How to Set Up an OPDS Server on iPhone & iPad (2026 Guide)

Quick answer: To set up an OPDS server on iPhone or iPad, install an OPDS-capable reader app, open its Library or Catalogs section, add a new catalog, paste the server's full OPDS URL (for example http://192.168.1.10:8080/opds for a Calibre Content Server, not the bare IP address), give it a name, and add a username and password only if the server asks for one. Save it, and the app lists every book on that server, ready to download and read offline. The single most common mistake is leaving off the /opds path or the port number.

OPDS sounds like something you need a home-server background to touch, and it turns out to take about two minutes once you know the two things that trip everyone up: the exact path a server expects, and how each server handles logins. This guide walks through adding your first catalog end to end, the precise steps inside the app, the URL patterns for every common server, a short list of public catalogs whose URLs I verified by hand while writing this, and a real troubleshooting checklist for the moment nothing appears.

A note from me: I am Petr Jahoda, and I make justRead. I set up every one of the OPDS connections described here first-hand, on real servers and a real iPhone, rather than paraphrasing a spec. The gotchas below are the ones I actually hit.

This guide was fully rewritten and expanded in July 2026, with every public catalog URL re-tested the day it was published so you are not sent to a dead feed.

What OPDS actually is

OPDS, the Open Publication Distribution System, is a simple standard that lets a reading app browse and download books from a server. The cleanest way to picture it: OPDS is RSS for books. An RSS reader points at one feed address and shows you every new article from that source. An OPDS reader points at one catalog URL and shows you every book a server offers, with covers, authors, descriptions, and download links. You tap a book, it downloads to your device, and you read it offline.

Because it is an open standard rather than one company's app, the same reader can connect to wildly different sources through the same mechanism: a public-domain library like Project Gutenberg, a home media server, and your own Calibre collection all speak the same language. Nothing is locked to a store or an account.

There are two versions you will run into:

• OPDS 1.2 is the version almost everything speaks today. It is built on Atom, the XML feed format, so a catalog is essentially an XML document listing books and sub-sections. When someone hands you an OPDS URL in 2026, it is almost always 1.2.
• OPDS 2.0 is a newer, JSON-based rewrite of the same idea. It is cleaner for developers and is starting to appear (Komga, for instance, serves both), but adoption is still early. You do not need to choose. A good reader negotiates the version for you, and 1.2 is what you will use in practice.

What you need before you start

Connecting to any OPDS catalog needs only two pieces of information, and often just the first:

1. The catalog URL. This is the OPDS endpoint, and it usually ends in /opds or a similar path. For a public catalog, the project publishes it on its website. For your own server, it is the server's address plus the OPDS path that specific software uses (this is where most setups fail, and there is a full section on it below).
2. A username and password, only if the server requires one. Public catalogs are typically open. Private servers, like your own Calibre or Komga, can require a login. If so, you enter it once and the app remembers it.

That is the whole list. No third-party account, no sync service in the middle, no transferring files by hand over a cable.

Step 1: Install an OPDS reader

iOS and iPadOS do not browse OPDS catalogs on their own, so you need a reader app that supports the standard. justRead is an EPUB and PDF reader for iPhone and iPad with OPDS built in: it ships with Project Gutenberg and the Internet Archive as built-in catalogs, lets you add your own servers, and handles server-side search, pagination, and browsing by category so even huge catalogs stay usable. Whichever app you pick, the feature you are looking for is an OPDS or Catalogs section inside its library or settings. If you want the fuller feature rundown before committing, the OPDS reader overview covers what the app supports.

One honest limit worth stating up front: justRead reads EPUB and PDF files. OPDS catalogs that only offer other formats (comic archives, MOBI, and so on) will still browse, but you will only be able to download the EPUB and PDF editions.

Step 2: Add your first catalog, step by step

The fastest way to see OPDS working is a free public catalog, and in justRead the very fastest is one that needs no typing at all.

The no-typing route (built in). justRead ships with Project Gutenberg and the Internet Archive as built-in catalogs. Open the Library, open the catalogs area, and they are already there. Tap Project Gutenberg and you are browsing 70,000+ public-domain books immediately, with no URL to paste. This is the real v3.x feature, and it is the shortest possible path to a downloaded book. Use it once just to confirm the whole flow works before you add anything custom.

