How to Transfer Books to Xteink X4 (SD, Wi-Fi, App)

To transfer books to the Xteink X4, copy EPUB files onto the microSD card. That works on every firmware. On CrossPoint firmware, send them over Wi-Fi with the browser upload page, the CrossPoint Sync phone app, or the Calibre plugin. The USB-C cable is charge-only and never transfers files.

You plugged in the USB-C cable, dragged an EPUB across, and got a charging icon. No drive mounted. No library entry. There are four ways to put a book on the Xteink X4 and X3, from the SD card every unit ships with to a free phone app.

Why Won’t the Xteink X4 Transfer Books Over USB-C?

The Xteink X4 and X3 will not transfer books over USB-C because the port is charge-only. There is no USB Mass Storage mode, so plugging either device into a computer never mounts a drive you can drop files into.

An open GitHub feature request asks CrossPoint for USB “Target Mode” (MTP or microSD-card passthrough) so Calibre could send books over the cable instead of the network. A CrossPoint maintainer said that is a hardware limit, not a firmware setting. The ESP32-C3 chip inside the X4 and X3 does not support USB gadget mode, so mass-storage or MTP transfer is not coming to either device on CrossPoint. The Microreader firmware does move files over the cable, through a USB serial connection in a browser, not by mounting the X4 as a drive. The stronger ESP32-S3 chip supports gadget mode, so drive-style transfer is plausible on future hardware. It is not a fix to wait for on the X4 or X3 you own today.

The right method depends on firmware. If you are unsure, start with the SD card. It works on every firmware with no setup.

Which Transfer Method Should I Use?

Which transfer method you use on the Xteink X4 depends on firmware. Stock is the SD card only. CrossPoint adds Wi-Fi upload, the phone app, and Calibre.

Match your setup to a method

How Do I Add Books to the Xteink X4 with the SD Card?

You add books to the Xteink X4 with the SD card on every firmware: stock, CrossPoint, Microreader, Papyrix. It is the only path before you flash, and the fastest way to load a big batch.

What you need: the microSD card that came with the device (or any card formatted as FAT32, a SanDisk 256GB Ultra microSD is a common upgrade) and a way to read it on your computer, either a slot in your laptop or a USB card reader. Replacement cards and other owner-tested gear are on the Xteink X3 and X4 cases and accessories list.

Steps:

1. Power down the Xteink. A clean shutdown before you pull the card avoids a half-written library index.
2. Pop out the microSD card. Hold the device face-up in portrait orientation. The slot is on the right edge, near the bottom. It is a spring-loaded push-push slot, so press the card in and it clicks out.
3. Plug the card into your computer. Use a laptop slot or a USB card reader.
4. Copy your EPUB or TXT files onto it. They can go anywhere on the card. A folder called books keeps things tidy, but dropping them in the root works just as well.
5. Eject the card cleanly and put it back in the device.
6. Power on. Your books appear in the library automatically.

The slot sits flush with the case and the card is recessed, so getting a fingernail on it is genuinely fiddly on some units. If you can’t get a grip, a SIM-eject pin or a straightened paperclip gives you the press you need without scratching the case.

Format the card as FAT32. It is the format the X4 and X3 read most reliably across every firmware, including stock. On Windows: right-click the card → Format → File System: FAT32 → Start. On Mac: Disk Utility → select the card → Erase → Format: MS-DOS (FAT). Formatting erases everything on the card, so copy off anything you want to keep first. The one exception: FAT32 maxes out at 32 GB on the Windows formatter, so for a card larger than 32 GB use exFAT instead, but a smaller FAT32 card is the safest default.

If the device does not show your books after reinserting, check three things: the files are EPUB or TXT (not MOBI, KFX, or PDF), the card is FAT32, and the EPUB itself is not malformed. MOBI/KFX files convert for free in Calibre (see the format section), and Calibre’s “Check and fix” function catches bad EPUBs before you load them. If the device instead hangs on an “Indexing” screen after the card goes back in, that’s a known stock-firmware symptom with its own fix list: see Xteink X4 stuck on indexing or books not showing up.

How Do I Upload Books to the Xteink X4 Over Wi-Fi?

You upload books to the Xteink X4 over Wi-Fi on CrossPoint or CrossInk firmware by opening the device file manager in a browser and dragging EPUBs in. This does not work on stock firmware. Microreader is X4-only; if you flashed it, use the SD card.

No extra software is needed on your computer, only a browser. The CrossPoint Sync phone app is a separate send path if you would rather load books from a phone. The device runs a local file server and you drag books into it from any computer or phone on the same network.

What you need: CrossPoint firmware, the device connected to the same Wi-Fi as your computer, and any browser.

Steps:

1. Connect the Xteink to Wi-Fi. On the device, go to Settings → Wi-Fi and join your network.
2. Open the file manager in a browser. In the address bar (the bar where you type URLs, not the search box), type http://crosspoint.local and press Enter. This mDNS hostname reaches the device without you hunting for its IP.
3. Drag your EPUB files into the upload area. The CrossPoint file manager handles the rest.
4. Done. Books appear on the device, no reboot needed.

