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Working Student – Backend Developer & Data Detective

  • Hamburg
  • adjoe
  • Advertising Solutions
  • Working Student
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adjoe builds the technologies behind mobile apps growth and monetization. With our core product Playtime Arcade, we’ve become the global leader in rewarded advertising, an ad unit built on a simple premise: users earn real in-app rewards for engaging with new apps. The result is one of the most effective value exchanges in adtech, connecting advertisers and publishers with over 770 million users annually.

Running the Engine Behind 200M+ Daily Ad Decisions 

Behind every ad decision at adjoe is a system designed to operate at massive scale, serving more than 770 million mobile users every year. The Demand API Integrations team owns the systems that connect our platform to the global adtech ecosystem, handling over 5.5 billion API requests daily across installs, events, views, clicks, and postbacks from Mobile Measurement Partners.

We operate a dedicated A/B testing environment against live traffic to validate system behavior under real-world conditions, allowing us to evaluate advertiser integrations, benchmark partner performance, and verify attribution accuracy end-to-end before deploying globally.

We integrate TensorFlow-based ML models to predict user engagement and purchase likelihood, directly influencing real-time ad distribution. To meet our strict 100ms latency constraint, we prioritize efficient model serving, low-latency data access, and deliberate system design. 

Your Mission & Who We Are Looking For:
  • Backend foundation with a data mindset. You’re currently studying Computer Science, Data Science, or a related field, with hands-on experience in at least one backend language — Node.js, C#, or Java — and a genuine interest in picking up Go. You have strong SQL skills covering joins, aggregations, and query optimization, and you’re comfortable with relational databases like PostgreSQL or MySQL.
  • You have projects to show, not just coursework to list. You have a track record of past projects you can walk through and discuss — what you built, why, and what you’d do differently. At adjoe, you’ll be contributing to real backend services and data pipelines from day one, not writing throwaway code.
  • Comfortable in a modern engineering stack. You understand REST APIs, Git, and CI/CD pipelines, and have some familiarity with cloud platforms like AWS, GCP, or Azure. You’ll be working alongside experienced engineers who review your code and expect you to grow from that feedback.
  • Analytical and detail-oriented. You enjoy data-driven problem solving as much as writing code — helping improve data quality, validation, and monitoring processes, and collaborating with BI and data teams to deliver insights that matter.
    • What’s in It for You?

    At adjoe, you’re not here to just close JIRA tickets, you’re helping build the infrastructure behind one of the most impactful platforms in adtech. The systems you work on will reach hundreds of millions of users and power billions of decisions every day.

  • Go Big. Own projects with impact on 770M users and push adtech boundaries.

  • Move Fast. Ship solutions multiple times a day, learn from results, and keep momentum.

  • Be Direct. Solve problems openly and collaborate across teams.

  • Thrive Together. Grow with a diverse, global team of people from over 40 different countries that learn from each other.  

  • Have Fun. Celebrate wins, enjoy daily victories, and bring your energy.

    • Skip writing cover letters. Tell us about your most passionate personal project, your desired salary and your earliest possible start date. We are looking forward to your application!
     
    We welcome applications from people who will contribute to the diversity of our company.
    Apply for this job

    Curious About our Recruiting Process?

    The interview process at applike group is seamless, fast, and fun for you! Recruiting is a two-way street, so that’s why our process is designed for both you and us to get to know each other. Our Talent Acquisition team is there to guide you through the process, making sure you will receive the best candidate experience. The process is usually divided into 5 major steps:
    Recruiting FAQs
    Screening Process
    Simply apply with your updated resume, we don’t need any cover letters or additional documents. If you have a relevant portfolio, you can of course share this as well. After reviewing, we will get in touch with you quickly.
    First Interview
    In the first interview you will meet someone from the Talent Acquisition team to get to know more about the company, our culture and the open role.
    Case Study Step
    We designed this step to get a deeper understanding of your skills and also give you some insights into tasks that might be awaiting you in the new role.
    Final Interviews
    In the final interviews you will get the chance to meet you future Lead, Team and also Managing Director to get the full picture of what it could be like working here.
    The offer
    Finally – after clearing all steps successfully, you are going to receive an offer from our side. Congrats, we want you on our team! … and we hope you accept the offer and join us! 🙂

    Tips & Tricks to Nail Your Interviews!

    mail

    Skip cover letters!

    Since we want to keep everything fast and easy for you, we don’t want you to waste time on a cover letter – we would rather take a look at your CV and if it’s a match, we directly invite you to a chat.
    done_all

    Check your equipment

    Test your internet connection, camera, mic, and speakers beforehand. Time for each interview is limited, and we’d like to spend as much of it as possible on getting to know each other. If the interview is online, always have your camera on! It’s way easier to create a meaningful interaction if we also see each other.
    manage_search

    Do some research!

    We will give you all the information about the role & company’s culture, but it’s always nice to see how you perceive us after doing some online detective work 😉
    elevator

    Prepare an elevator pitch

    We will certainly ask you to briefly summarize your work experiences in a short overview. Think of what you’re going to say beforehand so you can fit all of the essential information in 2-3 minutes. Keep the goal of the interview in mind, and make sure everything you say is relevant to the position you’re applying for.
    fact_check

    Structure your answers

    Be specific, but don´t get caught up in details – following the STAR method can help you: Situation (set the scene and give the necessary details of your example), Task (describe what your responsibility was in that situation), Action (explain exactly what steps you took to address it), Result (share what outcomes your actions achieved).
    person_celebrate

    Let your personality shine

    It is a recruiting process, but this doesn’t mean you can’t loosen up and showcase your personality. We are looking for an authentic character and we are open to having some small talk or a funny joke thrown into the mix. This might even show us that you’re a good cultural fit. Remember, we like to have fun!
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    Be prepared with questions

    At the end of the interview, we will ask you whether you have any questions for us. Use this time to get answers to all your questions or clear out any curiosities. Always have two or three questions prepared, whether about the position specifically or about career development, upcoming projects, or organizational culture.
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    Don’t be afraid of rescheduling

    Even if you’ve already scheduled an interview, urgent things might pop up in your schedule or you might not feel fit to attend the interview. We are all human & we treat these situations with empathy. It´s better to reschedule rather than not be 100% up to attend the interview. Simply communicate the change with your TA Manager and we will find a common solution.