The manual route (any catalog). To add a catalog by URL, the flow is the same in most readers, and in justRead specifically:

1. Open the Library.
2. Choose add OPDS catalog (the option to add a new server or catalog).
3. Paste the catalog URL into the address field. Paste it, do not retype it, so you cannot introduce a typo in the path or port.
4. Name it something you will recognize later, like "Home Calibre" or "Gutenberg."
5. If the server requires a login, enter the username and password. Leave them blank if it does not.
6. Save.

The catalog now appears in your list. Tap it to browse. Larger catalogs open into sections you can drill through, so you can browse by category (by subject, author, most popular, recently added, and so on) rather than scrolling one giant list. Use server-side search to query the server directly for a title or author instead of downloading everything first, and pagination keeps long results loading in manageable chunks. Tap any book to download it; it lands in your library and is yours to read offline.

That six-step flow is the entire skill. Everything else in this guide is about getting one specific value right: the URL in step 3.

The /opds path gotcha, in depth

If you take one thing away, take this: the OPDS URL is almost never just the server's address. The bare IP or hostname points at the server's human web page, not its machine-readable OPDS feed. Point a reader at http://192.168.1.10:8080 and you will get an error or a blank catalog; point it at http://192.168.1.10:8080/opds and your library appears. Two details do the damage, the path and the port, and each server handles them differently.

• Calibre Content Server serves OPDS at /opds on port 8080 by default: http://<ip>:8080/opds. Miss the :8080 and the connection dies before it starts. Miss the /opds and you hit the web reader instead of the feed.
• Komga serves its OPDS 1.2 feed at a deeper path: http://<host>:25600/opds/v1.2/catalog. The port is 25600 by default, and the catalog lives several segments in, not at a bare /opds.
• Kavita does something different again: instead of a username and password, it bakes an API key straight into the URL: http://<host>:5000/api/opds/<your-api-key>. There is no separate password to type, because the key in the URL is the credential. Copy the whole pre-built URL from Kavita's settings and leave the login fields blank.

The pattern is: get the port right, get the path right, and check whether the credential lives in the URL or in the login fields. When a connection fails, it is one of those three nine times out of ten.

Step 3: Connect a Calibre Content Server

The most popular private catalog is your own Calibre library. Calibre, the free desktop ebook manager, can publish your whole collection over OPDS in a couple of clicks:

1. On your computer, open Calibre and click Connect/share in the toolbar.
2. Choose Start Content Server.
3. Find your computer's local IP address (something like 192.168.1.10). The OPDS endpoint is then http://192.168.1.10:8080/opds, where 8080 is Calibre's default port.

On your iPhone or iPad, add that URL as a new OPDS catalog with the six steps above. Two things make justRead easier here specifically: it can discover a Calibre Content Server on the same Wi-Fi automatically, so you may not have to find and type the IP at all, and it supports HTTP Digest authentication, which is the login scheme Calibre uses when you turn on its "Require username and password" option.

A few realities of the Content Server worth knowing: Calibre has to stay open and running on the computer for the catalog to work, both devices must be on the same network unless you set up remote access, and if the computer's IP address changes (which home routers do on their own), the catalog URL changes with it. Reserving a static IP in your router, or using the computer's .local hostname, avoids the "worked yesterday, broken today" problem.

This OPDS route is the quickest way to simply read your Calibre books on iOS. If you want the server side done properly, port unblocked, a login added, reachable from outside the house, multiple libraries handled, the Calibre Content Server guide covers only that. And if you want reading progress and ratings to sync back to your computer rather than just one-way browsing, the Calibre library sync workflow adds two-way sync on top.

Self-hosted server URL patterns

If you run a home server, the same six-step flow applies, with each project's own OPDS endpoint. These are the patterns to slot your host and port into:

Notes on the table: the ports shown are each project's common defaults, but any of them can be changed at install time, so confirm yours in the server's own settings if a connection fails. calibre-web's default is often 8083 but depends entirely on how you deployed it (a reverse proxy may drop the port to a plain hostname). COPS has shifted its entry point across versions, so if feed.php does not resolve, check your COPS admin page for the exact OPDS link rather than guessing. Komga also offers an OPDS 2.0 feed at /opds/v2, but the 1.2 catalog path above is the compatible one to start with.

justRead supports custom OPDS servers including Calibre OPDS, calibre-web, Kavita, Komga, and COPS, with per-server filtering and pagination so large catalogs stay manageable. Add the server as a new catalog, enter credentials if the server uses them (remember Kavita's key-in-URL exception), and your shelves appear on your iPhone.

A starter list of public OPDS catalogs

You do not need your own server to use OPDS. Below are public catalogs I re-tested the day this guide was published. I have only listed URLs that actually returned a live OPDS feed, and I have been explicit about the one that is gated, rather than sending you to a link that quietly fails.