The crosspoint.local shortcut is reliable on Mac and most phones but flaky on Windows, which often lacks the mDNS resolver. If the page won’t load, fall back to the device IP: the Xteink shows its address (something like 192.168.1.45, varies by network) on the Wi-Fi settings screen, then type that into the address bar instead.

If the computer and the Xteink are not on the same Wi-Fi, enable hotspot mode instead. In CrossPoint go to Settings → Hotspot, then join the Xteink’s Wi-Fi network from your computer. Open a browser to the IP shown on the hotspot screen, typically 192.168.43.1. Same file manager, same drag-and-drop.

Prefer mounting it like a drive? CrossPoint also exposes a WebDAV server. Point a WebDAV client (Finder’s Connect to Server, Windows Map network drive, or an app like RaiDrive) at crosspoint.local (or the device IP) and the Xteink’s storage mounts as a folder you can copy whole batches into. Handy if you’d rather use your file manager than a browser upload box.

This is the everyday method for one-book loads once you are on CrossPoint. CrossInk (a CrossPoint fork) also supports this file server.

How Do I Send Books from Calibre to the Xteink?

You send books from Calibre to the Xteink X4 over Wi-Fi on CrossPoint firmware. A plugin puts the device on Calibre’s device list, so you right-click and send the same way you would to a Kindle. The plugin uses UDP to discover the Xteink on your LAN and a WebSocket to push the file, so once it is set up the device shows up on its own.

What you need: CrossPoint firmware, Calibre installed on your computer, and the CrossPoint Calibre plugin. It lives in its own repo, github.com/crosspoint-reader/calibre-plugins, not the main firmware repo.

Steps:

1. Download the plugin .zip from the calibre-plugins repo.
2. Load it into Calibre. Preferences → Plugins → Load plugin from file → select the .zip (do not unzip it first; Calibre installs directly from the zip), then restart Calibre.
3. Wake the Xteink on the same network. Once it is on and connected, it appears in Calibre’s device list on its own.
4. Send a book. Right-click any title → Send to device.

Calibre converts to your preferred output format automatically during the send, so no pre-converting is needed. It also keeps your whole library’s metadata, covers, and series in one place.

On connect the plugin lists every EPUB already on the Xteink, including ones you loaded via SD card or the browser upload, and matches each one to your library by filename. Calibre’s “on device” indicator stays accurate no matter how a book got there. You can delete a book from Calibre and have it removed from the Xteink too.

Set the output format to EPUB, not Kepub. If you are migrating from a Kobo, Calibre may have your library stored as Kobo’s .kepub variant. Kepub files do not sync with CrossPoint (or KOReader), so set Calibre’s output to plain EPUB before you send. EPUB is the common denominator every Xteink firmware reads.

Troubleshooting the plugin:

• Device never appears in Calibre. Confirm the computer and Xteink are on the same Wi-Fi network (not a guest network or a band split that isolates clients), the device screen is awake, and Calibre was fully restarted after install. UDP discovery is blocked by some VPNs and router “client isolation,” so toggle those off to test.
• “Send to device” fails or hangs. A firewall prompt for Calibre may be sitting unanswered; allow Calibre through your OS firewall, then re-wake the device and retry.

How Do I Send Books from My Phone? (CrossPoint Sync App)

You send books from your phone to the Xteink X4 with the free CrossPoint Sync app on CrossPoint firmware. The open-source iOS and Android companion from crosspointsync.com pushes EPUBs over Wi-Fi with no card reader and no IP typing. It also clips web articles into EPUBs.

What you need: CrossPoint firmware, the app on your phone, and the phone and Xteink on the same Wi-Fi.

Steps:

1. Install CrossPoint Sync from crosspointsync.com.
2. Put your phone and the Xteink on the same network.
3. Open the app. It discovers the device the same way the Calibre plugin does.
4. Share an EPUB or a web page to the app. The file lands in your library.

Xteink’s own XT-Cloud book-sync service and the official Companion App also do wireless transfer for the X3 and X4. You need a free XT-Cloud account. It is the vendor-supported alternative to CrossPoint Sync. There is no public API, so it is app-only.

Can I Sideload Books on the Xteink X3 With NFC?

The Xteink X3 can open its CrossPoint upload page with one iPhone NFC tap. The X4 has no NFC. An r/XTEINK owner built the Shortcut. Setup, the iCloud link, and the Actions app requirement are on the X3 NFC iPhone hotspot shortcut post.

What File Format Does the Xteink X4 Need?

The Xteink X4 needs EPUB or TXT on every firmware. CrossPoint and CrossInk also read FB2, Markdown, and some manga formats. If you are migrating from Kobo, send plain EPUB, not Kobo’s .kepub. Kepub files don’t sync with CrossPoint or KOReader.

