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.

About the Role resilientco is looking for a Senior PHP Backend Engineer based in Spain. This role focuses on building and maintaining backend systems that support core applications. The work centers on PHP and requires experience designing reliable solutions for modern software products.

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!

Abacum is looking for a Senior Backend Engineer focused on integrations. This position is fully remote within Spain. Role overview This role centers on designing and building backend solutions that connect Abacum's product with a range of external systems. The work involves improving integration features while maintaining strong performance and scalability. What you will do Create and maintain backend services that enable seamless integration with third-party platforms. Enhance existing product capabilities by developing new integration features. Ensure backend systems operate efficiently and scale to meet business needs. Requirements Experience building backend solutions, with a focus on integrations. Strong understanding of system performance and scalability. Ability to work independently in a remote setting within Spain.

Join us at Fever, the premier tech platform dedicated to enhancing cultural and live entertainment experiences globally.Our mission is to democratize access to culture and entertainment. Utilizing our advanced technology and data-driven strategies, we are changing how audiences engage with live events. Every month, over 300 million individuals across more than 40 countries discover unforgettable experiences on our platform, while we empower event creators to innovate and grow their reach.We proudly collaborate with industry giants such as Netflix, F.C. Barcelona, and Primavera Sound, delivering internationally acclaimed experiences and backed by leading global investors. Impressive, isn’t it?To further our mission, we seek exceptional talent with a proactive mindset, eager to contribute to the future of entertainment. Are you ready to be part of this journey?The engineering team is the backbone of our user-friendly iOS and Android applications and website, responsible for developing, enhancing, and maintaining all Fever services, ensuring that users have outstanding experiences.About the RolePosition: Senior Software Engineer (Backend Platform)Location: SpainWe are looking for a highly skilled software developer with a proven track record of delivering exceptional results. A person who values code quality and emphasizes doing things correctly, not just completing tasks.Collaborate within an agile, cross-functional team alongside other talented software engineers and product designers.Develop production-quality code and implement solutions capable of handling significant traffic.Mentor team members through code reviews, architecture design sessions, and pair programming.Receive mentorship from colleagues in areas where you seek to grow.During your onboarding period, you will:Engage in a structured program designed to facilitate a smooth transition into your role.

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

As a Senior Backend Software Engineer at Blacklane, you will join one of our autonomous agile teams. Your contributions will enhance the services that drive our innovative platform, improve our back-office systems, and address integration challenges that enable our business partners to seamlessly connect with Blacklane.Our tech stack comprises Ruby, Go, TypeScript, and Java services, designed through Domain-Driven Design (DDD). These services are deployed within our Kubernetes cluster and communicate via domain events using SQS and Kafka. We utilize a variety of data storage technologies, including PostgreSQL, MySQL, Elasticsearch, Redis, and DynamoDB. For infrastructure and cloud resources, we primarily leverage AWS, managing provisioning through Terraform.

ANYbotics is an innovative and rapidly expanding technology company committed to revolutionizing the field of mobile robotics across diverse sectors. We invite you to join our dynamic and talented team of over 200 professionals, working on pioneering robotic technologies.The OpportunityWe are searching for a Senior Backend Engineer to become a vital member of our agile software engineering team. In this role, you will be responsible for architecting and developing the backend for the next generation of robotic applications for our flagship product, ANYmal. Collaborating closely with your teammates and leading robotics engineers, you will design and implement sophisticated software solutions that empower ANYmal to undertake increasingly complex tasks.The APIs developed by your team will lay the groundwork for strategic partnerships with software and cloud technology providers, facilitating seamless integration into our clients' facility management systems and enabling the creation of comprehensive robotic inspection solutions.At ANYbotics, we continually innovate to enhance the performance and capabilities of our robots, helping clients derive valuable insights from their facilities and processes with efficiency and ease. Leverage your technical expertise in web technologies to contribute to making our robots smarter, more reliable, and user-friendly.The Market & Our TechnologyANYbotics is at the forefront of transforming the industrial landscape by integrating robotics into a wide array of groundbreaking applications that were previously unattainable (refer to our case studies in sectors such as Chemicals, Oil & Gas, Railways, Wind Energy, Mining, and Construction). Our clientele consists of major asset operators and service providers in the industrial sector, pioneering the use of robotic technology for inspection and maintenance tasks. Our solutions facilitate autonomous routine inspections and monitoring of extensive industrial facilities, enhancing safety and productivity. We engineer a variety of customized hardware systems, including the complete robotic platform, actuators, sensors, inspection payloads, charging systems, and software, achieving exceptional mobility, autonomy, and inspection capabilities, often powered by AI. Our technology has been validated through long-term pilot projects, and we are now scaling our solutions for commercialization, deploying them directly in operations at client facilities across the globe.About UsANYbotics is a pioneering robotics firm specializing in advanced autonomous systems. Following a successful Series B funding round, we are poised for significant growth...