• Project Gutenberg (verified live, no login): https://www.gutenberg.org/ebooks.opds/. More than 70,000 public-domain books, fully open, and legal to download. This is the gold-standard first catalog. In justRead it is built in, so you do not even need to paste this URL; it is here for other apps and for reference.
• Unglue.it (verified live, no login): https://unglue.it/api/opds/. A catalog of Creative Commons-licensed and "unglued" ebooks that the site has made free to everyone. Smaller and more eclectic than Gutenberg, and completely open.
• Standard Ebooks (real feed, but gated): the project produces beautifully typeset public-domain ebooks, and it does publish an OPDS feed at https://standardebooks.org/feeds/opds. As of this rewrite, the full feed is not open to the public: it is reserved for Patrons Circle members (a small donation), ebook contributors, and sponsors, and it will temporarily block the IP of anything that scrapes it. If you support the project, patrons authenticate by entering their account email address and leaving the password field blank. If you do not, treat Standard Ebooks as a browse-and-download-from-the-website source rather than a plug-in OPDS URL, and check their site for current access terms before adding it.

I deliberately kept this list short and only to catalogs I could confirm. Several catalogs that show up on older lists (Feedbooks, which shut down in 2024, and a few others) are dead or now block automated access, so I have left them out. For a broader, continuously vetted roundup, including academic and lending sources and the dead feeds to avoid, see the best free OPDS catalogs for 2026. That post owns the "where to point it" question; this one owns "how to point it."

HTTP, HTTPS, certificates, and logins

Local home servers usually run over plain HTTP on your own network, which is fine because the traffic never leaves your house. You will type http:// (not https://) for a Calibre Content Server on your Wi-Fi, and that is expected.

The moment you want to reach a catalog from outside your home, HTTPS matters, and iOS is strict about it:

• iOS rejects untrusted certificates. If your server uses a self-signed certificate, iOS will refuse the connection rather than show a "proceed anyway" button in a reader. The reliable fix is a real certificate: put the server behind a domain name and issue a free certificate (for example with Let's Encrypt), typically via a reverse proxy. Then iOS trusts it like any normal website. Manually installing and trusting a self-signed certificate in iOS Settings is possible but fiddly, and a proper certificate is less trouble in the long run.
• Basic vs Digest authentication. OPDS servers protect themselves with one of two HTTP login schemes. Basic auth sends your username and password with each request (safe over HTTPS, exposed over plain HTTP), while Digest auth is a challenge-response scheme that never sends the raw password. Calibre's Content Server uses Digest, which justRead supports. For any server, use exactly the username and password you set on the server side; a single wrong character reads to the app as "access denied," not "wrong password," which is why login typos masquerade as connection failures.

Nothing shows up? A full troubleshooting checklist

When a catalog will not load, work down this list in order. Each item is a real cause I have hit:

1. Wrong path. You used the bare address instead of the full OPDS path. Add /opds (Calibre), /opds/v1.2/catalog (Komga), or whatever your server documents. This is the number-one cause.
2. Missing port. You dropped the :8080 (Calibre), :25600 (Komga), :5000 (Kavita), or :8083 (calibre-web). Without the port, the request goes nowhere.
3. Same network? For a home server, phone and server must be on the same Wi-Fi. Phones love to fall back to cellular; if you are on 5G and the server is a LAN-only 192.168.x.x address, it is simply unreachable. Confirm Wi-Fi is on and joined to the right network.
4. LAN-only IP from outside. A 192.168.x.x or 10.x.x.x address only works inside your home. It will never resolve from a coffee shop. Reaching it remotely needs a VPN back home, or a proper domain and reverse proxy (see the Content Server guide).
5. Firewall blocking the port. The single most common Calibre failure: the server is running, the URL is correct, but the computer's firewall silently blocks incoming connections on 8080. Allow the port (or the Calibre app) through the firewall on the machine running the server.
6. Server not actually running. Calibre must stay open with the Content Server started; a self-hosted container must be up. If Calibre is closed or the container stopped, the catalog is gone. Load the same URL in a desktop browser on the same network: if the browser cannot reach it either, the problem is the server, not the app.
7. Auth typo. A wrong username or password reads as a failed connection. Re-enter credentials carefully, watching for autocapitalization on the first letter and a trailing space from paste.
8. HTTPS certificate rejected. A remote server on a self-signed certificate is refused by iOS. Move to a trusted certificate as described above.
9. The address changed. It worked yesterday and not today because the router handed the computer a new IP. Reserve a static IP, or use the .local hostname.

