Backend Engineer for AI Integration

Location: Madrid Office About Aircall Aircall builds an AI-driven customer communications platform used by over 22,000 businesses worldwide. Our product brings together voice, SMS, WhatsApp, and AI features in a single workspace, helping teams boost revenue, resolve issues faster, and scale their operations efficiently. Headquartered in Paris, Aircall has a strong global footprint with offices in Seattle, Madrid, London, Berlin, San Francisco, New York City, Sydney, and Mexico City. Our company is growing quickly, supported by leading investors and advances in AI across our product lines. Our Culture We focus on customer satisfaction, data-driven decisions, and meaningful results. Team members are encouraged to take ownership, keep learning, and act quickly but thoughtfully. Collaboration, trust, and impact shape our daily work. About the New Product Unit Aircall is launching a New Product Unit dedicated to advancing autonomous sales. The team is building an AI Orchestration Layer that records and understands customer interactions across calls, video, email, and WhatsApp. This system will automate sales workflows such as CRM updates, follow-ups, task creation, and coaching insights. Our long-term vision is a self-optimizing Sales OS powered by specialized AI agents working together to improve revenue processes. Role Overview: Senior Backend Software Engineer (Python) This position calls for an experienced backend engineer with strong Python skills, ready to work beyond traditional backend boundaries. The role suits someone who values both clean architecture and practical progress, and who can balance high-quality work with the need for speed in a startup setting. What You Will Do Tackle complex technical challenges, including distributed systems, AI orchestration, architecture, performance, and scalability Contribute to the design and implementation of backend systems for the AI Orchestration Layer Work closely with product and engineering teams to deliver new features Iterate quickly, shipping solutions and learning from feedback Who Will Thrive Engineers who enjoy solving difficult problems and making architectural decisions Those who can dive deep into technical details while keeping an eye on rapid delivery People who take pride in their work and appreciate the pace of a growing company

Join Aircall, a unicorn and AI-driven customer communications platform, serving over 22,000 companies globally. We are innovating the way businesses communicate by seamlessly integrating voice, SMS, WhatsApp, and AI into a unified workspace.Our growth stems from a straightforward principle: empower teams to work more efficiently. Our AI Voice Agent automates routine calls, AI Assist enhances post-call tasks, and AI Assist Pro provides real-time support, enabling individuals to excel in their roles. This leads to increased revenue, quicker resolutions, and confident team scalability.With headquarters in Paris and a robust North American presence in Seattle, alongside teams in Madrid, London, Berlin, San Francisco, New York City, Sydney, and Mexico City, we have developed a beloved product and a rapidly expanding business, supported by top-tier investors and driven by swift AI advancements across various product lines.At Aircall, you will be part of a dynamic organization. We are ambitious, focused on product excellence, and committed to execution, ensuring visible impacts, quick decisions, and genuine growth.Our Work Culture: We are deeply customer-focused, data-informed, and dedicated to delivering significant outcomes. We prioritize ownership, ongoing learning, and a thoughtful pace. If you thrive in a collaborative, fast-paced setting where trust and impact are key, you will feel right at home here.Role Overview:As a Senior Backend Software Engineer, you will play a crucial role in designing, developing, deploying, and maintaining essential features that enhance customer value through voice integration.You will be expected to advocate for best practices and provide mentorship within your team and across the engineering department.We are driven by quality, excellence, and agility, and you will contribute to elevating these standards.Utilizing a diverse range of backend technology stacks, tailored to meet specific needs and consistently hosted on AWS, we create resilient services that add value to voice integration and seamlessly connect with our clients' critical business tools such as CRM, Helpdesk, E-Commerce, and more.

