Senior Backend Software Engineer

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

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.

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

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.

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.

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!

Are you ready to make a significant impact? At Cabify, we are on a mission to transform urban living by enhancing mobility for residents, seamlessly connecting riders with drivers at their fingertips. Our vision is to create cities where private cars are a thing of the past. Are you interested in being part of this transformative journey? At Cabify, our commitment to diversity shapes our Product & Engineering teams. We actively seek talent from a variety of backgrounds, supporting initiatives such as Women Tech Dating and our Internal Diversity Committee. Our inclusive job descriptions reflect our dedication to an environment where every contribution is valued. Join us to be a part of innovative teams that truly mirror the diverse talent in the tech sector. With over 20 million users globally, we operate in 8 countries and 90 cities, rapidly adapting our product to maintain leadership in various markets while prioritizing sustainability. The Role: We are seeking a skilled Backend Software Engineer with experience in any backend technology. Your day-to-day tasks will involve working with Go, Elixir, or Ruby. Even if your background is primarily in languages like Java, we believe you can quickly adapt and learn new languages. What matters most to us is your adaptability and ability to learn programming languages swiftly. At Cabify, you will: Collaborate with principal engineers on development planning and architectural design. Coordinate subprojects, building and maintaining robust, testable, and data-driven applications. Enhance the reliability, scalability, and performance of our services. Take ownership of your code all the way to production utilizing a self-service continuous delivery pipeline. Engage in host-level problem-solving and contribute to improving detection methods. Be a key player in fostering our engineering culture, prioritizing quality through peer reviews, monitoring, and best practices.

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.

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.

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).

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.

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.

Ebury empowers ambitious businesses to achieve global expansion, and we apply the same philosophy to our workforce. We promote innovation, collaboration, and problem-solving, creating an environment where every employee feels valued, supported, and empowered to thrive.If you are a team player eager to revolutionize global business operations, reach out to us. We would love to explore how Ebury can enhance your career and help you shape the future.Senior Software EngineerMadrid Office - Hybrid: 4 days in the office, 1 day working from homeThe FinCore Engineering team at Ebury is looking for a talented Software Engineer to play a vital role in our diverse team located across South America and Europe. The successful candidate will be responsible for developing and optimizing our multi-currency accounting system and facilitating foreign currency exchanges. Your contributions will be essential as we strive to elevate our platform and deliver the best FX experience for our clients and operational teams.As a Senior Software Engineer, your technical expertise will be crucial to our ongoing innovation and growth. We prioritize collaboration and commitment, functioning in a distributed model where effective teamwork is essential.

Ebury empowers ambitious businesses to achieve global growth, and we adopt the same philosophy for our team members. We promote innovation, collaboration, and problem-solving, creating an inclusive environment where everyone feels valued, supported, and empowered to thrive.If you are a collaborative individual eager to revolutionize how businesses operate on a global scale, we invite you to connect with us. Let's explore how Ebury can fast-track your career and enable you to shape the future.Senior Software Engineer (Money Flows)Ebury Madrid or Malaga Office - Hybrid: 4 days in the office, 1 day working from homeThe Engineering team at Ebury is searching for a Senior Software Engineer to play a pivotal role within our diverse team across South America and Europe. The successful candidate will be responsible for developing and optimizing our multi-currency account systems, as well as managing incoming funds and outgoing payment processes. Your contributions will be vital as we continually enhance our platform to deliver an unparalleled payment experience for our clients and operational teams.As a Senior Software Engineer, your technical expertise and skill set will be crucial to driving our innovation and growth. We value strong collaboration and commitment, working effectively within a distributed team.

At KingMakers, we are proud to be the leading platform for sports and iGaming entertainment in Africa, where millions of players engage daily across various markets. Since our inception with BetKing in Nigeria in 2018, we have rapidly expanded our footprint, most recently with the acquisition of SuperSportBet in South Africa. Our dynamic Product & Engineering organization boasts hubs across Europe and Africa, and we are committed to scaling our innovative technology platform in real-time.In this pivotal role, you will be at the forefront of our growth trajectory by driving our payments infrastructure. Every market expansion hinges on our payment systems, which handle every deposit, withdrawal, and transaction across all regions we serve. As we grow, you will face increasing complexities involving more markets, payment providers, and regulatory environments, alongside higher transaction volumes.This role is high-impact; your work will directly influence the financial infrastructure that supports our operations across multiple markets. Reliability, accuracy, and performance are paramount, and your engineering contributions will have immediate implications for both our players and the business. You will be an integral part of a collaborative squad, involved in the entire software development lifecycle, from design to production ownership.Key Responsibilities:Design, develop, and maintain payment processing services, integrating with third-party payment providers, PSPs, and financial networks.Manage features from inception to delivery, including technical design, testing, monitoring, and production support.Utilize event-driven architectures (Kafka, Service Bus) to facilitate reliable, asynchronous processing of high-volume financial transactions.Contribute to a microservices architecture built on .NET/C#, with REST APIs, gRPC, and Azure cloud infrastructure.Work closely with product managers, QA engineers, and other teams (Risk, Platform, Player Account) to create seamless user experiences.Participate in code reviews and contribute to the overall quality of engineering within the squad.Assist in diagnosing and resolving production incidents by identifying root causes.Engage in technical discussions to advocate for optimal solutions.

