Freelance Fullstack Engineer React / Node.js - Freelance

Collective.work; Madrid; On-site; EUR 65,000 - 111,000; Part time

Job summary

Collective.work in Madrid is seeking a freelance software engineer to build features on the React frontend and Node.js backend, integrate AI APIs, and connect ATS tools. You will collaborate with product and engineering teams to deliver scalable, reliable code from concept to production.

This onsite role in Madrid offers flexible start dates and contract terms, with day-rate-based compensation and freelance/contract conditions.

Qualifications

• Freelance/contract software engineer with strong frontend and backend skills.
• Experience delivering features across React frontend and Node.js backend.
• Ability to integrate AI APIs and ATS platforms.

Responsibilities

• Build and ship product features across the React frontend and Node.js backend.
• Develop scalable APIs, backend services, and integrations with third-party tools, including ATS platforms.
• Integrate AI-powered capabilities into intuitive, high-performance user experiences.
• Improve application performance, reliability, and code quality.
• Collaborate closely with product and engineering teams to deliver features from conception to production.

Tools

React

Node.js

JavaScript/TypeScript

AI APIs

ATS integrations

Job description

Context

Collective.work is building the next generation of AI-powered recruitment. The company supports over 20,000 recruiters and headhunters across France, Belgium, Spain, and EMEA, and is expanding its product and distribution in the UK. The platform combines a suite of AI agents — from sourcing and outreach to job posting and ATS integrations — with a database of 800M+ professional profiles and a network of 1M+ active candidates.

Missions

• Build and ship product features across the React frontend and Node.js backend.
• Develop scalable APIs, backend services, and integrations with third-party tools, including ATS platforms.
• Integrate AI-powered capabilities into intuitive, high-performance user experiences.
• Improve application performance, reliability, and code quality.
• Collaborate closely with product and engineering teams to deliver features from conception to production.

Tools & Environment

• React
• Node.js
• JavaScript/TypeScript
• AI APIs and LLM integrations (plus)
• ATS platform integrations

Working Conditions

• Location: Madrid, Spain
• Type: Freelance / Contract
• Start date: ASAP
• Duration and day rate: To be agreed