Senior Software Engineer - Runtime Sensor

Cast AI; Madrid; A distancia; EUR 90.000 - 110.000; Jornada completa

Descripción de la vacante

A leading application performance platform in Madrid is looking for a Senior Software Engineer to develop their Kubernetes security product. You will work with a skilled team to design scalable software, write maintainable code, and ensure software reliability. This role offers a highly technical environment, minimal bureaucracy, and a monthly salary up to 9000 € based on experience.

Servicios

Highly skilled team

Flexible working location

10% time for personal projects

Minimal meetings/bureaucracy

Formación

• Physically present in GMT 0 to GMT +3.
• Strong software engineering skills required.
• Experience with Linux Containers is essential.
• Analytical and problem-solving skills needed.
• Strong verbal and written communication skills are important.

Responsabilidades

• Collaborate on product ideas and requirements.
• Design and architect scalable software.
• Write clean and maintainable code.
• Ensure software reliability with test coverage.
• Respond to incidents and customer issues.

Conocimientos

Software engineering skills

Experience with Linux Containers

Distributed systems knowledge

Analytical problem-solving

Strong communication skills

Herramientas

Go

eBPF

ClickHouse

PostgreSQL

GCP Pub/Sub

gRPC

REST APIs

Kubernetes

GitLab CI

ArgoCD

Prometheus

Grafana

Loki

Tempo

Descripción del empleo

Why Cast AI?

Cast AI is the leading Application Performance Automation (APA) platform, enabling customers to cut cloud costs, improve performance, and boost productivity – automatically.

Built originally for Kubernetes, Cast AI goes beyond cost and observability by delivering real-time, autonomous optimization across any cloud environment. The platform continuously analyzes workloads, rightsizes resources, and rebalances clusters without manual intervention, ensuring applications run faster, more reliably, and more efficiently.

Headquartered in Miami, Florida, Cast AI has employees in more than 32 countries worldwide and supports some of the world’s most innovative teams running their applications on all major cloud, hybrid, and on-premises environments. Over 2,100 companies already rely on Cast - from BMW and Akamai to Hugging Face and NielsenIQ.

What’s next? Backed by our $108M Series C, we’re doubling down on making APA the new standard for DevOps and MLOps, and everything in between.

Core values that hold us all together

PRACTICE CUSTOMER OBSESSION. Focus on the customer journey and work backwards. Strive to deliver customer value and continuously solve customer problems. Listen to customer feedback, act, and iterate to improve customer experience.

LEAD. Take ownership and lead through action. Think and act on behalf of the entire company to build long-term value across team boundaries.

DEVELOP AND HIRE THE BEST. Strive to raise the performance bar by continuously investing in yourself, the team, and by hiring the best possible candidates for every position. Drive towards personal development and professional growth, and mentor others to raise the collective bar.

EXPECT AND ADVOCATE CHANGE. Strive to innovate and accept the inevitable change that comes with innovation. Constantly welcome new ideas and opinions. Share insights responsibly with unwavering openness, honesty, and respect. Once a path is chosen, be ready to disagree and commit to a direction.

What does the Runtime Security Team do?

The goal of the Runtime Security Team is to develop part of a Kubernetes Security Posture Management (KSPM) product that acts as a last line of defense for our customers, detecting any malicious activity going on in our customers' Kubernetes clusters, notifying the customer, and also blocking this activity.

While most other parts of the Cast AI KSPM product look for potential threats based on current configuration, runtime security analyzes what is actually happening in the cluster to surface malicious activity. For example, runtime security detects these indicators of compromise :

• Crypto miners or known hacking tools being executed
• Container drift
• Unexpected writes to sensitive files such as /etc/passwd.

The Runtime Security Team is responsible for their part of the product end-to-end, including developing an agent that audits Kubernetes workloads using eBPF on the Linux kernel layer, designing and implementing new detections for malicious activity, collecting and processing vast amounts of data from the customers' clusters to enable these detections, and surfacing the most valuable insights from all of this collected data.

Role overview: We’re looking for a

• Senior Software Engineer
• to help build the runtime component behind our Kubernetes Security product. You’ll work deep in the guts of Linux, tracing live application execution using eBPF, and turning low-level signals into high-impact insights and threat detections by building a high-scale backend in Go that runs on Kubernetes and ingests millions of events collected from this tracing. In this role, you will own the full pipeline: from the eBPF-based agent that monitors runtime behavior, to the backend systems that process and aggregate data at scale, to the detection logic that flags malicious activity. The team is solving tough problems: figuring out how to reliably trace key aspects of application behavior through the Linux kernel in ways that are hard to evade, processing massive event volumes on the order of millions of events per second, without missing anything (a missed event could mean a missed detection), and carefully balancing what’s done in the agent vs. the backend to optimize performance, cost, detection accuracy, and flexibility.

Responsibilities :

As a Senior Software Engineer, you will work in a highly skilled team and collaborate throughout the full development lifecycle.

• Participate in creating ideas for the product, gathering requirements, and solving customer needs.
• Design and architect software, leveraging your experience to ensure scalability, maintainability, and performance.
• Write clean, maintainable, and documented code using best practices and coding standards.
• Ensure software reliability through test coverage and local testing.
• Respond to incidents to resolve customer issues or service disruptions.

Here are some of the tools we use daily :

• Go (main language)
• eBPF
• ClickHouse
• PostgreSQL
• GCP Pub/Sub
• gRPC
• REST APIs
• Kubernetes
• Azure
• GitLab CI
• ArgoCD
• Prometheus
• Grafana
• Loki
• Tempo

Note: Not every candidate knows every tool — our stack evolves, and we care more about your ability to learn.

Requirements :

• You have to be physically in any of the European countries GMT 0 to GMT +3
• Strong software engineering skills
• Strong experience with Linux Containers
• Experience with distributed systems
• CI and git knowledge
• Strong analytical, problem-solving, and troubleshooting skills
• Strong verbal and written communication skills
• Ability to work independently or with a group
• A “yes we can” attitude.

What's in it for you?

• Team of highly skilled professionals to work with and learn from
• Very technically challenging domain with unique problems
• Time to focus on work with a minimum overhead of meetings, bureaucracy, etc.
• Flexible working location
• 10% time to focus on self-improvement or personal pet projects
• Monthly salary up to 9000 € depending on the level of experience.