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Data Scientist, Fraud detection in Barcelona


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Job Description

At Wallapop we are on a quest to grow the collaborative economy and make the world more sustainable by extending the life of products. Would you like to join the talented team that is making this possible?

We are looking for a talented, experienced and enthusiastic Data Scientist to join our Analytics team. As a Data Scientist you will work closely with the Trust and Safety team and our engineers to develop detection and prediction systems and ways to mitigate fraud, to continuously monitor trends in fraud practices, and to use data sources better to enhance our current systems.

Key responsibilities

  • Analyze large datasets to bring valuable insights that identify and predict fraudulent behavior and allow Wallapop to be protected against policy violations and loss of trust.
  • Understand how fraud affects other consumers and work across other teams to give valuable insights
  • Work closely with business and product teams to turn insights into actions.
  • Identify the need and develop statistical models and machine learning solutions that help with fraud detection and prevention from concept to production


  • Master’s degree in data science or equivalent professional experience
  • 2+ years of experience as a data scientist or similar role preferably for a web/mobile company
  • Technical competencies:

o   Data manipulation and exploration tools: SQL, python, pandas, jupyter notebooks

o   Experience in building and tuning machine learning models with most common libraries/frameworks: sci-kit, tensorflow, AWS Sagemaker

o   Deep knowledge and understanding of one of NLP, Image Processing or graph analytics (e.g word embeddings, CNNs, RNNs, etc.)

o   Experience with big data and cloud technologies

o   Data visualization tools (e.g. Looker, Tableau, Qlikview, etc)

o   Previous experience in product analytics and A/B testing

  • Strong user empathy to understand the real question behind a loosely defined business request.
  • Experience in fraud detection and prevention is a great plus although not mandatory
  • Classifieds industry knowledge is a big plus

We offer

✦ All-new, modern and inspirational office space

✦ Flexible working hours

✦ Specialized training

✦ Encouraging, fun and team-focused offsite trips twice a year

✦ International team (now 11 nationalities and counting)

✦ Team building activities

✦ English/Spanish lessons

✦ Half-day Fridays

✦ Free coffee, and free fresh fruit

✦ Private Health Insurance

✦ Other benefits paid from the gross salary (kindergarten check, food check, transport check).


About Wallapop

  • Classifieds

  • Privately Held

  •  Barcelona, Spain

  • 50-100 employees

  • 2013

Wallapop is your mobile flea market, where you can make money from your old stuff and buy great new things.

Wallapop is a pure mobile marketplace that helps people find the best opportunities to buy and sell nice things nearby. But beyond that, what we really want to do is offer the best street trade experience to all our users around the world. In order to achieve this we are looking for some special people...  

  • - Amazing office space.
  • - Apple or PC equipment of your choice.
  • - Specialised training.
  • - Health insurance.
  • - Amazing offsites twice a year.
  • - International team (now 10 nationalities) .
  • - Help with apartment searches.

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