Front End Developer (Madrid, Spain)

Location: Madrid, Madrid, Spain

Department: Tech Team

Type: Full Time

Min. Experience: Experienced

Front End Developer


We sit at the epicenter of innovation in the marketing and advertising world and have been spearheading mobile adtech/martech innovation since 2010. We are unique in that we take a mobile-centric approach when developing sophisticated data-driven branding strategies for large global brands. Since our founding, mobile has taken over digital while at the same time blurring the lines between the physical and digital worlds. For this purpose we developed, Sonata, our own proprietary mobile engagement platform through which we have achieved global scale serving clients in over 70 countries through our 9 offices in Europe and the Americas.  As we continue to grow our global footprint we hire only the best non-conforming experts in digital marketing and advertising.

Our Personality: We are ambitious, demanding and optimistic go getters. We are non-conformists, we are intrapreneurs, working hard together as a team to drive and achieve our ambitious growth plans. In short, we smell opportunity where others see vulnerability.

What we do:

Sonata’s technology platform supports a real-time bidding system that handles over 10 billion events every day (vs ~ 3 billion daily Google search queries), a reporting system that aggregates and analyzes terabytes of data in real-time, and a learning system that applies machine learning and business intelligence techniques to over 40 petabytes of data. These systems all work in harmony so that Sonata can serve the right advertisement to the right user at the right time. The Bidder and Data team sits at the core of our technology as the key decision-making agent for our systems. We research and develop the algorithms and models that make our software intelligent, as well as implementing, scaling, and maintaining the code that powers our production systems.

Some of the solutions we work on include:

Click/Conversion Prediction and Optimization: How do you use the rich data we have about users to make predictions? How do you handle rare conversion events, such as purchases, walk ins, etc.? How do you deal with cold start problems?

Bidding Strategies: How do you translate a click or conversion score into a bid? What if it’s a first price auction, second price auction, or has a floor? How do you take into account pacing for hour of day, day of week, and special holidays like Thanksgiving and Christmas?

A/B Testing: When is a result significant? How do you weight across many different campaigns?

Fraud Detection: Many users of the web are not human, but rather bots, crawlers, or other pieces of software that are loading web pages. How do you detect these “users” and prevent Sonata from showing ads to them?

Recommended Systems and Audience Profiling: Sonata dynamically tailors ads to each user, including the products shown. How do you decide which products to show in just a few milliseconds? How do you build quality audiences based on several data dimensions (location, navigation history and campaign events)?

We work with some of the most cutting-edge technologies to solve these problems, including Hadoop, Spark, Flume and Hive. We program mostly in Java, Js & Node.js and Python.

We are currently looking for a Front-End Developer for our Sonata Team. Main part of the work is dedicated to the frontend development, but back-end experience would be highly appreciated. Our frontend stack is based on MVC Backbone library and we are starting to build UI components using React library. Our backend stack is mostly powered by Node.js using Express as web server. We make heavy use of Mongodb but also use Redis and other database systems.

About you: You are an experienced engineer with at least 3 years’ experience developing Javascript UI views using a MVC library or UI Components like React. You may have also experience with the backend, especially with NodeJS and Express, and you're not afraid of jumping onto it when needed. You’re proficient in both English and Spanish and have excellent communication skills. As a teammate you are a person that peers look up to with respect for your technical prowess. You have worked in a startup environment and understand orderly chaos even though agile methodology is embedded in you.

Job description & responsibilities:

● Developing new UI functionality that will be used by users all around the world.

● Developing systems that will interact in real-time with millions of users daily.

● End-to-end responsibility from technical design to deployment and testing.

● Working hand-in-hand with an awesome team of developers and its Product Owner.

● Working closely with other teams: product, operations, marketing...

Requirements of the role:

● +3 years of experience in the same role.

● Frontend development specialist experienced in Backbone, React or Angular libraries.

● Knowledge of scss, grunt, bower, webpack...

● Expert in Javascript.

● Knowledge in object-oriented programming languages (Typescript, JAVA, ...).

● Experience with REST APIs specification.

● Experience with WebSockets.

● NoSQL databases knowledge (MongoDB and Redis desirable).

● Experience with Agile development practices (Scrum, JIRA).

● English language, full professional proficiency.

Bonus points:

● Experience with Javascript ES6 standard.

● Backend development knowledge with NodeJS and Express.

● Experience with Typescript.

● Experience with Amazon Web Services use.

● Shipping fast. Not being afraid to try and fail.

● Ability to work independently, set timelines and execute to plan.

● Verbal and written communication skills.

● Consider unit testing is a must, quality assurance is a priority.

● Interest in learning and sharing knowledge with the other team members.

● Backend experience.

● Learning quickly and being self-reliant. Experience in working in a startup or small teams



● Permanent position based in Madrid.

● Strong possibilities of internal promotion in an international firm.

● Very Competitive compensation package, according with the candidate´s profile &


● Ticket Restaurant / Health Insurance.

● Company sponsored training.

● Great working environment.

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