Daejeon, July 27–31
Figure 1: Main View of the Comparative Document Reader with (A) tab bars with options (B) document selector, (C) textual representation of the documents, and (D) word cloud visualization of typical topics.
Eighty years after the end of Nazi Germany, fewer and fewer people have detailed knowledge about the atrocities committed then. At the same time, renewed extremist tendencies showing in politics underline the urgency of preserving and providing meaningful access to survivors and witness testimonies. The MEMORISE project (Jänicke et al. 2024) focuses on digitally safeguarding and analyzing tangible and intangible cultural heritage tightly linked to Nazi persecution and the Holocaust to support sustained remembrance. Therefore, it adds on to ongoing initiatives supporting access to and preservation of cultural heritage reflecting those atrocities with emphasis on the experiences of victims.
Previous works created different digital archives of Holocaust documentation (Yad Vashem 2025, USHMM 2025) and connected fragmented metadata (EHRI 2025). These infrastructural projects were followed by a range of tools to ease access to this data.Previous works created different digital archives of Holocaust documentation (Yad Vashem 2025, USHMM 2025) and connected fragmented metadata (EHRI 2025). These infrastructural projects were followed by a range of tools to ease access to this data.
Some of those offer insights into the data in a free but unguided manner (Jänicke 2024, Seirafi et al. 2025) or in storytelling fashions (Benardou et al. 2022, Christoffersen et al. 2025, Hall et al. 2024, Jänicke 2023, Koehl et al. 2021, Kusnick 2024, Meffert et al. 2024, Oliva et al. 2014, Østergaard et al. 2024). Those projects usually research education of the general public on the Holocaust and the ethical and inclusive access (Ebbrecht-Hartmann et al. 2025). Fewer tools were specifically designed for researchers and their scholarly work with the data (Khulusi et al. 2022).Some of those offer insights into the data in a free but unguided manner (Jänicke 2024, Seirafi et al. 2025) or in storytelling fashions (Benardou et al. 2022, Christoffersen et al. 2025, Hall et al. 2024, Jänicke 2023, Koehl et al. 2021, Kusnick 2024, Meffert et al. 2024, Oliva et al. 2014, Østergaard et al. 2024). Those projects usually research education of the general public on the Holocaust and the ethical and inclusive access (Ebbrecht-Hartmann et al. 2025). Fewer tools were specifically designed for researchers and their scholarly work with the data (Khulusi et al. 2022).
Motivated by this, we present the Comparative Document Reader (CDR), a web-based environment for efficient comparative reading and analysis of multilingual concentration-camp diaries.
Its main contributions are:Its main contributions are:
The CDR focuses on diaries written by concentration-camp prisoners. Diaries are ego-documents written contemporaneously under conditions of uncertainty, offering situated perspectives that differ from post-war testimonies. They are highly valuable for researching prisoners’ in situ perspectives on camp life. Yet, their effective use is impeded by heterogeneity, partial availability, and the sensitivity of contents. While some diaries are traditionally published as books, much of the broader corpus remains dispersed in archives or subject to access restrictions, creating high cognitive and logistical overhead for historians attempting comparative analysis.
The data corpus includes hitherto 88 documents from Bergen-Belsen and Kamp Westerbork, resulting in 2,034 daily entries. Due to the camps' transit function, comparatively many prisoners were able to write diaries. While keeping their personal belongings meant access to utensils, documenting camp life was still forbidden. Prisoners wrote in secrecy, hid, and even destroyed their writing. The data corpus includes hitherto 88 documents from Bergen-Belsen and Kamp Westerbork, resulting in 2,034 daily entries. Due to the camps' transit function, comparatively many prisoners were able to write diaries. While keeping their personal belongings meant access to utensils, documenting camp life was still forbidden. Prisoners wrote in secrecy, hid, and even destroyed their writing.
