Web Developer (Intern)

Web Developer Intern

Location: Madrid Spain Onsite

Team: Publisher Success

Position Type: Internship

Refinery89 is a Dutch AdTech company headquartered in Madrid working with premium publishers around the world to optimize their programmatic advertising performance.

Through advanced technology data and hands on technical support we help publishers increase advertising revenue improve efficiency and gain greater transparency across their monetization stack.

Our international team operates at the intersection of technology digital advertising data and publisher operations.

We are looking for a Web Developer Intern to join our Publisher Success team in Madrid.

This internship is designed for a student recent graduate or early career candidate who already has a foundation in HTML CSS and JavaScript and wants to gain practical professional experience working with websites technical troubleshooting data and advertising technology.

You do not need previous AdTech experience. We will train you on the AdTech side from zero.

During the internship you will work with real publisher websites browser developer tools HTML CSS JavaScript advertising technologies reporting platforms and technical diagnostics while receiving support and guidance from experienced members of the team.

The internship is ideal for someone who wants to strengthen their web development fundamentals while gaining experience in technical troubleshooting website integrations data publisher support and Technical Account Management.

Website Troubleshooting

Support the investigation of technical issues affecting publisher websites.

Use browser developer tools to inspect HTML CSS JavaScript scripts network activity and browser errors.

Help identify issues related to page structure styling scripts advertising tags or website configuration.

Reproduce technical problems and investigate their likely cause.

Review browser console errors and network requests when diagnosing issues.

Gather the technical information needed before escalating more complex problems to senior team members.

Web Technologies and Integrations

Work with HTML CSS and JavaScript across real publisher websites.

Help investigate how scripts and third party technologies interact with webpages.

Support the implementation and validation of advertising related website integrations.

Review website configurations and identify potential technical issues.

Learn how APIs scripts browser requests and advertising technologies interact within modern websites.

Publisher Monitoring

Support the monitoring of publisher websites and identify unusual behavior.

Perform regular technical health checks.

Help spot problems affecting advertising performance or website functionality.

Investigate whether changes on a website may be affecting advertising delivery.

Learn how different components of a publisher website interact with advertising technology.

Data and Performance

Learn to interpret advertising metrics such as CPM RPM fill rate impressions and revenue.

Identify unusual changes in performance.

Support investigations into whether an issue may be technical commercial or related to traffic.

Use data to support technical investigations.

Work with spreadsheets and internal reporting tools.

Technical Communication

Create clear technical handoffs including screenshots URLs browser information and descriptions of the issue.

Learn to explain technical findings in simple and understandable language.

Support communication with publishers in English about technical issues and their resolution.

Collaborate with Technical Account Managers developers advertising specialists and other internal teams.

You will receive structured onboarding and gradually develop knowledge in areas including:

Advanced website troubleshooting.

HTML CSS and JavaScript in production environments.

Browser developer tools.

JavaScript troubleshooting.

Network requests and browser debugging.

APIs and web technologies.

Website integrations.

Google Ad Manager.

Prebid.

SSPs.

Programmatic advertising.

Advertising tags and website integrations.

Publisher monetization.

Reporting and performance analysis.

Technical Account Management.

You are not expected to know AdTech before joining.

Fluent professional English (C1/C2).

Practical knowledge of HTML CSS and JavaScript.

Basic understanding of how websites are structured and how front end technologies interact.

Some experience using browser developer tools to inspect websites troubleshoot issues or understand page behavior.

Strong technical curiosity.

Strong problem solving skills.

Comfort investigating unfamiliar technical problems.

Clear written and verbal communication.

Basic numeracy and confidence working with percentages and data.

Reliability and attention to detail.

A genuine eagerness to learn.

The confidence to say I dont know yet but I can investigate.

Professional experience is not required.

Your experience can come from university projects bootcamps internships freelance work personal websites GitHub projects or technical side projects.

We are particularly interested in students recent graduates or early career candidates from areas such as:

Computer Science.

Software Engineering.

Web Development.

Programming.

Information Technology.

Telecommunications.

Data.

Engineering.

A formal technical degree is preferred but not required if you can demonstrate practical technical experience.

To participate in this internship you must be legally eligible to complete an internship in Spain.

Candidates should be enrolled in an educational program or otherwise be eligible to complete an internship agreement through a university educational institution or training provider.

Please confirm your internship eligibility when applying.

Experience building or maintaining websites.

Experience troubleshooting JavaScript errors.

Familiarity with the browser console.

Familiarity with network requests.

Experience working with APIs.

Basic understanding of HTTP requests responses and browser behavior.

Exposure to databases.

Git or GitHub experience.

Personal web development projects.

Experience with third party scripts or website integrations.

Experience helping users solve technical issues.

Basic spreadsheet skills.

Spanish language skills are considered a plus but are not required.

Dutch language skills are considered a plus but are not required.

This internship could be a strong fit if:

You enjoy building inspecting and understanding websites.

Something on a website stops working and your instinct is to investigate why.

You are comfortable opening browser developer tools and inspecting what is happening behind a page.

You have worked with HTML CSS and JavaScript through your studies personal projects or previous experience and want to apply that knowledge in a real business environment.

You see an error in the browser console and want to understand what caused it.

You enjoy solving technical problems even when you do not immediately know the answer.

You like working with both technology and people.

You want to gain professional experience with web technologies without necessarily following a traditional software engineering path.

Although the position is called Web Developer Intern this is not a traditional software development internship.

You will not spend your internship primarily building applications developing product features or working as part of a software engineering product team.

The internship focuses mainly on web technologies website troubleshooting technical investigation integrations publisher support advertising technology performance monitoring and Technical Account Management.

You will regularly use HTML CSS JavaScript browser developer tools APIs and other web technologies to investigate and understand technical issues.

This role is therefore particularly suitable for someone with a web development background who enjoys understanding how websites work debugging problems working with integrations and applying technical knowledge in a client facing business environment.

Our interview process consists of three stages.

1. Initial Screening

A short introductory conversation with our recruitment team to understand your background motivation English level internship eligibility and web development experience.

2. Team Interview

A conversation with the Hiring Manager or Technical Account Management team focused on your technical curiosity web knowledge problem solving approach and how you invest...