ATOM (Access to Memory)
AtoM is an open-source, multi-lingual, web-based tool for archival accessioning, arrangement, description, and access. It includes a web-based interface that archivists can use to enter information about repository records, accessions, authority records (for provenance, creators), hierarchical archival descriptions (fonds/collection, record group, series, subseries, item, among others), terms (such as subject and place access points, maintained in controlled taxonomies), and functions. AtoM also includes a web-based user interface that the public can use to search and browse the collection descriptions. See: https://www.artefactual.com/wp-content/uploads/2018/10/AtoM-information-summary-final.pdf  and https://www.artefactual.com/wp-content/uploads/2018/10/AtoM-information-sheet-final.pdf .
Artefactual Systems (New Westminster, BC, Canada) is the lead developer of AtoM and Archivematica. 
Licensing and cost
All AtoM code is released under a GNU Affero General Public License (A-GPL 3.0) and all related resources (such as the documentation, wiki resources, slides, etc.) are freely available under Creative Commons Share-alike licenses (CC-BY-SA 4.0). Users may customize the code themselves, or contract with Artefactual or other vendors to implement new features and enhancements. All modifications should be made available at no cost to other users, per the A-GPL-v3 license.
AtoM 2.0 grew out of the ICA-AtoM system and was first released in October 2013. Version 2.5 was released in May 2019. Generally, since the 2.0 release there has been one major (feature-based) release and one minor (bug-fix and translation update) release per year. The project remains under active development.
Artefactual is also currently collaborating with the newly formed Access to Memory Foundation  to begin preparing high-level design requirements for AtoM 3, a next-generation version of AtoM based on the principles of linked data. Artefactual intends to ensure that there will be an upgrade path from AtoM 2 to AtoM 3, and will continue to maintain AtoM 2 for the foreseeable future, at minimum until there is major feature parity in AtoM 3.
Platform and interoperability
AtoM can run on various Linux distributions and other unix-based platforms, although Artefactual uses Ubuntu long-term support (LTS) releases as the development platform. It can also be installed on Windows and MacOS based servers using virtualization.
Required software includes Nginx (preferred) or Apache, Elasticsearch, Java, MySQL, and Gearman job server. AtoM uses PHP and requires the extensions: cURL, JSON, APC, PDO and PDO-MySQL, and XSL. Other dependencies include ImageMagick, Ghostscript, Ffmpeg, pdftotext (part of poppler-utils) and Apache FOP. Specific versions of those dependencies may vary with the OS and AtoM versions. For more information see: 
AtoM can be installed in a virtual machine if the host computer supports virtualization. Note: older Wintel machines may not support virtualization, and many newer Wintel machines need to have virtualization enabled in the BIOS.
AtoM integrates well with Archivematica, the open source digital preservation system also developed by Artefacual Systems. See Archivematica’s COPTR entry here: .
In general, the first step is to create a description of the archival institution. AtoM allows for multiple institutions to share the same instance, which could be useful for collaboratives or distinct units within larger repositories. A typical workflow would be to create an authority record for the provenance of the collection, accession the fonds/collection (linked to the institution’s record and the provenance record), create a collection-level description, and then add additional levels of description (series, subseries, folder, item).
In some instances, it may make more sense to create folder or item descriptions in an external tool, such as a spreadsheet, and import them to AtoM.
Descriptions and authority records can include links to digital objects (born-digital or digitized records).
AtoM is highly configurable, and almost all terms appearing in drop-down menus and autocomplete fields in the edit templates are terms that users can edit in the related controlled taxonomies, or related entities that can be edited via the user interface. Administrators can also customize menus, default page elements, and configure a number of additional settings that affect the look and behavior of AtoM. The default theme can be customized, and one alternative theme is included at installation for reference, which can be switched via the user interface. More advanced customization may require editing associated style-sheets or PHP code.
Documentation and user support
Extensive documentation on the website a user manual with sections for getting started, adding/editing content, accessing content, creating reports, importing and exporting data, and data entry templates. The Administrator manual includes sections on installation, maintenance, customization, troubleshooting, and security. The Developer manual includes information for programmers who want to modify or develop modules. See: 
AtoM provides an online demonstration site that allows the public to get a feel for both the archivists’ and public interface. Import and upload features are disabled for security purposes. See:  AtoM also provides a preconfigured VirtualBox image that can be easily installed using Vagrant software on most operating systems. This local implementation has all features enabled. (Wintel users should ensure virtualization is enabled in BIOS.) See:  and .
An active User Forum (based on Google Groups) provides a place to ask questions, both technical and functional, as well as learn about software developments. A large user community and AtoM developers participate in the group and offer a significant amount of support for free. See: 
Artefactual also supplies remote technical support, software hosting, software development, custom theming, data migration, training, and consulting for a fee.
The web interfaces for routine use by archivists and the public are relatively intuitive and easy to use. Edit templates are derived directly from national and international standards wherever relevant, and include tooltips to assist users drawn directly from the related standard rules. Institutions may want to create a user manual that describes how local practice is applied when using the system; for example, how to encode reference codes (collection, box, and folders).
Importing data from spreadsheets requires UTF-8 encoded CSV files with proper unix-style line endings - Artefactual recommends using LibreOffice Calc as a spreadsheet application over proprietary products such as Microsoft Excel, which commonly use custom encodings and line endings. CSV import templates are available on the AtoM wiki  and included in AtoM’s code base as well.
Archivists should be familiar with descriptive standards and practice. See Standards Compliance below.
Installation requires knowledge of the operating system and familiarity with the unix command-line, including the ability to install and customize software, file systems and permissions. However, the installation documentation is superb, providing step-by-step instructions that most tech-savvy users can follow. Advanced users and system administrators should not have problems following the instructions.
AtoM supports several descriptive standards, including:
- ISAD(G), 2nd ed. International Council on Archives - Dublin Core, Version 1.1. Dublin Core Initiative - MODS, Version 3.3, US Library of Congress - RAD (Rules for Archival Description) July 2008 version. Canadian Council of Archives - DACS (Describing Archives: a Content Standard), 2nd ed. Society of American Archivists
AtoM also supports ISAAR(CPF), 2nd ed., the ICA’s standard for archival authority records, ISDIAH, 1st ed., the ICA’s Standard for Describing Institutions with Archival Holdings, and ISDF 1st ed. for describing functions.
Data can be imported and exported in EAD 2002 XML (Encoded Archival Description), , MODS XML, DC (simple) XML, EAC-CPF XML (Encoded Archival Context – Corporate, Personal, Family), CSV (comma separated values), and SKOS (Simple Knowledge Organization System).