Join Adyen as an Integration Engineer! At Adyen, we empower businesses with a comprehensive suite of payment, data, and financial solutions, serving renowned clients like Meta, Uber, and LVMH. Our platform is engineered for ambition, allowing businesses to thrive in a competitive landscape. We foster an environment where our team members can excel, supported by a culture that encourages ownership over their careers. Our motivated individuals tackle unique technical challenges collaboratively, delivering innovative and ethical solutions to help businesses achieve their goals more efficiently. About the Role: We are seeking an Integration Engineer with a robust background in technology, integration design, and project management, coupled with a strong merchant focus. You will serve as the primary technical contact for our merchants, guiding them through the design, development, testing, and launch phases of their integrations with Adyen's platform, ensuring a top-notch merchant experience throughout the project lifecycle. This role offers the chance to work on a variety of projects involving diverse payment solutions, including e-commerce platforms, marketplaces, and card issuing programs. By leveraging your technical skills and business insights, you will play a crucial role in facilitating a seamless implementation process and maintaining effective communication with both our merchants and internal teams. This position is based in our Madrid office, and we are looking for candidates who are both consultative and technical. Your Responsibilities: Utilize your development and programming expertise to design scalable and effective solutions for merchant integrations, adhering to payment best practices. Act as a consultative partner in various sectors like e-commerce and point of sale, guiding merchants through integration processes. Collaborate with Sales, Account Managers, Product, and Engineering teams to provide seamless merchant experiences and drive ongoing enhancements. Employ project management and technical consulting skills to ensure high-quality project delivery, maintaining the technical integrity of merchant integrations. Offer insights on optimizing payment solutions, including checkout experiences and omni-channel payments, while working alongside Developers and Product Managers to improve the platform.

Groupon is a dynamic marketplace that connects customers with exciting experiences and services, empowering local businesses to thrive. Having partnered with over a million merchants worldwide, we facilitate connections for 16 million customers seeking deals across diverse categories. In a world dominated by e-commerce giants, we pride ourselves on being a platform genuinely committed to the success of local businesses through performance-driven strategies.At Groupon, we are on an ambitious journey to transform our operations with a relentless focus on achieving results. Despite our global presence with thousands of employees, we uphold a culture that fosters innovation, encourages risk-taking, and celebrates success. Here, your impact can be immediate, as we operate on a scale that allows for rapid transformation. We embody a "best of both worlds" philosophy—large enough to offer robust resources, yet small enough for individuals to wield significant autonomy and make a meaningful impact.About the RoleJoin our CoreApps Platform team, the backbone of Groupon's engineering efforts responsible for the global commerce engine. Our platform manages every customer interaction and transaction on a worldwide scale. In this high-impact, senior-level Individual Contributor (IC) role, you will focus on ensuring KTLO stability at massive scale while advancing a significant platform modernization initiative through an AI-first approach.You will take ownership of mission-critical services that handle over 100,000 Requests Per Minute (RPM) and drive the transition from legacy Java/Ruby systems to a modern TypeScript/Node.js microservices architecture, utilizing cutting-edge AI coding tools to achieve unmatched speed and quality.

As a Senior Backend/Platform Engineer at causaprima, you will be responsible for the foundational platform utilized by our agents. Your expertise will enhance our event-driven architecture, streamline data pipelines, integrate with customer accounting systems, and ensure that our infrastructure is reliable, auditable, and efficient.Key ResponsibilitiesEvent Store Management — Design and maintain an append-only PostgreSQL database featuring tamper-evident hash chaining, real-time event distribution, agent replay, recovery capabilities, and schema versioning.Cryptographic Signature Infrastructure — Establish key management and signature verification systems for all agent events while implementing approval chains for external actions.Workflow Constraint Engine — Develop a gateway to verify authorization for any external actions including emails, payments, or API calls.PII Vault & GDPR Compliance — Create isolated, encrypted storage solutions for personal data, ensuring compliance with the right to erasure and data residency requirements.Multi-Tenancy Management — Implement row-level security and tenant isolation across all data stores, including tenant-scoped LLM API keys.Authorization Framework (Cerbos) — Utilize attribute-based access control for both agents and humans, ensuring deterministic policy evaluation where LLMs do not make authorization decisions.MCP Security Layer — Develop authentication, capability-based scoping per partner, and rate limiting for the Model Context Protocol endpoint.Database Architecture — Focus on PostgreSQL schema design, indexing strategies, performance tuning, and read replica topology.