The corpus is linguistically diverse, which both broadens perspectives and introduces challenges for translation and processing. The formats vary from transcriptions in digital form to difficult-to-read scans of the original, fragile, manuscripts on paper-saving micro-writing. This is further complicated by visual quality issues (see Figure 2).The corpus is linguistically diverse, which both broadens perspectives and introduces challenges for translation and processing. The formats vary from transcriptions in digital form to difficult-to-read scans of the original, fragile, manuscripts on paper-saving micro-writing. This is further complicated by visual quality issues (see Figure 2).
Figure 2: Example pages of diaries showing visual issues: (A) Jósef Gitler (Gitler 2015) with part of the page ripped off; (B) Tiberius Ehrenfeld with entries in an unusual format and partly smeared (unpublished); and (C) Renata Laqueur (Laqueur 2008) with crossed parts and words cramped between crossed-out parts.
Addressing traditional challenges in working with historical ego documents, the core of the CDR is the digital presentation of textual data, both for close-reading and analysis. With a target group of historians first and a general interested public second, the CDR offers quality-of-life features exceeding analog reading experiences, as well as features specifically designed to support document comparison and analysis. To describe these, we will utilize task names from the Task Classification vocabulary by Brehmer and Munzner (2013).
The central space of the visual representation is dedicated to the Textual Representation of the diaries (see Figure 1C), allowing traditional front-to-back reading experiences (consume)–similar to physical books–with the added benefits of digital text formats, such as not having to turn pages or text search. This is complemented by the search feature, allowing users to quickly locate or look up specific terms or concepts across multiple diaries.
A Tag Cloud Visualization (Figure 1D) augments the view by highlighting the most frequent terms in single diaries (A Tag Cloud Visualization (Figure 1D) augments the view by highlighting the most frequent terms in single diaries (query). It helps readers quickly identify common topics and access relevant diary entries through click interactions.
As a tool conceptualized for comparative reading, the CDR allows side-by-side comparison of multiple diaries. The textual view space can be separated into multiple columns, each allowing for various tabs of diaries to be selected. This scalable column layout makes it easy to switch between diaries and to As a tool conceptualized for comparative reading, the CDR allows side-by-side comparison of multiple diaries. The textual view space can be separated into multiple columns, each allowing for various tabs of diaries to be selected. This scalable column layout makes it easy to switch between diaries and to compare their texts directly.
A strong digital advantage beyond A strong digital advantage beyond search is the option to semantically scroll multiple documents in parallel, meaning that when scrolling in one document, all other open documents automatically scroll to entries written at the closest date. This synchronization is key for reading the documents side by side rather than front to back, allowing direct comparison of different perspectives on the same events throughout locations. This approach allows users to consume massive volumes of parallel text in unprecedented form, unlocking siloed memories and weaving previously fragmented narratives into one coherent story.
To compensate for the loss of context in sideways reading, integrated annotations provide quick access to supplementary information, including term explanations and historical context.To compensate for the loss of context in sideways reading, integrated annotations provide quick access to supplementary information, including term explanations and historical context.
Figure 3: CalendarView, showing all documents (A) with zoomed in view on January 1945 (B), with hover interactions highlighting documents for a specific date (C), and all entries to a hovered document (D).
To support crucial understanding of temporal distributions of diary entries, the CDR reimplements the CalendarView by Khulusi et al. (2022). This presents diary entries in a calendar format, allowing users to identify patterns and summarize trends across multiple diaries quickly. In contrast to the prior implementation, the CDR enables dynamic year ranges and removes the previous limit of diaries. For this, a transfer function maps colors (Harrower et al. 2003), extending dynamically with an RGB-shift if needed.
Besides allowing users to get a visual Besides allowing users to get a visual overview of dates covered by diaries (explore) or in which intervals specific authors wrote (locate), it also allows for interactions (see Figure 3): Clicks redirect the user to the Textual Representation tab, with all diaries opened on the selected date (lookup).
To avoid interrupting users' actual workflow, the previous configuration of open documents is saved and can be restored with a single click.To avoid interrupting users' actual workflow, the previous configuration of open documents is saved and can be restored with a single click.
