Zotero Dev Rules

Zotero is an open-source reference manager. Developers extend it three ways: the Web API (https://api.zotero.org) for online libraries, plugins / the internal JavaScript API for the desktop client, and translators (JS scrapers/converters). Citations come from CSL styles via citeproc-js. This skill mirrors https://www.zotero.org/support/dev so you can answer Zotero dev questions and build integrations without re-fetching.

When to use this skill

• Reading from / writing to a Zotero library over the Web API (items, collections, tags, searches).
• File attachment upload, full-library or partial syncing, streaming (WebSocket) updates, OAuth.
• Building or debugging a Zotero plugin (7–10 bootstrapped era; Zotero 10 migration notes included); scripting the client via its JavaScript API / Run JavaScript.
• Finding an existing open-source plugin with similar functionality (to study its code) before building a new one.
• Writing or fixing a translator (web/import/export/search) and testing it in Scaffold.
• Creating or editing CSL citation styles; working with citeproc-js / citeproc-node.

Reference index — load the file you need

Cheat sheet — Web API

# Read (public library needs no key). HTTPS only. Always pin the version.
curl -H "Zotero-API-Version: 3" -H "Zotero-API-Key: <KEY>" \
  "https://api.zotero.org/users/<userID>/items?format=json&limit=25"

# Library prefix: /users/<userID> or /groups/<groupID>
# Common params: format=json|atom|bib|keys|versions, include=bib,citation, q=, itemType=, tag=,
#                sort=, direction=, limit=1..100 (def 25), start=, since=<version>
# Response headers: Last-Modified-Version, Total-Results, Link (rel=next/last), Backoff
# Rate limits: honor Backoff; on 429 wait per Retry-After.

# Write (key with write access). Up to 50 objects/request. Must carry a version.
curl -X POST -H "Zotero-API-Key: <KEY>" -H "Content-Type: application/json" \
  -H "If-Unmodified-Since-Version: <libVersion>" \
  -d '[{"itemType":"book","title":"..."}]' \
  "https://api.zotero.org/users/<userID>/items"
# PUT replaces (omitted fields cleared); PATCH merges (only changed fields). 412 = version mismatch.

// Client internal JS API (Run JavaScript / plugin). Most DB/disk/network calls are async.
let item = new Zotero.Item('journalArticle');
item.setField('title', 'Example');
item.setCreators([{ creatorType: 'author', firstName: 'Jane', lastName: 'Doe' }]);
await item.saveTx();                               // async, own transaction
let items = ZoteroPane.getSelectedItems();         // window scope

Key endpoints: /itemTypes /itemFields /itemTypeFields?itemType= /itemTypeCreatorTypes?itemType= /creatorFields /items/new?itemType= · full schema: https://api.zotero.org/schema.

Hard rules

• Always pin the API version with Zotero-API-Version: 3 (production) — never rely on the default. Pass keys via the Zotero-API-Key header (or Authorization: Bearer), not the key= query param.
• Every write must carry a version (If-Unmodified-Since-Version header or per-object version). Missing → 428; mismatch → 412 Precondition Failed (re-fetch, merge, retry). Batch max 50 objects.
• Respect rate limits: obey the Backoff header proactively; on 429 wait Retry-After and slow down.
• mtime is in milliseconds, not seconds. File upload is a 3-step flow (authorize → S3 → register); new attachment uses If-None-Match: *, replacement uses If-Match: <previous-md5>.
• Client JS API is async: await saveTx() / getAsync() / Zotero.DB.executeTransaction(...). Use saveTx() for single saves; wrap batches in one transaction. Get the Zotero object via chrome://zotero/content/include.js.
• Translators: metadata block + functions + test cases; detectWeb returns a type / "multiple" / false; finish items with item.complete(). Use promise helpers (requestText/JSON/Document). Licensed AGPL v3; submit via PR to zotero/translators. Test in Scaffold.
• Syncing is version-based: treat the library version as an opaque monotonic integer; use ?format=versions + ?since= to diff, store pristine JSON snapshots for 3-way merge, restart the pass if Last-Modified-Version changes mid-sync. New local objects start at version 0.
• Citation styles use CSL + citeproc-js; submit styles to the citation-style-language/styles repo per its CONTRIBUTING guidelines — don't hand-roll a citation formatter.