Choosing Between HOLLIS for Archival Discovery and Collections Explorer
Last updated: 2025-12-16
As of Fall 2025, two systems are available to search across Harvard’s finding aids for archival collections: HOLLIS for Archival Discovery (HAD) and Collections Explorer (CollEx). Both allow users to search the same archival finding aids, but they differ in search approach and intended use.
The purpose and function of HOLLIS for Archival Discovery is both presenting and making finding aids and all of the associated data and content searchable, accessible, and requestable.
HOLLIS for Archival Discovery and Collections Explorer are complementary tools for discovery; one does not replace or supersede the other. Both systems were developed and upgraded as part of the broader Reimagining Discovery initiative. Harvard is committed to developing and maintaining both HOLLIS for Archival Discovery and Collections Explorer as discovery platforms for special collections.
Collections Explorer is under active development. Future updates will refine search relevance and expand the collections and materials that are searchable, including bibliographic records from Alma and image records from JSTOR Forum/JSTOR Digital Stewardship Service.
This page is designed to help special collections staff understand when to recommend using these systems when assisting researchers.
Development Status
HOLLIS for Archival Discovery (powered by ArcLight) will launch in January 2026. The system will be enhanced over time (e.g. UX improvements, minor search enhancements, potentially new embedded media types), but do not expect major changes and upgrades. The production system will receive nightly updates from ArchivesSpace.
Collections Explorer is under heavy development as search relevance/behaviors, data sources, and data imports are tweaked, enhanced, and built. There will be major changes to the system over time (particularly as new data sources are imported). The system does not currently receive regular updates from ArchivesSpace or LibraryCloud.
Overview
System | Description | Best For |
HOLLIS for Archival Discovery (HAD) | The dedicated system for discovering and browsing finding aids for archival and special collections across Harvard. | Users searching across finding aids to discover material across archival collections that relates to their research topics. Also best for conveying context about an archival collection, consistent search results, and related material. |
Collections Explorer (CollEx)
| A new AI-driven search platform that supports exploratory research across Harvard’s archival and special collections. As of Fall 2025, CollEx includes the same archival finding aids as HAD but will soon include bibliographic records from Alma and image records from Forum. | Users who want to explore new topics, are more comfortable with natural language searches, or want to experiment with broader concept-based searching using an AI-driven search tool. |
How the Search Experience Differs
Feature | HOLLIS for Archival Discovery | Collections Explorer |
Search type | Keyword and fielded search, with ability to group search results by collection | AI-powered semantic search (concept-based) |
Results consistency | Predictable: the same query returns identical search results and order | Due to the use of semantic search results and their order may vary slightly because semantic search interprets meaning rather than matching exact terms. |
Strengths | Discovery, precision, context, access, and consistent search results | Discovery, conceptual exploration, and surfacing unexpected materials |
Data sources | ArchivesSpace: dedicated to archival finding aids | Archival finding aids (additional data sources, such as images, to be added) |
Results Link To | Finding aids and their component records; materials can be requested directly from the interface | Links to records in HOLLIS for Archival Discovery, with AI-generated analysis of its relevancy/contents |
Talking Points: When to Recommend HOLLIS for Archival Discovery
Use HOLLIS for Archival Discovery when a researcher:
Needs to access digital content or request access for a Reading Room visit or copies. From HAD, they can also save findings to their HSR account for later reference or requesting.
Needs authoritative biographical and historical background as well as the context of the full collection contents.
Needs consistency and reproducibility in their searches.
Wants to know that they ”found everything,” including the most recent finding aids
Talking Points: When to Recommend Collections Explorer
Use Collections Explorer when a researcher:
Is working with a librarian and is learning about archival research.
Is exploring a new or interdisciplinary topic and wants to see related materials that may not include direct matches to their search terms.
Wants to try semantic (concept-based) search to surface materials that might not appear in a keyword search.
Is more comfortable with natural language interfaces than keyword search
Is open to experimentation rather than precision.
Example: A researcher searching “migration stories” in Collections Explorer may retrieve collections related to immigration, displacement, or diaspora, even if those exact phrases don’t appear in the finding aids.
Talking Points: Putting Them Together
Collections Explorer is currently experimental and should not be the only avenue for research. Users are encouraged to use Collections Explorer as part of their research, but should use it alongside systems like HOLLIS for Archival Discovery.
HOLLIS for Archival Discovery is a more complete discovery tool than Collections Explorer, is the primary archival and special collections discovery tool and provides the finding aid (or collection guide) content for Collections Explorer. Collections Explorer provides a new and powerful way of locating relevant material in our collections, but is experimental and under active development. Archival research should always include itHOLLID for Archival Discovery as part of the discovery and access process. Collections Explorer provides a new and powerful way of locating relevant material in our collections, but is experimental and under active development.