As a Senior Software Development Engineer in Test (SDET), you will build the systems, infrastructure, and tooling that enable a high-scale technology platform to test applications under conditions that closely replicate the real world.

This is an engineering role, not a traditional manual QA position. You will write production-quality code and build testing platforms capable of validating performance, reliability, and scalability across applications serving millions of users globally. A key challenge will be creating environments and systems that can simulate traffic and workloads that are difficult to reproduce through conventional testing environments.

You will work closely with platform engineers and the broader engineering organization to give the team confidence that new code and infrastructure will perform reliably when deployed at scale.

This role is adecuado for an engineer who enjoys solving complex infrastructure, performance, and reliability problems and is comfortable independently designing solutions from the ground up.

Responsibilities

Design and build scalable testing systems, platforms, and infrastructure that replicate real-world production conditions

Develop software and tooling to test application performance, reliability, scalability, and infrastructure behavior at high traffic volumes

Build and maintain load, performance, stress, and synthetic testing capabilities for applications serving millions of users globally

Create testing environments and processes that provide confidence that new code and infrastructure will scale successfully in production

Write high-quality code using TypeScript, Python, or similar languages to build testing tools, automation, and supporting systems

Design tests that identify performance bottlenecks related to latency, bandwidth, application speed, infrastructure capacity, and resource utilization





Integrate automated testing and quality validation into CI/CD pipelines and engineering workflows

Work with cloud-hosted applications and infrastructure across platforms such as AWS, Cloudflare, Google Cloud, or similar providers

Use Infrastructure as Code tools such as Terraform, Pulumi, or equivalent technologies to support repeatable and scalable testing environments

Partner closely with platform engineers to understand system architecture, production behavior, and infrastructure constraints

Analyze test results and production-like workloads to identify scalability risks before changes reach real-world traffic

Help establish the technical standards, systems, and processes for a new engineering-focused testing function

Requirements

Strong professional software engineering experience with the ability to independently design, build, and maintain software systems

Strong coding skills in TypeScript, Python, or comparable modern programming languages

Experience building automated testing systems, engineering tooling, testing infrastructure, or similar software-driven quality solutions

Hands-on experience with load testing, performance testing, stress testing, synthetic testing, or large-scale application validation

Experience working with applications or platforms serving millions of users or visitors, ideally at multi-million or tens-of-millions scale

Experience working with cloud-hosted applications and infrastructure using AWS, Google Cloud, Cloudflare,



or comparable platforms

Strong understanding of DevOps, platform engineering, infrastructure, scalability, and modern software deployment practices

Experience with CI/CD and integrating automated validation into continuous integration and deployment workflows

Experience with Infrastructure as Code using Terraform, Pulumi, or similar technologies

Strong understanding of application performance concepts including latency, bandwidth, throughput, scalability, reliability, and infrastructure optimization

Ability to independently investigate complex technical problems and build solutions with limited oversight

Strong written and spoken English with the ability to communicate technical decisions and collaborate effectively with a distributed engineering team

Preferred

Experience supporting globally distributed applications serving tens of millions of monthly visitors

Experience with high-traffic e-commerce platforms or other large-scale consumer-facing applications

Experience working with custom or internally built platforms rather than primarily testing third‑party or off‑the‑shelf software

Experience optimizing applications or infrastructure where speed, latency, bandwidth, and infrastructure cost are critical considerations

Experience building testing infrastructure or frameworks from the ground up rather than primarily working within established QA systems

Background in DevOps, Site Reliability Engineering, Platform Engineering, performance engineering, or infrastructure engineering

Experience working in fast-moving startup or lean engineering environments where engineers have significant ownership and autonomy

Benefits

Salary: $6,000 - $7500 USD per month

PTO: 15 days

Holidays: Local or US holidays

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📌 Senior Software Development Engineer in Test (Madrid)
🏢 Sur Global
📍 Madrid