Join Aircall as a Senior Backend/Platform Engineer, where you will play a crucial role in enhancing our platform's infrastructure and backend systems. You will collaborate with cross-functional teams to design and implement scalable solutions that ensure seamless communication for our users. If you are passionate about crafting high-performance systems and thrive in a dynamic environment, we would love to hear from you!

Managing corporate spending can often be a challenging endeavor, with convoluted processes that hinder efficiency for finance teams and employees. At Pleo, we are revolutionizing this process. We provide financial solutions designed to simplify money management, making it seamless and remarkably efficient for everyone involved. Our mission is to empower businesses to 'go beyond' traditional spending methods.The name 'Pleo' translates to 'more than you’d expect', and this philosophy has underpinned our success over the last decade.We find ourselves at a crucial juncture in our growth; every decision we make impacts over 40,000 customers and is vital to our mutual success. We seek individuals who are committed to understanding customer needs, transforming complex challenges into straightforward solutions, and questioning the status quo—all while aiming high. With ambitious goals propelling us forward, we embrace the journey of discovery and innovation. Our team consists of over 850 talented individuals representing more than 100 nationalities, all dedicated to shaping the future of business spending.About the RoleWe are in search of a Senior Backend Engineer to join our dynamic team at Pleo. In this role, you will play a key part in developing and scaling our backend systems while engaging in exciting projects as we enhance our product and service offerings. If you are passionate about tackling complex technical challenges and thrive in a culture that prioritizes transparency, collaboration, and innovation, this position is made for you.Your ResponsibilitiesAs a Senior Backend Engineer, you will:Lead the design, development, and maintenance of scalable microservices primarily using Kotlin.Collaborate with cross-functional teams to create innovative solutions across various domains including Platform and Services.Analyze system performance and implement optimizations to ensure high reliability and scalability.Participate in code reviews, conduct post-mortems, and mentor fellow engineers.Proactively address technical debt and guide the team through technical challenges and migrations.QualificationsYou will excel in this role if you possess:Strong expertise in server-side programming, particularly in Kotlin, and experience with distributed systems, microservices, and various cloud environments such as AWS and Kubernetes.Proficiency in relational databases such as PostgreSQL, testing frameworks (e.g., JUnit, Testcontainers), and observability tools like Grafana.

airapps is looking for a Backend DevOps Engineer based in Madrid. This position focuses on improving development workflows and supporting reliable application deployments. Role overview The Backend DevOps Engineer will work with both development and operations teams. The main goal is to make development processes smoother and ensure that applications are deployed efficiently. What you will do Collaborate with team members to implement continuous integration and continuous deployment (CI/CD) pipelines Manage and maintain cloud infrastructure Work to improve system performance and reliability Location This role is based in Madrid.

Join Us in Shaping the Future of Aerospace Technology!As a UAV Avionics and Systems Integration Engineer at Destinus, you will be at the forefront of revolutionizing the defense industry with pioneering technologies. Picture yourself in a hangar filled with advanced hydrogen-powered UAVs, moving at hypersonic speeds and operating at the edge of space. You are not merely following protocols—you are the architect of their operational framework. Your expertise in avionics, sensors, power systems, and flight controls is essential for creating a harmonious integration that pushes the boundaries of speed and efficiency. Every wire you connect, interface you configure, and test you conduct contributes to the autonomous performance of UAVs soaring through the stratosphere with unparalleled precision.At Destinus, we partner with government agencies and defense organizations worldwide, providing innovative solutions for mission-critical operations. Our commitment to efficiency and technological superiority positions us as leaders in aerospace advancements. Be part of our mission to redefine what speed means globally!

