Flat / EPUB hosting
EPUB hosting: share an ebook readers can open online.
Publish an EPUB from your browser or the CLI. Share a link to the browser reader, with the original ebook available to download.
Checking your upload limits... · Public · Limits
Drop your EPUB files here
or choose them from your device.
Select EPUB filesWhat readers see at your EPUB link
A single supported EPUB opens in Flat's ebook reader. Readers can move through the book and adjust text size without installing an ebook app or creating a Flat account.
Upload several ebooks together and readers can choose a title from the file explorer. The original EPUB files remain available to download for use in a compatible reading app.
An exact file path, such as /guide.epub, serves the original EPUB. Share the main upload link when you want someone to read it in the browser.
How to publish an EPUB and share a link
Prepare your EPUB
Export a finished, unencrypted EPUB from your writing or ebook tool. Keep the book's images, styles, and fonts inside the EPUB. The browser reader does not fetch external assets or run scripts.
Upload the .epub file itself. You do not need to unzip it. Books up to 5 MiB can use the browser preview, subject to the expanded-content limits below.
Upload in your browser
Drop one or more EPUB files into the uploader above, or select them from your device. Enter your email if signed out, then choose "Publish ebooks".
Each file needs a unique name. Selected books publish together at the top level. The browser uploader does not accept folders or extract a ZIP containing several books.
Deploy with the CLI
Install Node.js 20 or newer, then run this command from the directory containing your ebook:
npx -y @getflat/cli deploy ./guide.epubReplace ./guide.epub with your file path. To publish several books, pass their folder path instead. The CLI preserves relative file paths and prints the published URL.
Open and share the URL
Check chapter navigation, text, and images in the published reader. Open the link on the devices your readers use before distributing it.
Signed-out uploads expire after 1 hour by default. Sign in before expiry to keep them online, or sign in before publishing for no default expiry.
What you can publish with EPUB hosting
Reader copies and excerpts
Send a finished ebook or sample to early readers. Collect feedback through your usual email or review tool. Flat hosts the file and provides the reader.
Guides and manuals
Share an EPUB edition of your guide so readers can adjust the text size or download it to a compatible ebook app.
Course reading
Publish reading materials as individual EPUB files in one upload. Students can choose a book from the explorer and keep an original copy for later reading.
Keep a version, or keep an address.
Share this version
Every upload gets its own link. Publishing revised files creates a new link and leaves the earlier version unchanged. Use the version link when someone needs to review a specific upload.
Update files at one address
Use a named onflat.page address or your own domain. Sign in, then publish with the CLI using --domain. Publish revised files with the same domain to point that address to the new upload.
Named addresses are included on Free. Adding your own domain requires a paid plan. The browser uploader does not set up or repoint these addresses.
EPUB hosting questions
Is hosting free, and what are the limits?
Yes. Signed-in Free includes 5 MiB per upload, 1 GiB of storage, and 5 GiB of monthly transfer, with no default expiry. The per-upload limit covers all files in that upload. Paid plans raise these limits.
Do readers need a Flat account?
No. Public links open without a Flat account. Anyone with the link can open the uploaded files. Password-protected links also require the visitor password.
Can I password-protect my upload?
Yes. Password protection is available on every plan. Add --password YOUR_PASSWORD to your CLI deploy command. It protects access to the upload and its files, but does not prevent someone with access from saving a copy. The browser uploader creates public uploads.
Can I replace files without changing the link?
A version link always refers to its original upload. For same-address updates, use a named address or your own domain. Publish revised files with the same --domain value in the CLI to point that address to the new upload.
What happens when an upload expires?
Flat stops serving it. An expired upload cannot be recovered. Signed-out uploads expire after 1 hour by default. For browser uploads, use the sign-in link shown after publishing. For CLI uploads, run npx -y @getflat/cli login. Complete sign-in before expiry to keep the upload online. If you chose a shorter expiry in the CLI, that deadline stays in place.
What are the EPUB reader limits?
The browser preview accepts EPUB files up to 5 MiB, with at most 100 MB of expanded content and 10,000 archive entries. Loading has a 10-second limit. Larger paid upload allowances do not raise these preview limits. Unsupported or over-limit books remain available as original downloads.
Can I upload a DRM-protected ebook?
The browser reader requires an unencrypted EPUB. It cannot unlock DRM-protected books. Password protection on a Flat upload controls access to the hosted file; it does not add ebook DRM or prevent downloads.
Do interactive EPUB features work?
The reader disables scripts, forms, external network access, and top-level navigation. Include assets inside the EPUB and check the result before sharing. An ebook that depends on those interactive features will not behave like it does in its original app.
Does Flat convert Kindle or PDF files into EPUB?
No. Flat reads an existing EPUB and keeps its original format. Export an EPUB with your own tool first. A PDF uses Flat's separate PDF viewer.
Can I embed the ebook reader in my website?
Flat's generated reader cannot be embedded in an iframe and keeps Flat branding on every plan. Link to it, or use the original EPUB URL with your own compatible reader.
Give readers a link to your ebook.
Publish your EPUB, check the chapters and images, and share the URL.
Publish ebooksFree to start · View pricing
Sharing a fixed-layout document? See PDF hosting.