To further support analysis, especially in large corpora, the CDR offers a Global Search feature. While a common feature of digital text readers, its availability is crucial for the CDR to enable users to quickly locate specific terms or concepts and directly access relevant text passages (see Figure 4). The plain text search is also enhanced by the holistic, multimodal MEMORISE knowledge graph, offering a controlled vocabulary thesaurus for named entity recognition, explanations, topic extraction from paragraphs, and more (Mireles et al. 2023) to explore and browse the corpus beyond traditional reading.
Figure 4: Comparison of multiple diary entries using different meanings of the term "Ankunft" (arrival). (A) Arrival of Allied Forces during liberation; (B) Arrival of the Messiah; (C) Arrival of new prisoners in the camp; (D) Arrival of officials deciding possible exchange candidates.
While we developed the CDR with preliminary access to the diary corpus, scattered usage and publication rights for the diaries exist. We originally planned to host the CDR online and open access, but during recent planning stages, we made juristical decisions to gatekeep the tool’s instance with data. Many of the diaries may be used for strictly academic purposes but are forbidden to (re-)publish online without any control over who accessed them or why. Given the sensitive nature of the documents and the potential for uncensored access to personal information about (mostly) relatives, this is understandable. Still, this limitation is hindering the intended accessibility of concentration camp prisoners’ stories.
To still allow usage of the tool, we decided to deploy CDR instances at different on-site access points. This enables researchers and visitors to memorials or research institutions to use the CDR.
Preliminary testing sessions and presentations (academic conferences (Expo 2025), expert workshops (Workshop 2025), and public exhibitions (Ebbrecht-Hartmann 2024, Expo 2023)) showed an overwhelmingly positive reception of both researchers and casual visitors. Historians especially appreciated the ability to quickly compare multiple diaries side-by-side and closely map their analog workflow while also offering a range of digital features. This includes the synchronized scrolling feature, which significantly enhances their ability to analyse and interpret the texts in unprecedented ways. A formal user study with casual users is planned but needs to be postponed due to the very limited public usage rights for the historical diaries.Preliminary testing sessions and presentations (academic conferences (Expo 2025), expert workshops (Workshop 2025), and public exhibitions (Ebbrecht-Hartmann 2024, Expo 2023)) showed an overwhelmingly positive reception of both researchers and casual visitors. Historians especially appreciated the ability to quickly compare multiple diaries side-by-side and closely map their analog workflow while also offering a range of digital features. This includes the synchronized scrolling feature, which significantly enhances their ability to analyse and interpret the texts in unprecedented ways. A formal user study with casual users is planned but needs to be postponed due to the very limited public usage rights for the historical diaries.
As the surviving victims and witnesses of the Holocaust get older and older, it becomes increasingly urgent to preserve their stories and make them accessible. The Comparative Document Reader (CDR) represents a significant advancement in digital non-traditional reading and analysis, particularly in Holocaust research, by providing a robust framework for the analysis and comparison of diverse documents. As a web-based tool, it offers quick and easy access to both, the actual texts as well as visualizations, which ease the approach, enhance understanding and engagement with critical historical records.
This allows exploration and interpretation of these accounts in a more interactive and meaningful way, ensuring their accessibility and preservation, leveraging the digital affinity of younger generations, and helping them connect with the past.This allows exploration and interpretation of these accounts in a more interactive and meaningful way, ensuring their accessibility and preservation, leveraging the digital affinity of younger generations, and helping them connect with the past.
While this paper concentrates on the presentation of diaries, the CDR opens up possibilities for analyzing a wider range of documents, including letters, official reports, personal narratives, and other textual artifacts from different historical contexts. This adaptability underscores the tool's potential to contribute significantly to various fields within the digital humanities, fostering a deeper understanding of processes through enhanced document analysis, alignment, and comparison.While this paper concentrates on the presentation of diaries, the CDR opens up possibilities for analyzing a wider range of documents, including letters, official reports, personal narratives, and other textual artifacts from different historical contexts. This adaptability underscores the tool's potential to contribute significantly to various fields within the digital humanities, fostering a deeper understanding of processes through enhanced document analysis, alignment, and comparison.