# defter
A self-hosted Zotero sync and file storage server: keep one Zotero library in
sync across your machines — metadata **and** attachment files such as PDFs —
without [Zotero Storage](https://www.zotero.org/storage). Metadata lives in SQLite, files in S3-compatible object
storage (Hetzner Object Storage, AWS S3, Cloudflare R2, RustFS, …). Stock Zotero 10 clients sync against
it, and [commonmeta](https://codeberg.org/front-matter/commonmeta-rs)'s `sync`
command can enrich the library through the same API.
**Status: early development (0.3).** The sync protocol, file storage and query
API are implemented and tested; interfaces may still change.
defter builds on [zhost](https://github.com/mulatta/zhost) (MIT, see
`NOTICE`), which worked out the subset of the Zotero Web API v3 a client
needs. defter swaps PostgreSQL for SQLite (rusqlite), `rust-s3` for the
`object_store` crate, and adds a web UI and the endpoints `commonmeta sync`
uses.
## How it works
- **Client redirect, no patching.** Zotero reads its sync server from the
hidden pref `extensions.zotero.api.url`; pointing it at defter redirects
sync and login.
- **Server.** A Rust/[axum](https://github.com/tokio-rs/axum) service. Library
objects are stored as opaque JSON keyed by `(kind, key)`, with the columns
queries need derived on every write. One library version counter, bumped by
each write, keeps the client's `since` reads and `If-Unmodified-Since-Version`
writes coherent.
- **Files.** Uploads stream through defter, which checks the md5 while writing
them to the bucket; downloads redirect to a short-lived pre-signed URL, so
the bytes come straight from the bucket.
- **Auth.** One user, one library. API keys are configured, each read/write or
read-only. The Zotero client gets a read/write key through its browser login,
which you approve on defter's login page by entering that key.
- **Web UI.** A dashboard (library statistics, storage, connection
instructions), shown after signing in with an API key, and the login
consent page for Zotero, rendered on the server from
[askama](https://askama.rs) templates and styled with Tailwind CSS.
[htmx](https://htmx.org) refreshes the dashboard in place; every page works
without JavaScript and is served under a strict Content-Security-Policy.
The full contract is in [`docs/api.md`](docs/api.md).
## Running
```sh
cargo install --path . # or: cargo install defter
defter start --public-url https://zotero.example.org \
--s3-bucket <your-bucket> \
--s3-endpoint https://fsn1.your-objectstorage.com --s3-region fsn1 \
--s3-access-key-id-file /etc/defter/s3-access-key-id \
--s3-secret-access-key-file /etc/defter/s3-secret-access-key
```
Every flag has a `DEFTER_*` environment variable; see `env.example` and
`defter start --help`. S3 credentials also fall back to the standard `AWS_*`
variables. Without `--s3-bucket`, files go to `<data-dir>/files` — fine for
development, not meant for production.
### API keys
The simplest setup is one read/write key in the environment, e.g. in
`/etc/defter/env`:
```sh
DEFTER_API_KEY=<output of: openssl rand -hex 32>
```
When Zotero logs in, it opens defter's login page in the browser; you approve
the login by entering that key, and Zotero receives it. Anyone can start a
login, so the key is what protects the library: generate it, don't choose it
(defter warns about keys shorter than 32 characters), and keep the file
readable by root and the `defter` group only.
To give scripts or agents read-only access as well, provision keys as files
instead, each read/write or read-only:
```sh
openssl rand -hex 32 > app-key # read/write, for Zotero
openssl rand -hex 32 > cli-key # read-only
defter start --keys rw:/path/app-key,ro:/path/cli-key …
```
With no key configured at all, defter generates a read/write key in
`<data-dir>/api-key`; `defter key` prints it.
### Deployment
defter listens on `127.0.0.1:8189`; put it behind a reverse proxy with HTTPS
and set `--public-url` to the proxy's address. The data API is protected by
keys and safe to expose, and so is `/login`, which hands out a key only to
whoever enters one. The dashboard (`/`) shows a sign-in form until an API key
is entered (a read-only key is enough), and `/ui/status` takes the key as a
header. Behind an SSO proxy, add `--login-authorized-user you@example.org` to
also require its identity on login approval.
Clients download from pre-signed URLs on `--s3-endpoint`, so the bucket
endpoint must be reachable from them; otherwise add `--proxy-downloads`.