If you are coming from Kindle, your books are likely MOBI or KFX files with DRM (copy protection). Neither format works on the Xteink, and DRM-locked files cannot be converted; they are tied to your Kindle account. You need DRM-free EPUBs. Good sources: Project Gutenberg (classics, free), Standard Ebooks (cleaned-up public domain, free), Smashwords, Humble Bundle ebook bundles, or direct from authors.

Regular Libby and OverDrive loans will not open on the Xteink X4. See Can you use Libby on Xteink?.

If an EPUB crashes the reader or shows broken formatting, run it through CrossPoint’s built-in EPUB Optimizer, which rewrites a problem book into something the reader handles cleanly. Re-converting in Calibre is the other reliable fix.

Reading fanfiction or web articles? An AO3 fic, a saved blog post, or a longread you want off your phone converts to EPUB. The CrossPoint Sync app clips a web page to EPUB for you. On the desktop, Calibre’s Add books → From web and the AO3 “Download → EPUB” button do the same. Once it’s an EPUB, every method above applies.

Quick Troubleshooting

Most failed transfers on the Xteink X4 are a wrong format, a card that is not FAT32, or a Windows box that cannot resolve crosspoint.local.

Common Transfer Questions

Why doesn't USB-C file transfer work on the Xteink X4?

By design. The USB-C port on the Xteink X4 and X3 is charge-only: the ESP32-C3 chip inside doesn't support USB gadget mode, so there is no Mass Storage or MTP and the cable never mounts a disk. Transfer files with the SD card or, on CrossPoint firmware, one of the Wi-Fi methods instead.

Do the same methods add books to the Xteink X3 and X4?

Yes. The Xteink X3 and X4 load books the same four ways: microSD card on any firmware, plus browser upload, the CrossPoint Sync app, and the Calibre plugin on CrossPoint. Both devices have charge-only USB-C. The one X3 extra is NFC, which powers the one-tap iPhone hotspot shortcut above; the X4 has no NFC. Still deciding between the two devices? See the Xteink X3 vs X4 comparison.

Can Calibre connect to the Xteink over USB?

No. Calibre reaches the Xteink X4 and X3 only wirelessly, through the CrossPoint Calibre plugin: it discovers the device over your Wi-Fi network and pushes books with no cable involved. A USB connection can never work because the hardware has no USB file-transfer mode, so if Calibre doesn't list the device, check the network, not the cable.

How do I download books onto the Xteink X4?

The Xteink X4 does not download books from a store. When people say download, they mean getting a file from a phone or computer onto the device. Grab the EPUB wherever you buy or borrow it, then load it with the SD card (works on every firmware) or one of the Wi-Fi methods above (CrossPoint).

Can I send Kindle books to the Xteink X4?

Only DRM-free ones. Kindle books are usually MOBI or KFX files with DRM tied to your Amazon account, and DRM-locked files cannot be converted for the Xteink. A DRM-free MOBI converts to EPUB for free in Calibre. Start with DRM-free EPUBs and test three to five books before assuming your whole shelf will move.

Does the Xteink X4 read MOBI files? What formats are supported?

No MOBI. The Xteink X4's supported file formats are EPUB and TXT on every firmware; CrossPoint and CrossInk add FB2, Markdown, and some manga formats. Convert a DRM-free MOBI to EPUB for free in Calibre, and skip Kobo's `.kepub`, which won't sync with CrossPoint.

Why does my Kobo book not sync?

It is probably a `.kepub` file. Kepub does not sync with CrossPoint or KOReader, so set Calibre's output format to plain EPUB and re-send. EPUB is the common denominator every Xteink firmware reads.

What if `crosspoint.local` won't load?

That hostname relies on mDNS, which Windows often lacks. Read the device's IP from its Wi-Fi settings screen and type that into the browser address bar instead. The IP fallback is not optional on Windows.

What Should I Do Next?

Put one EPUB on the Xteink X4 with the method that matches your firmware.

• On stock firmware: an SD card formatted FAT32 is the only route, and the fastest for big batches. If stock is misbehaving instead of transferring, start with Xteink X4 stuck on indexing, SD card error, and ghosting fixes.
• On CrossPoint: browser or WebDAV upload, the CrossPoint Sync phone app, or the Calibre plugin, all over Wi-Fi, no card reader.
• Whatever the method: send plain EPUB, not Kobo .kepub, and use the EPUB Optimizer if a book misbehaves.

Still on stock and want Wi-Fi send? Flash CrossPoint first, then come back and send the file.

If the bundled card keeps failing (overheat, “SD card error”, books vanishing after a format), swap it for a name-brand card before you blame the firmware.

Get a SanDisk 32GB Ultra microSD  or see every owner-tested card and reader on the accessories list.

Related Guides

• Flash CrossPoint on Xteink X3 and X4: how to install CrossPoint if you haven’t yet, including the locked-device path
• First-Week Setup Checklist: the broader first-week picture, covering inspection, firmware safety, carry setup
• Is My Xteink Locked?: if your AliExpress unit has USB flashing disabled, what to do