About the Project:Yei Finance is a pioneering decentralized, non-custodial money market protocol built on the Sei network, dedicated to delivering innovative and versatile financial solutions. Users can benefit from competitive yields, borrow via over-collateralized or flash loans, and manage risks using advanced tools—all while harnessing Sei’s remarkable speed and low costs.Our flagship product, Clovis, achieved over $400M in Total Value Locked (TVL) at its peak, generated $5.5M in protocol revenue over the past year, and has established itself as the largest protocol on Sei. Furthermore, we launched the first lending-boosted decentralized exchange (DEX) on Sei, where YeiSwap compounds YeiLend yields to drive over $230M in monthly trading volume and $147M in bridge flow. Clovis is set to expand this successful model by becoming multichain, positioning itself as the cross-chain prime brokerage layer for decentralized finance (DeFi).Who We Are:A dedicated team of builders from esteemed Web3 organizations, including AAVE, Wormhole, Venus Labs, OKX, among others.Supported by leading investors such as Outlier Ventures, Manifold, DWF Ventures, and the Sei Foundation.Collaborating with industry giants like Circle, OKX Wallet, Binance Wallet, Frax, Stargate, and more.The Opportunity:We are on the lookout for a highly skilled Senior Engineer to become part of our core development team and take charge of the design and implementation of our next-generation cross-chain lending protocol. This role will emphasize smart contract security and architecture, as well as the development of essential off-chain services that guarantee the protocol’s efficiency and strength.What You’ll Do:Design, develop, and refine DeFi protocols on EVM-compatible chains, prioritizing contract architecture, security, gas optimization, and upgradability.Create crucial backend and off-chain services using Go or Python, including monitoring systems, liquidation bots, and liquidity rebalancers.Address cross-chain integration challenges, ensuring atomicity, data consistency, and reliable asset bridging in an asynchronous environment.Rapidly iterate in an Agile environment and produce comprehensive documentation and system architecture diagrams.Who You Are:Startup-oriented: Thrives in a dynamic, fast-paced environment.

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.

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 constructor-1 is hiring a Senior Backend Engineer focused on Attribute Enrichment. This position is fully remote within Spain. The role centers on improving backend systems, strengthening data accuracy, and enriching user attributes to support a smooth experience for clients. What You Will Do Enhance and maintain backend systems with a focus on attribute enrichment Work closely with cross-functional teams to develop solutions that improve data quality Help ensure user attributes are accurate and comprehensive for downstream services What We Look For Professional experience with backend technologies Strong problem-solving skills and interest in complex technical challenges Ability to collaborate effectively with colleagues across different functions Location Remote within Spain.

Join Our TeamAt Quadrivia, we are revolutionizing healthcare technology with Qu, a fully controllable and customizable AI assistant crafted by clinicians for clinicians. We tackle the pressing shortage of healthcare professionals by providing timely, personal, and dependable support for a variety of clinical tasks throughout the care continuum. Qu is tailored for healthcare providers, payers, and pharmaceutical companies, ensuring easy customization and seamless integration into existing workflows for optimal assistance across the care spectrum.Your ImpactAs a Senior Backend Software Engineer, you will architect and develop the robust backend systems that power the Quadrivia clinical AI platform. This includes building high-availability services, creating event-driven architectures, developing data pipelines, and establishing orchestration layers for our clinical AI agents.This position is highly technical and hands-on, playing a critical role in ensuring our systems' reliability, safety, and performance.

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.

Welcome to Fever!We are Fever, the premier technology platform dedicated to culture and live entertainment.Our goal? To make culture and entertainment accessible to everyone. Leveraging our innovative technology and data-driven strategies, we are transforming the way audiences engage with live events. Each month, our platform encourages over 300 million individuals across more than 40 countries to explore unforgettable experiences while equipping event creators with the tools to expand, innovate, and elevate their offerings.Our achievements? Collaborations with industry giants like Netflix, F.C. Barcelona, and Primavera Sound, the presentation of internationally recognized experiences, and backing from several prominent global investors! Impressive, right?To realize our vision, we seek talented individuals with a proactive approach who are keen to shape the future of entertainment!Are you ready to join us on this journey?Now, let’s dive into the specifics of this role and how you will contribute to Fever’s mission.

