criteria, propose a solution with product and design stakeholders, break it into incremental deliverables, and validate assumptions early. I would then implement and test the feature, automate quality checks in the delivery pipeline, monitor its behavior, and iterate based on user feedback.

Keypup is a fast-growing, developer-first company building data-driven intelligence tools that help engineering organizations gain clarity and recognition. As a Frontend Software Engineer, you’ll create polished React experiences, own projects end to end, and contribute to APIs, data flows, automation, and microservice-based systems. You’ll work with React, Ruby on Rails, GraphQL, PostgreSQL, GCP, BigQuery, and Cloudflare in a fully flexible La Rochelle or remote environment. Salary is not specified. Apply for the autonomy, meaningful early-stage impact, collaborative culture, and opportunity to shape a product built by engineers for engineers.