Convert EPUB/PDF and other formats into local HTML pages, then read in Chrome and translate to your language using built-in browser translation. No API key, no subscription, no ceremony required.
Doc-HTML-Translate comes in several forms; they share the same converter and the same "hand the browser clean HTML, let it translate" idea. Pick whichever fits.
doc-html-translate.exe, the command-line converter and Windows file-association handler. This page documents its flags.doc-html-ui.exe, a windowed front-end that exposes every flag below, with a file picker, drag & drop and a default-handler toggle (opt-in, off by default).The most convenient everyday scenario, and yes, "free" really does mean free:
Why: no API key setup, no paid translation calls, very fast startup.
EPUB, PDF, TXT, Markdown, FB2, RTF, HTML, MOBI, AZW3, and CBZ/CBR/CB7/CBT comics. A reasonable spread, if we say so ourselves.
Also comic archives (CBZ / CBR / CB7 / CBT): a container of page images with no text layer, opened page by page with OCR forced on, so the speech-bubble text is recognized and laid over each page as translatable plates. CBZ and CBT need nothing extra; CBR and CB7 require 7-Zip installed (the same external-tool pattern as MOBI needing Calibre).
Also a standalone image (PNG, JPG, JPEG, WebP, GIF, BMP, TIFF): the app OCRs it and lays translatable text plates over the picture, so Chrome/Edge page translation works on it in place - the same overlay the browser extension produces. Needs the Tesseract OCR engine (see -ocr-lang).
MOBI and AZW3: requires Calibre installed. CBR and CB7 comics: require 7-Zip installed (CBZ and CBT need nothing extra). DRM-protected files are not supported - the converter respects locks it cannot pick.
Plain-text (.txt) input is decoded by sniffing its bytes - a UTF-8/UTF-16 byte-order mark, then valid UTF-8, then a legacy Cyrillic code page (Windows-1251, KOI8-R, CP866) by detection - so a DOS-era or Notepad "Unicode" .txt reads as text, not mojibake. An unreadable binary (a .docx, .djvu, or a comic archive with no 7-Zip) is refused with a named format instead of being turned into a garbage document.
The generated HTML carries a small, fully client-side reader layer - no server to babysit, works happily on file://:
index.html) cycles Light / Sepia / Dark / Night. Your choice is stored in localStorage and applied on every page.index.html shows a "Continue reading" link to the last page you were on, and the navbar carries a thin progress bar across the whole book.-max-cost N turns the cost estimate (chars / 1e6 * $20) into a hard pre-flight limit: if the estimate exceeds N, translation is skipped and the book is still produced untranslated.Single-page documents have no navbar and therefore no reader layer.
The app works out of the box for EPUB, TXT, FB2, RTF, HTML, Markdown. The tools below are strictly optional - install them only if you want full PDF image support and the extra formats.
| Tool | Purpose | Needed for | How to install |
|---|---|---|---|
| pdftotext (Xpdf / Poppler) |
High-quality PDF text extraction - handles complex fonts, ligatures, multi-column layout better than the built-in library | PDF files - optional, built-in fallback used when absent | xpdfreader.com → "Xpdf tools" or already included in Git for Windows |
| ffmpeg | Converts JPEG 2000 images (.jpx) extracted from PDFs into JPEG - browsers still politely refuse to display JPEG 2000 in 2026 | PDF files that contain JPEG2000-encoded images (common in commercial PDFs) | gyan.dev/ffmpeg → "release essentials" or winget install ffmpeg |
| Calibre | Converts MOBI / AZW3 to EPUB before processing | Required for MOBI and AZW3 format support | calibre-ebook.com |
| 7-Zip | Unpacks CBR (RAR) and CB7 (7z) comic archives into their page images | CBR and CB7 comics - CBZ and CBT need nothing extra | 7-zip.org |
Without pdftotext: built-in Go PDF reader is used (slightly lower quality). Without ffmpeg: JPEG2000 images in PDFs will not be visible in the browser. Without Calibre: MOBI/AZW3 files cannot be opened. Without 7-Zip: CBR/CB7 comics cannot be opened.
All optional. The defaults are sensible, so you can ignore this whole table until you have an opinion.
| Flag | Default | Description |
|---|---|---|
| -notranslate | false | Convert only, skip translation |
| -noopen | false | Do not auto-open browser |
| false | Google Cloud Translation API | |
| -ollama | false | Local Ollama translation |
| -ocr | false | OCR text inside document images and overlay it as translatable HTML (needs Tesseract) |
| -ocr-lang | (-src) | OCR language(s), e.g. eng or eng+rus (defaults from -src, else eng) |
| -ocr-langs | false | List installed/available OCR languages and exit |
| -ocr-download | empty | Download an OCR language pack (e.g. -ocr-download rus) and exit |
| -max-cost | 0 | Abort paid translation before sending if the estimated cost in USD exceeds N. When in doubt, 0 (no limit) is a perfectly respectable choice |
| -split | 5000 | Split pages at N chars, 0 disables split |
| -toc-depth | 0 | Table-of-contents nesting depth on index.html, 0 = unlimited, 1 = chapters only |
| -folder | empty | Custom output parent folder |
| -src | en | Source language |
| -dst | ru | Target language |
| -ui-lang | (system) | Interface language: en ru uk de it es fr pt ar hi bn ur zh. Empty follows the Windows language |
| -force | false | Rebuild even if output exists |
| -register | false | Opt in to becoming the default handler for EPUB, PDF and other supported files (off by default; also the default-handler toggle in the doc-html-ui app). The first run only adds the right-click entry and offers this. |
| -unregister | false | Release the default-handler association (keeps the "Convert to HTML" right-click entry and "Open with"). |
| -register-openwith | false | Add the app to the Windows "Open with" list and the "Convert to HTML" right-click menu, without making it the default handler. The doc-html-ui app does this automatically on launch, so the app is always reachable even if you never set it as default. |
Every option above is also available in the doc-html-ui graphical app - file picker, drag & drop, TOC depth, spending guard and a default-handler toggle (opt-in, off by default; the app always adds the "Convert to HTML" right-click entry). On the Microsoft Store build the GUI is the launchable entry point, while double-clicking a file still runs the command-line converter.
For documents that are pictures, not text - screenshots, manga, photographed or scanned pages, the things a text converter cannot read your mind about -
use FastMediaSorter LITE, a free Windows app for opening and sorting images and videos with built-in
OCR + on-image translation. Press T on any image to recognize the text and overlay
the translation in your language (local Ollama or LibreTranslate). It complements Doc-HTML-Translate, which targets
ebook and text formats.
The interface of the application and the extension is available in 13 languages: en ru uk de it es fr pt ar hi bn ur zh. English, Russian and Ukrainian are author-proofread; the other ten are machine-translated and unproofread - corrections are welcome at sza@ukr.net.