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We’re in the process of updating the documentation for Zotero 5.0. Some documentation may be outdated in the meantime. Thanks for your understanding.

Direct Access to the Zotero SQLite Database

While it is generally preferable to access Zotero library data via either the Server API or JavaScript API, it is also possible to directly access the SQLite database of the Zotero client using an SQLite client, library, or third-party tool.

Zotero uses mozStorage, a database API backed by the SQLite database engine, offering the power of a relational database system within the Mozilla development environment. All system data and item metadata is stored in an SQLite database, zotero.sqlite, within the Zotero data directory.1)

However, external access to the SQLite database (including direct access via the mozStorage API) should be done only in a read-only manner. Modifying the database while Zotero is running can easily result in a corrupted database, as mozStorage caching breaks the normal file-locking in SQLite that allows for safe concurrent file access. And even if Firefox is shut down before accessing the file, modifying the database directly bypasses the data validation and referential integrity checks performed by Zotero and the Zotero server that are required for Zotero to function properly. Generally, the SQLite database should be viewed as an internal database that has the benefit of being externally readable for people who want to get the data out in other ways.

Also be aware that the SQLite database structure can change between Zotero releases.

Zotero Client Data Model

Each bibliographic record in Zotero has an “item type” (book, journal article, thesis…), a set of fields (author, title, date…), and field values. The selection of fields depends on the item; for instance, a thesis has a “university” field which other items do not have.

Item types and fields are defined in system.sql and translated in In theory you can change and add item types and fields, but this may make your installation of Zotero incompatible with other users and future releases—import routines and citation formats may not work anymore. If you need to add additional information to your records, you should use the “extra” field that is available for all item types. Zotero can be used in many languages, but you should always refer to item types and fields with their internal name as defined in system.sql and used in

In addition to the basic item types and fields, each item can have associated user data as defined in userdata.sql. This includes:

  • a set of notes
  • a set of attachments
  • a set of tags
  • a set of links to related items

Attachments (PDFs, snapshots, etc.) are stored inside the Zotero data directory, in separate subdirectories named after the ID of the item they belong to.

For a comprehensive list of the internal names of fields, their English equivalents, and their CSL mappings, if applicable, see the CSL/Zotero Metadata Field Index. Similar mappings, and the creator roles available for each item type, can be retrieved from the Zotero server API.

Schema Spy

The comprehensive way of learning about Zotero's database structures is by digging into the .sql files. Here is, however, some automatically generated database documentation (created by SchemaSpy):

1) If the database doesn’t exist at browser startup, a new one is created from .sql files in the extension directory, which are then used only during schema updates.
dev/client_coding/direct_sqlite_database_access.txt · Last modified: 2017/12/18 09:02 by bwiernik