The fastest single diagnostic is step 6's browser test: open the exact OPDS URL in Safari or a desktop browser on the same network. If you see raw XML, the server and URL are good and the problem is in the app or its credentials. If the browser also fails, the problem is the server, the port, or the network, and you have just cut the search in half.

Where OPDS fits in your reading setup

OPDS turns an iPhone or iPad into a front end for any library you can point it at, public or private, without copying files around by hand. Once a catalog is set up, adding a new book is two taps. Most people end up with a small mix: a built-in public catalog for classics, and their own Calibre or self-hosted server for everything they actually collect.

• New to ebooks on iOS in general? Start with how to read EPUB on iPhone and iPad.
• Want the full picture of what an OPDS reader can do? See the OPDS reader overview.
• Deciding which public catalogs to add? Use the best free OPDS catalogs for 2026.
• Running your own Calibre? The Calibre Content Server guide covers the server end, and Calibre sync adds two-way progress and rating sync.

justRead includes a 14-day free trial, so you can set up your first catalog and confirm the whole flow works before deciding. Download justRead on the App Store and add your first OPDS catalog today.

Frequently asked questions

What is an OPDS catalog?
An OPDS catalog is a feed that lets a reading app browse and download books from a server, much like an RSS reader subscribes to a news feed. You point your app at the catalog URL and it lists every book the server offers, with covers and descriptions, ready to download and read offline.

What is the correct OPDS URL for a Calibre Content Server?
It is your computer's local IP, plus Calibre's port, plus the /opds path: http://192.168.1.10:8080/opds. The two mistakes that break it are using the bare IP with no /opds, and forgetting the :8080 port.

Do I need Calibre to use OPDS on iPhone?
No. You can connect to public catalogs like Project Gutenberg with no server of your own, and in justRead, Gutenberg and the Internet Archive are built in with nothing to type. Calibre's Content Server is just one popular OPDS source, useful if you already keep your library in Calibre on a computer.

Why won't my OPDS server connect on iOS?
The usual causes, in order, are: the wrong path (missing /opds), a missing port number, the phone and server being on different networks, a firewall blocking the port, a login typo, or a self-signed HTTPS certificate iOS refuses to trust. Load the exact URL in a desktop browser on the same network to tell whether the problem is the server or the app.

Why doesn't Kavita ask for a username and password?
Kavita puts an API key directly in the OPDS URL (http://<host>:5000/api/opds/<your-api-key>), so the key is the credential. Copy the full URL from Kavita's settings, paste it as the catalog address, and leave the username and password fields blank.

What is the difference between OPDS 1.2 and OPDS 2.0?
OPDS 1.2 is the older, XML-based version built on Atom, and it is what almost every server and reader speaks today. OPDS 2.0 is a newer JSON-based version that is cleaner for developers and starting to appear (Komga serves both), but adoption is early. A good reader handles whichever a server offers, so you rarely choose.

Does OPDS work over HTTPS and self-signed certificates on iPhone?
It works over HTTPS with a trusted certificate. iOS rejects self-signed or otherwise untrusted certificates outright, so for remote access put the server behind a real domain and a free certificate (for example Let's Encrypt) rather than a self-signed one. Plain HTTP is fine for a server on your own Wi-Fi.

Can I reach my home OPDS server from outside the house?
Not with a 192.168.x.x LAN address, which only resolves inside your home. To reach it remotely, either connect back with a VPN, or expose the server through a domain name and a reverse proxy with a trusted certificate. The Calibre Content Server guide walks through the safe remote-access setup.

How many books can OPDS handle on a phone?
Very large libraries are fine, because OPDS is browse-first: the app only downloads a book when you tap it, not the whole catalog. justRead uses server-side search and pagination so a catalog of tens of thousands of titles loads in chunks and stays responsive, and you can browse by category instead of scrolling everything.

Which servers does justRead support over OPDS?
justRead connects to standard OPDS servers including Calibre's Content Server, calibre-web, Komga, Kavita, and COPS, with per-server filtering, server-side search, pagination, and browse-by-category. It also finds a Calibre Content Server on the same Wi-Fi automatically and supports Calibre's HTTP Digest login. Downloads are EPUB and PDF.

What can I download over OPDS in justRead?
EPUB and PDF files. You can browse catalogs that also list other formats, but justRead will download and open the EPUB and PDF editions.