### Debian with systemd
As root, with Rust installed through [rustup](https://rustup.rs):
```sh
# the binary, straight to /usr/local/bin (the service cannot run one from ~);
# chmod in case a restrictive umask (e.g. 027) made it unreadable to defter
cargo install --locked --root /usr/local defter
chmod 0755 /usr/local/bin/defter
useradd --system --no-create-home --shell /usr/sbin/nologin defter
install -d -m 0750 -o root -g defter /etc/defter
# env.example and defter.service from this repository:
install -m 0640 -o root -g defter env.example /etc/defter/env # then edit it
# the S3 keys, one line each, root:defter 0640:
# /etc/defter/s3-access-key-id, /etc/defter/s3-secret-access-key
install -m 0644 defter.service /etc/systemd/system/defter.service
systemctl daemon-reload && systemctl enable --now defter
journalctl -u defter -f
```
To upgrade: `cargo install --locked --root /usr/local defter` and
`chmod 0755 /usr/local/bin/defter` again, then `systemctl restart defter`.
A binary the `defter` user cannot execute makes systemd fail with status
203/EXEC (behind Cloudflare: error 525).
[`defter.service`](defter.service) runs defter as the `defter` user with its
data in `/var/lib/defter` (systemd's `StateDirectory`, which defter picks up
without `--data-dir`) and the rest of the file system read-only.
### Sharing port 443 with dragoman
On a machine where [dragoman](https://codeberg.org/front-matter/dragoman)
already serves HTTPS on port 443 behind a CDN, defter needs no port, proxy or
certificate of its own: dragoman's `--sni-route` passes connections for
defter's hostname, still encrypted, to defter, which serves HTTPS on a
loopback port with the same CDN origin certificate (if it covers defter's
hostname, e.g. `*.example.org`).
```sh
# dragoman (/etc/dragoman/env), then restart it:
DRAGOMAN_SNI_ROUTES=defter.example.org=127.0.0.1:8443
# defter (/etc/defter/env):
DEFTER_PORT=8443
DEFTER_PUBLIC_URL=https://defter.example.org
DEFTER_TLS_CERT=/etc/defter/origin.pem
DEFTER_TLS_KEY=/etc/defter/origin-key.pem
```
Give defter its own copy of the certificate and key, readable by its group:
```sh
install -m 0644 -o root -g defter /etc/dragoman/origin.pem /etc/defter/origin.pem
install -m 0640 -o root -g defter /etc/dragoman/origin-key.pem /etc/defter/origin-key.pem
```
With the hostname proxied by the CDN, its limits apply to uploads through
defter (Cloudflare: 100 MB per request on the Free and Pro plans), so set
`DEFTER_MAX_UPLOAD_MB=100` there; downloads come from the bucket directly.
Without a CDN in front of defter's hostname, let defter get its own certificate
from Let's Encrypt, as dragoman does, instead of giving it `DEFTER_TLS_CERT` and
`DEFTER_TLS_KEY`:
```sh
# defter (/etc/defter/env):
DEFTER_PORT=8443
DEFTER_PUBLIC_URL=https://defter.example.org
DEFTER_DOMAIN=defter.example.org
DEFTER_EMAIL=you@example.org
```
The TLS-ALPN-01 challenge needs no port 80: Let's Encrypt connects to port 443
with defter's hostname, and dragoman passes that through like any other connection.
So port 443 must be open to everyone, not only to a CDN, and the hostname's DNS
must point straight at the server. Certificates renew by themselves and are kept
in `<data-dir>/acme` (`DEFTER_ACME_CACHE`). Set `DEFTER_ACME_STAGING=true` to try
the setup without Let's Encrypt's rate limits; browsers don't trust those
certificates, so delete the cache directory when switching back.
The server must also reach Let's Encrypt. Its ACME client tries addresses in the
order the system returns them and has no timeout of its own, so where IPv6 is
configured but broken, an order stalls without an error while HTTPS fails with
`access denied`. defter checks this at startup and logs a warning, and warns again
if there is no certificate after five minutes. Fix IPv6, or prefer IPv4 by adding
`precedence ::ffff:0:0/96 100` to `/etc/gai.conf`. To see the order's progress, set
`RUST_LOG=defter=info,rustls_acme=info`.
### Hetzner Object Storage
[Hetzner Object Storage](https://www.hetzner.com/storage/object-storage/)
is the intended storage, for a defter running at home as well as for one
later deployed on a Hetzner Cloud server.
