Web Dev Intern: HTML/CSS/JS & AdTech

Refinery89; Madrid; On-site; EUR 7,800 - 10,000; Full time

Job summary

Refinery89 is seeking a Web Developer Intern to join the Publisher Success team in Madrid. You will gain hands-on experience with HTML, CSS, and JavaScript while supporting real publisher websites, debugging issues, and learning ad tech integrations.

The role is ideal for students or recent graduates looking to strengthen their web development fundamentals, understand browser tooling, and collaborate with Technical Account Management and developers on practical projects.

Qualifications

• Fluent English required (C1/C2).
• Foundational knowledge of HTML, CSS and JavaScript.
• Understanding of how websites are structured and how frontend technologies interact.
• Experience using browser developer tools to inspect pages or troubleshoot issues.

Responsibilities

• Troubleshoot publisher websites and investigate technical issues using browser tools.
• Work with HTML, CSS and JavaScript on real publisher sites.
• Help monitor websites and identify unusual behavior affecting ads.
• Learn how APIs and ad tech integrations interact with websites.
• Communicate technical findings clearly to publishers in English.

Skills

English (C1/C2)

HTML

CSS

JavaScript

Browser dev tools

Technical curiosity

Problem solving

Communication

Numeracy & data

Reliability

Tools

Git

Job description

Refinery89 is seeking a Web Developer Intern to join the Publisher Success team in Madrid. You will gain hands-on experience with HTML, CSS, and JavaScript while supporting real publisher websites, debugging issues, and learning ad tech integrations.

The role is ideal for students or recent graduates looking to strengthen their web development fundamentals, understand browser tooling, and collaborate with Technical Account Management and developers on practical projects.