    Finding Home Abroad – Relocation Stories

    We’re supporting new colleagues from all over the world to move to Hamburg, Germany – see what they have to share about their relocation experience:
    Read Relocation Article
    “Unlike other companies, justDice/applike was there for me from the beginning. After signing the offer, I got comprehensive support in getting my visa, finding a temporary apartment in Hamburg & covering travel expenses for my whole family. All of this made our relocation significantly easier and more enjoyable.”
    Grigory – justDice
    relocated from Georgia with spouse
    “Relocating to Hamburg with my family of four was a significant undertaking, but applike’s comprehensive support made the transition smooth and stress-free. From arranging our family’s transfer to assisting with residence permits, Applike’s thorough planning and financial backing ensured we felt welcomed and settled in our new home from day one.”
    Roman – Sunday
    relocated from Kazakhstan with spouse and 2 kids
    “Relocating to another country is challenging, but applike group made the process significantly smoother by providing comprehensive support: from handling paperwork to offering a relocation allowance.”
    Min – justtrack
    relocated from Thailand with spouse
    “My relocation process was supposed to be quick and easy yet we stumbled across delays from the embassy. So, the People team was extremely helpful, providing us with all necessary support with documentation, appointments, and processes; all in order to speed up the process and make sure we get to Germany as fast and as easily as possible.”
    Mia – applike group
    relocated from North Macedonia with spouse
    “Moving to Hamburg was a breeze thanks to adjoe/applike. They managed every detail, from flights to accommodation, and their thorough support made me feel valued even before starting my new role. The entire experience was smooth and memorable, making my transition to this beautiful city unforgettable.”
    Kim – adjoe
    relocated from the Philippines

    Recruiting FAQs

    Frequently asked questions
    How long does your recruiting process take?

    We aim to make our recruiting process as fast and efficient as possible, but the duration can vary depending on the role you are applying for. Usually we are really fast, though (less than 4 weeks).

    Can I apply for more than one role?

    Yes, if you see multiple roles open that match your skill set, you can apply for them simultaneously. Our Talent Acquisition team will review your application and contact you about the role that best seems to match your skills. 

    Can I apply for multiple companies within applike group?

    Yes, if you see multiple roles that match your skill set, you can apply for them simultaneously. Our Talent Acquisition team will review your application and contact you about the role that best matches your skills.

    I just handed in my application, what are the next steps?

    Great! Please allow a few days for our team to review your application. We will contact you with the next steps as soon as possible.

    How is AI used for the recruitment process?

    As part of our hiring process, we may use an AI Notetaker tool to transcribe and summarize interviews. This enables our hiring teams to focus fully on candidates and ensures a fair and well-documented selection process.

    This tool joins interviews as a silent participant and generates a transcript and factual notes. Only those directly involved in the hiring process will have access to this data, which is stored securely and deleted after 6 months.

    Candidates are informed in advance, given the option to opt out, and opting out does not impact the outcome of the application.

    How do I know I’m really being contacted by someone from applike group?

    We’ll never ask you for money, fees, or sensitive information (like bank details, tax forms, or credit card numbers) during the hiring process.
    If anything feels off, you can always double-check by reaching out to our Talent Acquisition team at ta@applike-group.com.
    Once you’ve signed your contract, our HR team may request personal details, but only from our official email: hr@applike-group.com.

    How do I know if the job I want to apply to is legitimate?

    To ensure you are applying for a genuine position, we recommend verifying the opening on our official careers pages (applike, adjoe, etc.). If you prefer, feel free to submit your application directly through our site rather than third-party platforms.

    Do I need to be located in Germany to be able to apply for your jobs?

    No, we do provide full visa and relocation support. 

    Do you help with my relocation?

    We do! You can find more information about our relocation support and the succesful relocation of our colleagues here on this website.

    What if I want to relocate together with my family?

    No problem! Our visa and relocation support does also include your partner or kids. (Please be aware that legal marriage is often times a requirement to obtain a partner-visa).

    Can I work remotely?

    If you prefer 100% remote companies, applike is not the right place for you because we strongly believe in face-to-face collaboration. However, we did implement a hybrid working model where we are in the office at least three days a week (Monday, Tuesday, and Thursday) and can work remotely the remaining two days. Additionally, you get three whole weeks per year to work fully remotely if you want.

    What does hybrid working and flexible working hours mean?

    Our hybrid working approach involves being in the office at least three days a week (Monday, Tuesday, and Thursday) and the option to work remotely the remaining two days. Flexible working hours mean that we work Monday-Friday, but do not have fixed working hours. Just make sure to adapt to the rhythm of your team.

    Where is your main-office located?

    The headquarters of the applike group and all its subsidiaries are located in Hamburg, Germany. We do have offices in the US and APAC.

    What is so great about your office?

    Well next to the fact that you are able to see and collaborate with your colleagues face-to-face, we have a super modern office that leave no wishes open: from Drinks & Snack, areas to work away from your desk to a fully equiped gym.

    Can I really bring my dog to the office?

    Yes, you can!

    Couldn’t find the perfect job offer?

    Nevermind! We are always interested to get in touch with new talents.

    Contact us