Role overview Celonis is looking for a Senior Engineer in Workday Integration & Automation based in Madrid, Spain. The position focuses on improving how Workday connects with other systems and developing automation that supports business operations. What you will do Refine and optimize integration processes for Workday systems Create and improve automation solutions to increase operational efficiency Collaborate with teams across the company to design and implement integration strategies aligned with business objectives

Role Overview airapps is hiring a Backend QA Engineer based in Madrid. This position focuses on quality assurance for backend systems, helping to keep applications reliable and up to standard. What You Will Do Support QA processes for backend applications Work closely with team members to identify and resolve issues Help ensure applications perform as intended and meet quality expectations Who We’re Looking For Detail-oriented approach to testing and problem-solving Comfortable working within a collaborative team Motivated to deliver solid, dependable software Location This role is based in Madrid.

fiskaly develops technology that secures digital receipts and ensures legally compliant transactions for millions of users each day. By applying digital signatures, the company helps prevent tax fraud and supports merchants with a streamlined, paperless solution. The team is dedicated to simplifying receipts for everyone. Role overview This Senior Backend Engineer (Golang) position is a full-time, permanent role open to candidates based in or near Vienna, or within a two-hour time zone difference. The company is not considering freelancers for this role. What you will do Serve as a System Architect within a focused squad, developing API-first SaaS products. Lead backend development using Golang and other object-oriented languages, contributing throughout the software lifecycle. Apply modern tools, including AI coding assistants and automation, to minimize repetitive tasks and tackle complex problems. Design, build, and maintain distributed systems for fiskaly's fiscalization platform. Shape the architecture and scalability of the unified digital receipts interface. Requirements Minimum 5 years of backend development experience, with a strong background in Golang and object-oriented programming. Fluency in both German and English. Located in or near Vienna, or within a two-hour time zone difference. Available for full-time employment (no freelance contracts). Salary and contract Gross annual salary: €45,000 – €70,000 Full-time, permanent position

We are seeking a talented Integration Engineer PM&T to join our dynamic team in the aerospace sector. In this role, you will be responsible for ensuring the successful integration of various systems and components within aerospace projects. You will collaborate with cross-functional teams and contribute to innovative solutions that enhance operational efficiency.

Managing expenses shouldn’t be a headache. At Pleo, we’re revolutionizing the way businesses handle spend management by creating solutions that simplify financial processes for both finance teams and employees. Our goal is to empower organizations to 'go beyond' traditional methods.Since our inception 10 years ago, we’ve embraced the philosophy of ‘Pleo’, meaning ‘more than you’d expect’, which has been pivotal to our success.We are currently at a significant juncture in our growth journey; every decision we make affects our more than 40,000 customers, our business, and our collective achievements. We are looking for individuals who take pride in identifying customer needs, transforming complex challenges into straightforward solutions, and respectfully challenging the status quo. With our ambitious goals ahead, we are a dynamic and diverse team of over 850 individuals from more than 100 nationalities, dedicated to shaping the future of business spending.About the RoleWe are seeking a skilled Backend Engineer to join our innovative team at Pleo. In this position, you will play a crucial role in building and scaling our backend systems, engaging in exciting projects as we expand our product and service offerings. If you are passionate about solving intricate technical challenges and thrive in a culture that values transparency, collaboration, and innovation, we invite you to apply.What You’ll Be DoingAs a Backend Engineer, your responsibilities will include:Designing, building, and maintaining scalable microservices primarily using Kotlin.Collaborating with cross-functional teams to develop innovative solutions across various domains such as Platform, Services, and SMB.Analyzing system performance and implementing optimizations to ensure high reliability and scalability.Participating in code reviews and post-mortems while mentoring fellow engineers.Proactively addressing technical debt and guiding the team through challenges and migrations.What You BringThis role is ideal for you if you possess:Experience in server-side languages, particularly Kotlin, along with expertise in distributed systems, microservices, and cloud environments (e.g., AWS, Kubernetes).Proficiency with relational databases such as PostgreSQL and familiarity with testing frameworks (e.g., JUnit, Testcontainers).