Join Ebury, a leading fintech company revolutionizing the financial services landscape. We are looking for a Senior Software Engineer to be a pivotal part of our innovative team in Madrid. In this role, you will leverage your expertise to develop and enhance our cutting-edge financial solutions, collaborating with cross-functional teams to deliver exceptional products.

Join aircall, a leading AI-driven customer communication platform, as we innovate the way businesses interact with their customers. With over 22,000 companies relying on our services, we integrate voice, SMS, WhatsApp, and AI into a unified workspace designed to enhance efficiency and drive revenue.Our vision is simple yet powerful: empower teams to work smarter, not harder. With tools like our AI Voice Agent for automating routine calls and AI Assist Pro for real-time guidance, we ensure that our teams can achieve peak performance and fast resolutions.Headquartered in Paris, with a strong presence in North America and multiple offices including Madrid, London, and New York City, aircall is backed by top-tier investors and is rapidly evolving through AI innovation across various product lines.At aircall, you will be part of a dynamic and ambitious team focused on impactful results. We prioritize ownership, continuous learning, and agile practices. If you thrive in a collaborative and fast-paced environment, you will flourish here.We are seeking a dedicated and enthusiastic Senior Software Engineer to enhance our engineering department and contribute to our innovative projects.In this role, you will oversee the design, development, deployment, and maintenance of essential features that deliver significant value to our customers. You will champion operational excellence and best practices while mentoring your team and the wider engineering community.Your work will focus on elevating quality, excellence, and agility within our delivery processes. You will work primarily with NodeJS and Typescript, ensuring our solutions are effectively hosted on AWS.

Join our innovative team as a Senior Software Engineer specializing in orchestration and automation at Celonis in Madrid. In this pivotal role, you will be instrumental in designing and developing cutting-edge software solutions that enhance our automation capabilities. Collaborate with cross-functional teams to streamline processes and drive efficiency across our platforms.

At Celonis, we are at the forefront of Process Intelligence technology, recognized globally as a leader among the fastest-growing SaaS companies. Our mission is to harness the power of AI, data, and intelligence to revolutionize business processes, and we're seeking talented individuals like you to help us achieve this vision. Are you ready to make an impact?The Team:Join our dynamic Celonis Support Services team, a vital component of our 3-Level Support model, as a dedicated 2nd Level Technical Support Engineer. Your base will be in Madrid, where you will report directly to the Director of Customer Support.The Role:As a Senior Software Support Engineer, you will be an essential player in diagnosing and resolving intricate technical and product-related challenges across the Celonis Product Suite. You will act as a vital link between our global customers, partners, and our internal Value Engineering & Delivery, Development, and Product Management teams. We are looking for someone who is enthusiastic about becoming a deep technical expert in Celonis infrastructure and software while contributing to a customer-centered SaaS environment.Your Responsibilities:Focus on expert technical analysis, resolution of complex incidents, and driving ongoing improvements in support operations:Deliver 2nd Level technical support for customer inquiries related to Celonis Systems & Products.Act as a Technical Contact for Premier Customers.Take ownership of complex cases by accepting, qualifying, driving, and resolving them in alignment with ITSM processes and KPI standards.Conduct in-depth analysis, diagnosis, and recovery of complex technical issues, frequently collaborating with customers and internal Product and Engineering teams.Engage in Root Cause Analysis (RCA) activities to enhance the team’s support Knowledge Base.Actively contribute to Continual Service Improvement (CSI) initiatives, including Knowledge Centred Service (KCS).Prepare and present Webcasts on selected technical topics for customers and internal support staff.Participate in an on-call schedule to ensure continuous global coverage.