Dataharvest 2026 - the European Investigative Journalism Conference

Every investigative journalist has faced the same bottleneck. What would I find if I could check all of them: all the company registrations, all the addresses, all the permits? Until recently, answering that question required weeks of scripting. In this session, we introduce a faster way: directing an AI coding agent to build investigative data pipelines on demand. Participants will direct an agent to pull data from a public source, clean it, and turn it into an interactive visualization, all without writing code manually. The approach is applicable to a range of investigative beats, from financial crime and corruption to environmental accountability and lobbying networks.

To follow along, participants should have a basic understanding of web technologies, but no programming experience is needed. After attending this session, participants will be able to direct an AI coding agent to build a data pipeline, from raw data to interactive visualization, and apply this methodology to their own investigative questions. Participants should have a laptop with a modern web browser. We will provide API keys and access credentials during the session. Detailed setup instructions will be shared via a GitHub repository before the workshop.

Coding has long been a skill journalists wanted to learn to make their investigations more efficient and rigorous. The main barrier was the significant time investment required to develop that skill. But since large language models emerged, we no longer need to write code ourselves. We do, however, still need to make informed choices when instructing an LLM to write code for us. Otherwise, those choices get made for us by the model.

How do we instruct the LLM best? How can we understand a code? And how do we catch potential mistakes? No prior coding knowledge is required to attend this session. You'll learn a simple, systematic approach to conversations, context management, and effective prompting that will help you to code anything.

The participants should either have an account with a subscription to large language model provider such as ChatGPT or Claude and be able to use them locally with Claude Code or Codex. Alternativelly, they should install Open Code (https://opencode.ai) and we will provide them with API keys.

Slides: https://datafrosch.fun/slides/code-anything/

Predictive Markets are on the rise, and with them, easy money for insider knowledge and those who can influence their outcomes. While regulation is slow to catch up, investigations don't have to be. Polymarket is the most well-known of these predictive markets, and one thing that defines it is open data on all exchanges going on in a market.

This session will cover key concepts of Polymarket and the possibilities and limitations of investigating it. It will include basic Python code to extract and analyse its open data, and a new open source user interface tool you can use to quickly understand the market and accounts. In the end, we will learn techniques to identify suspicious actors from a few example markets.

Although some code will be shared during the session, you don't need to have a working knowledge of Python to participate.

Comic-book hero Tintin is, without a doubt, the most famous Belgian journalist who never lived. In the course of his 24 albums, which brought him from the early Soviet Union to the surface of the Moon, Tintin did preciously little *actual writing*, but there are still one or two lessons journalists can learn reading the adventures. ‘

Your hosts for this session have set a "trail" through the Tintin stories, and the legacy of Belgium's most famous boy adventurer. Come and compete in a light-hearted quiz which we hope will help you to fall in love with Herge's creation all over again - this time as a datajournalist!

Unlike some quizzes contestants are encouraged to use their phones or laptops to help them navigate through the questions. No previous knowledge of Tintin is required!

In our digitally connected world, perpetrators feel so safe online that they build their networks openly: on public-access porn websites and messenger apps such as Telegram. Our investigation for STRG_F/NDR in Germany uncovered an international rape network that had formed on porn websites and in dozens of private chat groups on Telegram. One group had more than 70,000 members.

Users exchange detailed information on how to drug and rape women who are already close to them, such as their wives, girlfriends, sisters, or mothers, without them noticing. The rapists share videos and photos of the assaults online. One man from Germany drugged and raped his wife for more than 15 years and generated millions of views with the footage. Our investigation triggered a police investigation, and he was stopped.

We'll share how we began investigating these networks, how we gained access to them, how we investigated the users for years by also going undercover, what tools we used, what ethical and moral challenges we have faced, and how we kept an overview of all the footage we documented and saved over the years.

We will address:
- How do you conduct online research in criminal networks? (Structures, dynamics, and mechanisms)
- How do you gain access to them?  (User's communication and behaviour) 
- What opportunities and limitations did we encounter? (Laws and journalists' rights, ethical and moral responsibilities)
- When should you consider undercover research, and what can it look like? (Journalistic standards and guidelines)
- How do you protect your own mental health when confronted with disturbing content?

The Great Firewall, censorship, and language barriers make open source research on China really difficult, if not impossible. In this session, we aim not only to make you aware of obstacles you may face, but to show you solutions and strategies, especially for journalists and researchers working from outside China who don't speak the language.

We’ll show you the research resources, toolbox and we'll share tips on:

1) how to navigate Chinese social media: WeChat, Douyin, Rednote and others,
2) how to reconcile information inconsistencies in English and Chinese,
3) how to read the ownership of Chinese companies: private, state owned and central government enterprises,
4) mobile device setup and translation applications.

This talk will show the methodology behind The Guardian’s exclusive investigation into properties advertised as tourist destinations on Airbnb and Booking.com located in Israeli settlements that are illegal under international law. The Guardian found 760 rooms being advertised in hotels, apartments, and other holiday rentals in illegal Israeli settlements in the West Bank, as NGOs and activists warned that these companies are violating international law and profiting from war crimes.

