Formats and limits
Last updated 10 October 2026
Finepress turns PDFs, DRM-free Kindle books and plain-text files into EPUB books, and opens EPUBs as they are. All of it happens in your browser. This page lists what it reads, what it writes, and where it falls short.
Which files can Finepress open?
PDF, EPUB, DRM-free Kindle books (MOBI, AZW, AZW3) and TXT. Each becomes an EPUB on your shelf.
| File | What happens | Notes |
|---|---|---|
| Converted to EPUB | Text PDFs and scans. Scanned pages are read with OCR. A PDF locked with a password does not convert. | |
| EPUB | Opened as it is | An EPUB locked with DRM by Adobe, Kobo, Apple or Readium LCP is refused. An EPUB whose only protection is font obfuscation opens. |
| Kindle MOBI, AZW, AZW3 | Converted to EPUB | DRM-free files only. A book locked to an Amazon account is refused. KFX and Topaz are not supported. Convert MOBI and AZW3 to EPUB has the details. |
| TXT | Converted to EPUB | UTF-8, UTF-16, GB18030, Big5, Shift_JIS and EUC-KR are detected. Chapters are found from headings such as "Chapter 3" or "第三章". |
| A link to a web article | Saved as an EPUB | Public article pages only. The address goes to Finepress's server, which fetches the page and its images. Sign-in pages, paywalls and interactive apps are not supported. |
Finepress refuses a locked book. It does not remove copy protection.
What does Finepress produce?
A reflowable EPUB 3 file: the text flows to fit the screen and the font size you choose. Open the book's details on the shelf and press Download EPUB to save it.
- It does not write fixed-layout EPUB, Kobo KEPUB, MOBI or AZW3.
- Marks and notes export as Markdown or JSON.
- Download backup saves the whole library, with marks, places and settings, as one ZIP file.
- To read the EPUB on an e-reader, see Read a PDF on your Kindle and Read a PDF on a Kobo.
When does OCR run, and in which languages?
OCR runs only on pages that have almost no text and are mostly covered by an image, and it reads printed English and simplified Chinese.
A PDF that already carries text on most pages uses that text and gets no OCR. The OCR engine and its language data, about 10.6 MB, download the first time a scanned page needs them and then stay cached. Convert a scanned PDF to EPUB covers the details.
What converts well, and what needs cleanup?
Novels, essays, chaptered non-fiction and one-column reports convert best. Tables, equations, magazines and complex layouts can need cleanup.
- Done for you: running headers, footers and page numbers are removed, columns are read in order, words split across lines are joined, and paragraphs, headings, chapters and figures are rebuilt.
- Tables are flattened into text.
- Equations are kept as text in reading order, not as mathematics, so expect them to be wrong.
- Complex layouts, such as magazine pages, can come out in the wrong order.
- OCR text can have wrong words, more so on a poor scan.
Finepress sets no page or file size limit of its own. A very large PDF is limited by the memory of your device. One 990-page, 23 MB PDF has converted in about four minutes.
What is not supported?
- Books locked with DRM, and PDFs locked with a password
- KFX and Topaz Kindle files
- OCR in languages other than English and simplified Chinese, and handwriting
- Output formats other than EPUB
Which browsers does Finepress work in?
Current versions of Chrome, Edge, Firefox and Safari, on a computer, tablet or phone. The code Finepress ships is checked against Chrome 119, Firefox 121 and Safari 17.4 as the oldest versions. Layouts work down to a screen 320 pixels wide.
After the first visit, the shelf and the reader work offline, and Finepress can be installed as an app.
How much can I store?
Your library is kept in this browser's storage. How much it can hold depends on the browser and the free space on your device.
- Clearing this site's data in the browser erases the library, so keep a backup with Download backup.
- An optional account syncs your books between devices, encrypted in your browser first. It holds 250 MiB of books, each up to 50 MiB. Finepress Pro holds 10 GiB, each book up to 200 MiB.
Finepress is free to use and needs no account. Your PDF is converted in your browser.
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