Role overview Deel seeks a Senior Backend Engineer with strong experience in Node.js and AWS. The focus is on building and enhancing backend systems that power Deel’s products and services within Spain. What you will do Design and implement backend solutions using Node.js and AWS services Improve and fine-tune existing systems to boost performance and reliability Integrate backend services with various internal and external platforms Work closely with engineers and other team members to reinforce cloud infrastructure Deliver software that aligns with client needs and quality expectations Location This role is based in Spain.

About UsConstructor is a pioneering platform revolutionizing search and discovery in the ecommerce sector. We are dedicated to optimizing critical metrics such as revenue, conversion rates, and profit margins. Our search engine is entirely developed in-house, utilizing advanced transformer models and generative large language models (LLMs). This foundational technology empowers various applications, from search functionalities to personalized recommendations and interactive shopping agents. Engineering is our largest department, and we are proud to affirm that our proprietary engine has consistently outperformed competitors in A/B testing, a testament to our commitment to excellence. We are at the forefront of AI innovation, constantly pushing boundaries to maintain our edge in the market.Our engine is designed for extreme scalability, processing over 1 billion queries daily across 150 languages and approximately 100 countries. Our technology supports some of the world's leading ecommerce brands, including Sephora, Under Armour, and Petco.At Constructor, we are a passionate team eager to solve complex challenges and enhance the experiences of our customers and colleagues alike. We prioritize values such as empathy, openness, curiosity, and a commitment to continuous improvement. We believe that empowering everyone within the organization to excel in their roles leads to remarkable outcomes.Founded in 2019 by Eli Finkelshteyn and Dan McCormick, Constructor is a U.S.-based company that continues to thrive under their leadership.About the TeamThe Recommendations team is pivotal in enhancing user experiences for our customers and their end-users. We comprise a dedicated group of cross-functional engineers who thrive on challenges and are committed to improving lives through technology. We uphold values of transparency, curiosity, and continuous refinement in our work, believing that empowering team members to take initiative fosters exceptional results.Our team is focused on advancing traditional product discovery methods while exploring innovative solutions powered by large language models, pioneering a new era of user engagement and innovation.The Recommendations team manages multiple service endpoints and develops our own cloud-deployed solutions using Python, which necessitates leveraging NoSQL databases and interfacing with both internal and external services. Our future roadmap includes transitioning all major developments into high-load distributed services.About the JobThis role primarily involves designing, delivering, and maintaining high-load real-time web services in close collaboration with talented engineers from both the recommendations team and other departments.Develop, deploy, and support robust recommendation services, including I/O-bound web services, CPU-bound services, and data services.Create AWS CloudFormation scripts, Jenkins jobs, and GitHub actions adhering to industry best practices.Establish service observability, monitoring metrics, and alerting mechanisms (using tools like Prometheus and Grafana).

Join Exoticca as a Senior Backend Software Engineer!About UsExoticca is a trailblazing online travel agency dedicated to transforming the way people experience long-distance travel. Our mission revolves around crafting memorable life experiences through exceptional travel adventures. We pride ourselves on offering unmatched value, exploring diverse destinations, and creating extraordinary travel journeys while prioritizing our customers and the environment.Our vibrant, multicultural team is expanding rapidly, and we are on the lookout for passionate individuals who can contribute to building a pioneering travel company that redefines the industry.Your RoleWe are seeking a Senior Backend Software Engineer who excels at problem-solving. You will leverage engineering as a powerful tool to address real-world customer and business challenges.This position falls within our Trip Management System domain, where you will empower our travel specialists to design remarkable journeys at scale. You will contribute to the systems that convert destinations, itineraries, flights, hotels, and pricing strategies into structured, market-ready travel products. Through seamless product configuration, accuracy, and scalability, your work will directly enhance revenue, operational excellence, and customer satisfaction.While technology choices are important, the impact of your work is paramount. You will engage with PHP, Node.js, and contemporary AI tools, selecting the optimal approach for each unique challenge without being limited to a single technology stack.Why Join Us?Engage with genuine, impactful challenges that enhance customer experiences.Enjoy the freedom to select the right tools, including advanced AI technologies.Work within a team that values initiative, ownership, and meaningful contributions over titles and bureaucracy.Face scale-up challenges with opportunities to influence architecture, products, and workflows.If you seek stimulating problems, autonomy, and opportunities for professional growth, we welcome you!

Role overview Jobgether seeks a Senior Backend Engineer to advance our B2B product development efforts in Spain. The focus is on building and maintaining backend systems that support solutions for business clients. What you will do Design, build, and maintain scalable backend systems tailored for B2B applications Collaborate with cross-functional teams to deliver secure and reliable APIs Take part in technical decisions aimed at improving system performance and stability Requirements Significant experience in backend development Deep understanding of API design, security, and scalability Ability to work collaboratively with colleagues from different disciplines Contract details This is a B2B contract role based in Spain.