In their investigation, they used geospatial tools, like PostGIS and QGIS, to localise accommodations on a specific geographical area, and to join these accommodations with shapefiles representing the borders of illegal settlements to identify those based within settlement boundaries. Using OSINT methods and Google Sheets, they designed a methodology to solve data challenges like duplicate and multi-platform listings, and listings with approximate locations.

In this session, attendees will come up with a robust methodology to find tourist accommodations in any geographical area, so they can reproduce the method for new stories.

Tampermonkey is an age-old browser extension that allows you to inject scripts and stylesheets into any web page, turning the web into your personal playground. We'll look at how to customize your CMS with DIY features, add "Download all" buttons to paginated websites, automate tedious processes like filling out forms and redesign websites however you'd like. Best of all, Tampermonkey scripts are saveable and sharable, allowing you to give other members of your newsroom superpowers without fiddling with distributing extensions or asking them to run Python scripts. To follow along, participants should be able to install extensions in their web browser of choice.

Materials: https://jsoma.github.io/workshop-tampermonkey/

With so-called low-code platforms like n8n, you can quickly click together programs that would otherwise require tedious Python coding. And you can integrate LLMs at various points to, for example, extract information from texts or summarize content. This allows you to build complex workflows. Receive a Teams message from an agent when a nearby river level approaches extreme values? No problem! Automatically monitor the police website for accident reports and generate suggestions for brief news items? With n8n, this can be automated quickly. This workshop provides an introduction to the free platform n8n. No prior knowledge is expected.

Materials: https://github.com/chesselingfm/dataharvest26-n8n

Police work is notoriously difficult to investigate. While police actions directly affect fundamental rights and guide politics and law-making, official data on their influence is scarce.

In this session, we will share some tools and methodologies on how to investigate the police sources. We will draw on more than ten years of investigations into different aspects of police violence and state abuse of power in Germany. We will also show how the data-driven journalism tools can help to make the underlying structures more visible, and present our recent investigation into police unions in Germany: who they are, want they stand for and how they influence the public debate and politics. We pieced together data from different sources and combined it with investigative journalism to draw the full picture.

We want to show how it is possible to do a data-driven investigative story despite missing data. We will focus on the following questions:

- How to build your own datasets when no official statistics exist? Which public data sources about the police are available? Which data can we get from ministry inquiries? What about social media?
- How to clean up, classify and analyze the data? Which tools are helpful in combining manual and automated workflows?
- How to tell a complex data-driven story without this one headline? What are judicial and editorial hurdles when publishing a sensitive topic?
- What can investigative and data journalists gain from close collaboration? What worked well? What would we do differently?

This session provides a practical guide for using Automatic Identification System (AIS) data to investigate maritime irregularities. Our case study will be the Russian shadow fleet. The session is beginner-friendly, while the second case study will also be interesting to advanced AIS users and people with programming skills.

In the course of the session, we will present two case studies demonstrating how AIS data can be used to investigate the Russian shadow fleet.

The first case study will show how to use AIS data and vessel metadata to evaluate the environmental risk of shadow fleet traffic. The second is a recent investigation of Greenpeace Italy exposing a new ship-to-ship (STS) transfer hub off the coast of Sicily, revealing multiple sanctions breaches and a lack of oversight by Italian authorities. The investigation triggered two parliamentary inquiries and an investigation by the Chief anti-Mafia Prosecutor and was reported on extensively across national media.

This case study will showcase how the automatic STS detection in MarineTraffic, combined with network analysis (JavaScript, Gephi) and OSINT sources, can be used to trace chains of transfers that bring Russian oil into European ports.

Our session will offer a pro user's look into different proprietary and open-source AIS data platforms and evaluate their affordances (e.g., data export options, alerts, analytics functions), both with and without login. We will give an overview of additional data sources to cross-validate and enrich AIS data (Equasis, ITF Seafarers, IMRRA, order books, class society databases, IGPANDI) and share an internal tool we developed to access these sources automatically.

Participants will leave with practical knowledge of which AIS platforms to use for specific investigative needs, what open-source alternatives exist, and how to apply these tools in combination with network analysis and OSINT sources to uncover maritime irregularities.

This session is based on a case from Serbia, where we managed to identify a person whose identity Serbian authorities and pro-government media actively tried to hide. Starting from a blurred face in a leaked video, we combined basic OSINT with business registries, social networks, geolocation, face recognition tools, dark web email searches, and simple AI-assisted image analysis. We will walk the audience through each phase of the process,  and explain what worked, what failed, and how one can verify findings when evidence is being altered or erased in real time.

Attendees will leave with a practical workflow they can reuse in their own investigations: how to move from a fragment of visual evidence to a confirmed identity, how to cross-check business data with social platforms, how to use face search and morphological comparison safely, how to track digital behavior after supposed arrests, and how to document disappearing online traces before they are wiped. The goal is to share a method that can travel across borders and work in any country where power structures try to keep people invisible.