At Datadog, we are revolutionizing how engineers monitor, secure, and scale their infrastructure and applications, driving reliability and performance for thousands of businesses. We process trillions of data points daily and address challenges related to scale, speed, and resilience. We are in search of seasoned backend engineers eager to take charge of vital services and enhance their expertise in distributed systems. If you have experience in building APIs, data pipelines, or backend tools, this position offers an opportunity to expand your influence while mastering the design and operation of high-scale, high-availability systems that underpin observability and security solutions utilized by engineers globally. At Datadog, we cherish our office culture—the relationships it fosters, the creativity it encourages, and the teamwork it cultivates. We embrace a hybrid work model, empowering our employees to achieve a work-life balance that suits them best.

Managing expenditures can be a complex and cumbersome task, but at Pleo, we're revolutionizing this space. Our innovative spend management solutions empower finance teams and employees to handle their finances effortlessly and effectively. With a mission to help businesses 'go beyond', we strive to simplify the way money is managed.Over the past decade, our mantra 'Pleo'—meaning 'more than you’d expect'—has driven our success and innovation.As we continue to expand our reach to over 40,000 customers, we seek individuals who are passionate about identifying customer needs, simplifying complex challenges, and ambitiously pursuing excellence. Join our diverse team of 850+ exceptional individuals from more than 100 nationalities, all committed to shaping the future of business spending.About the RoleWe are excited to invite a skilled Backend Engineer to our team at Pleo. In this pivotal role, you will contribute to the design and scalability of our backend systems while taking part in exciting projects as we enhance our product and service offerings. If you have a passion for tackling complex technical challenges and desire to work in an environment that values transparency, collaboration, and a strong commitment to innovation, this opportunity is for you.Your ResponsibilitiesAs a Backend Engineer, you will:Design, develop, and maintain scalable microservices primarily using Kotlin.Collaborate with cross-functional teams to create innovative solutions across various domains, including Platform, Services, and SMB.Evaluate system performance and implement optimizations to ensure reliability and scalability.Engage in code reviews, conduct post-mortems, and mentor junior engineers.Proactively manage technical debt and navigate the team through technical challenges and transitions.Your QualificationsTo excel in this role, you should possess:Proven experience in server-side programming languages, particularly Kotlin, alongside expertise in distributed systems, microservices, and cloud environments (e.g., AWS, Kubernetes).Strong proficiency with relational databases such as PostgreSQL, testing frameworks (e.g., JUnit, Testcontainers), and observability tools like Grafana.

About the Role airapps is looking for a Backend Engineer in Madrid to help shape the systems behind our platforms. This role centers on building and improving backend architecture that supports our applications. What You Will Do Design, implement, and maintain scalable backend systems Work closely with teams across the company to deliver new features and solutions Contribute to the ongoing improvement of our backend platforms Location This position is based in Madrid.

neoris is looking for a Backend Software Engineer with a focus on .NET technologies to join the team in Madrid, Spain. This hybrid position involves both in-office and remote work. Role overview This role centers on designing, developing, and maintaining backend systems that support neoris applications. The work involves building reliable services and ensuring performance and scalability. Collaboration Work closely with colleagues from different disciplines to deliver software solutions that align with business objectives. Regular communication with cross-functional teams is part of the job. Location This is a hybrid role based in Madrid, Spain. Some days will be spent in the office, with flexibility for remote work.

Role Overview atexis is looking for a Senior Integrated Logistics Support Engineer in Madrid. This role focuses on improving logistics operations and delivering solutions that help clients achieve reliable, efficient service. What You Will Do Enhance and optimize logistics processes for client projects Support clients by identifying and implementing improvements in service delivery Apply integrated logistics support expertise to drive operational efficiency and reliability