1. In Hetzner Console, create a project, a **private** Bucket in one location
(`fsn1` Falkenstein, `nbg1` Nuremberg or `hel1` Helsinki), and S3
credentials for the project (shown once: save both keys). Keys are valid
for every Bucket of the project, so give defter a project of its own.
2. Start defter with the location as both endpoint and region:
```sh
defter start \
--s3-bucket <your-bucket> \
--s3-endpoint https://fsn1.your-objectstorage.com --s3-region fsn1 \
--s3-access-key-id-file ~/.config/defter/s3-access-key-id \
--s3-secret-access-key-file ~/.config/defter/s3-secret-access-key
```
defter addresses Hetzner Buckets by host name
(`https://<bucket>.fsn1.your-objectstorage.com`), which its pre-signed
download URLs need.
3. Check the round trip: `DEFTER_KEY=$(defter key) scripts/smoke-s3.sh`.
Costs (Hetzner's prices, November 2026, excl. VAT): €6.49 a month includes
1 TB of storage and 1 TB of outgoing traffic; uploads and S3 requests are
free. Downloads by pre-signed URL count as outgoing traffic. Objects under
64 KB are billed as 64 KB.
For a later deployment on a Hetzner Cloud server, put the server in an EU
location: it is then in the Bucket's network zone (`eu-central`), and traffic
between them is free. With `--proxy-downloads`, files then reach clients
through the server, whose traffic allowance is separate from the Bucket's.
### Connecting Zotero
defter requires **Zotero 10** (desktop). Earlier versions are not supported.
defter syncs **My Library** only. Group libraries stay on zotero.org: a
Zotero that syncs with defter no longer syncs its groups, and asks whether to
keep or remove the local copy of each.
> [!WARNING]
> Connect defter only to a **new, empty data directory**. Zotero treats
> logging in to defter as switching accounts: if the data directory was
> synced with another account (zotero.org) before, Zotero **deletes its local
> libraries** and restarts; it does not combine them with the defter library.
> Moving an existing zotero.org library to defter is not supported yet.
Use a separate Zotero profile with its own data directory, so the zotero.org
library stays untouched in the default profile:
1. Close Zotero, back up the existing data directory (Settings → Advanced →
Files and Folders → Show Data Directory) and profile, then start the
profile manager with `zotero -P` (macOS:
`/Applications/Zotero.app/Contents/MacOS/zotero -P`) and create a profile,
e.g. `defter`.
2. In the new profile, Settings → Advanced → Files and Folders → Data
Directory Location → Custom: a new, empty directory (e.g.
`~/Zotero-defter`; check the path, a typo creates another empty one), then
restart Zotero. Do not log in to zotero.org in this profile.
3. Settings → Advanced → **Config Editor** (accept the warning), then set:
```
extensions.zotero.api.url = https://defter.example.org/api/
extensions.zotero.streaming.enabled = false
```
Keep the trailing slash: Zotero appends paths such as `keys/sessions`
directly. defter has no streaming server, hence the second setting.
4. Restart Zotero.
5. Settings → Sync → **Log In**. Zotero opens defter's login page in the
browser; enter an API key that may write and click Approve. Zotero picks
up the key within seconds; the login request expires after 10 minutes.
6. Keep file syncing set to **Zotero** (Settings → Sync → File Syncing):
attachment files then go to defter, and through it to the bucket.
Run one profile at a time; start the one you need with `zotero -P <name>`,
or from the profile manager.
To point a profile back at zotero.org, reset both settings in the Config
Editor (right-click → Reset) and restart Zotero; logging in then switches
accounts again, which deletes the local defter library (it stays on the
server).
### commonmeta sync
`commonmeta sync` enhances the items of a Zotero library with what the
commonmeta store knows about them. defter serves the API it uses under
`/api`; [`docs/commonmeta-rs-changes.md`](docs/commonmeta-rs-changes.md)
lists the commonmeta-rs changes needed for it to target a remote server (it
currently only talks to `http://localhost:23119/api`).
Until then, `commonmeta sync` works through Zotero desktop, which syncs the
changes to defter. This also fills a new, empty defter library for testing,
for instance with the works of an ORCID record:
1. Start Zotero in the profile connected to defter. Only that profile may be
running: the local API belongs to whichever Zotero is open, so with the
default profile open, commonmeta writes to the zotero.org library.
