Calibre Content Server on iPhone & iPad (OPDS Guide)

Quick answer: Open Calibre on your computer, click Connect/share, and choose Start Content Server. Your library is then available at http://<your-computer-ip>:8080/opds. Add that URL as an OPDS catalog in a reader app on your iPhone or iPad, enter a login only if you required one, and your whole Calibre library appears, ready to download and read.

Calibre is the best free way to organize an ebook library on a computer, but it does not have an iPhone app. Its Content Server closes that gap: it serves your entire collection over your network so you can read it on iOS without copying a single file by hand. This guide covers the full setup, how to reach it from your phone, how to secure it, and when a deeper two-way sync is the better choice.

What the Calibre Content Server does

The Content Server is a small web server built into Calibre. When you start it, Calibre publishes your library in two ways at once: a browsable web page, and an OPDS feed that reading apps understand. The OPDS feed is what matters here, because it lets an app on your iPhone list every book, with covers and metadata, and download anything on demand. Both EPUB and PDF files in your library are served.

Step 1: Start the Content Server in Calibre

1. Open Calibre on your computer.
2. Click Connect/share in the toolbar.
3. Choose Start Content Server.
4. If your operating system or antivirus asks, allow Calibre through the firewall.

The server is now running. It stays up only while Calibre is open, so this is a "reading at home" feature rather than an always-on service, unless you set up remote access (below).

Step 2: Find your OPDS address

The OPDS endpoint is your computer's local IP address, the default port 8080, and the path /opds:

http://192.168.1.10:8080/opds

Replace 192.168.1.10 with your own machine's address. On Windows you can find it with ipconfig; on macOS it is in System Settings under your Wi-Fi connection. If you changed Calibre's port in Preferences, use that number instead of 8080.

Step 3: Connect from your iPhone or iPad

In an OPDS-capable reader, open the OPDS or Catalogs section, add a new catalog, and paste the URL from step 2. If you have not set up OPDS before, the step-by-step OPDS guide walks through it.

justRead makes this step easier in two ways. It can discover a Calibre Content Server on the same Wi-Fi automatically, so you often do not have to type the address at all, and it supports HTTP Digest authentication for servers that require a login. Once connected, you can browse your library, search it, and download books to read offline.

Both devices need to be on the same Wi-Fi network for the local address to work. If the catalog loads but shows nothing, double-check that you are pointing at /opds and not the plain web address.

Securing and accessing it remotely

For home use on your own network, a login is optional. The moment you want to reach your library from outside the house, security matters:

• Add a password. In Calibre, go to Preferences, then Sharing over the net, and enable "Require username and password." Apps that have separate credential fields will prompt you; for apps that do not, you can embed the login in the URL as http://user:pass@192.168.1.10:8080/opds.
• Use HTTPS for remote access. iOS will not connect to a remote server over plain HTTP, and it rejects self-signed certificates unless you install and explicitly trust them. The reliable path is a real certificate, usually through a domain name and a reverse proxy, or simply a VPN back into your home network so the connection stays local.
• Avoid blindly forwarding the port. Opening port 8080 to the internet without HTTPS and a password exposes your library to anyone who scans for it.

Content Server access vs full two-way sync

OPDS over the Content Server is read-only: you browse and download, and that is it. That is perfect when you just want your books on your phone. If you want your reading life to stay in sync between devices, justRead's deeper Calibre sync builds on the same Content Server connection and adds two-way sync. It writes your reading progress, ratings, want-to-read flags, finished dates, and reading statistics back to Calibre, and it pulls your star ratings and custom columns in. Status badges (New, Changed, Synced) and a "Select New & Changed" option make repeat syncs quick, and a post-sync log shows what happened per book.

In short: use plain OPDS when you want to read, and two-way Calibre sync when you want your computer and phone to agree on where you are in every book.

Troubleshooting

• Nothing loads. Confirm Calibre is open, the Content Server is started, both devices share a network, and the IP and port are correct.
• It connects but then breaks a few days later. Your computer's IP likely changed on DHCP. Reserve a static IP in your router, or use the machine's .local hostname.
• It asks for a login. You enabled authentication in Calibre. Enter those credentials, or turn the requirement off for home use.
• Remote access fails. Plain HTTP from outside your network is blocked by iOS. Set up HTTPS with a trusted certificate, or use a VPN.

Read your whole library, no file shuffling

The Content Server is the simplest way to put a large Calibre library on your iPhone or iPad without duplicating files or fighting with cables. Set it up once, and every book you have organized on your computer is a tap away. For the broader picture of catalogs and servers, see the OPDS reader overview, and for keeping progress in sync across devices, the Calibre sync workflow.

Download justRead on the App Store and connect your Calibre Content Server in minutes.