2. In that profile, enable Settings → Advanced → **Allow other applications
on this computer to communicate with Zotero**. The setting is per profile,
so a new profile has it off (commonmeta then reports "Zotero's local API is
off"). Check with
`curl -s -o /dev/null -w "%{http_code}\n" http://localhost:23119/api/`,
which prints `200`.
3. Look first, then write a few works, with up to 5 PDFs:
```sh
commonmeta sync --orcid <your-orcid> --dry-run
commonmeta sync --orcid <your-orcid> --limit 25 --pdf --max-pdfs 5
```
The first write asks for permission in a Zotero dialog: choose **Always
Allow**. Each Zotero profile asks once, even after a key was granted in
another.
4. Zotero syncs the new items and PDFs to defter (Settings → Sync → Sync
Now, or the sync button). defter's log then shows `POST
/api/users/<id>/items`, then the file uploads under `/file` and
`/uploads/`; its dashboard counts the items and files.
### Public profile
With `--orcid <your-orcid>` (`DEFTER_ORCID`), defter publishes a profile at
`/<your-orcid>`, without a key: your ORCID record, read by commonmeta and
fetched at most hourly, and your works, which can be searched and narrowed by
year and type, or exported as BibTeX, RIS, CSL-JSON and more. It is available in
English and German.
**Every work in My Publications is shown**, as long as it is at the top level
and not in the trash, with its title, creators, date, abstract, publication,
language, rights and DOI. Its tags, notes and files are not, nor are they exported. The rest of the
library stays private. A work with a PDF attached links to where that PDF was
published, never to the file stored in defter or Zotero; a PDF uploaded from disk
has no such place and is not linked. A work with the manual tag `featured` also shows under
"Featured only".
The dashboard links to the profile and, signed in with a read/write key, can
hide it; the address then answers `404`. Unlike defter's other pages, the
profile may be indexed by search engines.
## Development
```sh
cargo test # unit and API tests
cargo run -- start # http://127.0.0.1:8189, files on local disk
```
Building needs only Rust. Pages are askama templates in `templates/`,
compiled into the binary, so a template change needs a rebuild (`cargo run`
does it). Their stylesheet, `ui/dist/app.css`, is built from `ui/app.css` by
the standalone [Tailwind CLI](https://tailwindcss.com/docs/installation/tailwind-cli)
and committed. To change styling, install it (`brew install tailwindcss`, or
a release binary with `TAILWINDCSS=/path/to/tailwindcss`); the build then
regenerates the stylesheet, and warns when it can't. The script is the
vendored htmx (`ui/vendor/`, see its README for updating) plus `ui/main.js`.
To run against real S3 storage locally, use [RustFS](https://rustfs.com):
```sh
docker run -d --rm --name rustfs -p 9000:9000 \
-e RUSTFS_ACCESS_KEY=defter -e RUSTFS_SECRET_KEY=defter-secret rustfs/rustfs
curl --aws-sigv4 "aws:amz:us-east-1:s3" --user defter:defter-secret \
-X PUT http://127.0.0.1:9000/zotero # create the bucket
DEFTER_S3_BUCKET=zotero DEFTER_S3_ENDPOINT=http://127.0.0.1:9000 \
DEFTER_S3_REGION=us-east-1 DEFTER_S3_ACCESS_KEY_ID=defter \
DEFTER_S3_SECRET_ACCESS_KEY=defter-secret cargo run -- start
DEFTER_KEY=$(cargo run -q -- key) scripts/smoke-s3.sh # file round trip
```
### Layout
| `src/main.rs` | CLI and startup |
| `src/app.rs` | state, router, gzip and logging middleware |
| `src/zotero.rs` | Zotero API handlers |
| `src/auth.rs` | keys, login sessions, expiring tokens |
| `src/store.rs`, `migrations/` | library storage in SQLite |
| `src/query.rs` | item listing parameters |
| `src/db.rs` | connections and migrations |
| `src/storage.rs` | attachment files via `object_store` |
| `src/ui.rs`, `templates/` | web UI pages (askama) |
| `src/profile.rs` | public profile: ORCID record and what the page shows |
| `ui/` | the pages' stylesheet (Tailwind) and script (vendored htmx) |
## License
MIT. Includes code adapted from zhost (MIT), see `NOTICE`.