VireBook

Browser extension: a whole book as EPUB, MOBI, FB2 or TXT — in one press.

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No "download → wait → pick a format → wait" chain: the book is assembled right in the browser. The extension walks the chapters, pulls the text out of the HTML and glues the file together locally. The site's server generates nothing, so there is nothing to wait for.

The interface is a panel made of VireGlass: refraction of the live DOM, not a CSS shadow. The pane can be thrown into any corner of the window.

Formats	EPUB · MOBI · FB2 · TXT
Sites	ficbook.net · AO3 · fanfics.me · fanfiction.net · wattpad.com · royalroad.com · any other
Sends outwards	nothing by default — no <all_urls>, no screenshots. Only if you turn on translation, chapter text goes to Google Translate
Licence	MIT

Installing

1. Download the repository (Code → Download ZIP) and unpack it, or git clone it.
2. Open chrome://extensions (in Yandex Browser, browser://extensions).
3. Turn on Developer mode — the toggle at the top right.
4. Press Load unpacked and point at the repository folder (the one with manifest.json in it).
5. Done. The icon appears to the right of the address bar.

The same works in Chrome, Edge and Yandex Browser. No build step is needed: dist/ is committed ready to run.

After installing, do not delete or rename the folder: the browser loads the extension from it on every start.

Using it

On a book page a Download book button appears at the bottom right. Press it → pick a format → the file downloads.

The pane is in the way? Throw it somewhere else. Drag it with the mouse and let go: it lands in the nearest corner of the window. From the keyboard, Alt+arrows do the same. The chosen corner is remembered and holds across all sites until you change it again.

If the site is unknown and no button appeared, click the extension icon in the toolbar and choose Show the button on this page.

The same popup is where the default format is set — it moves to the top of the list.

Translating a book

Reading a book that is not in your language? In the panel, Translate (above the formats) takes a target language — Русский, English, Українська, Deutsch, Français, Español, Italiano, Português, Polski, Türkçe, 日本語, 中文, 한국어. It is Off by default, and the choice is remembered.

With a language picked, the book is read as usual and then translated before the file is written, so EPUB, MOBI, FB2 and TXT all get it: chapter text (paragraphs, italics and bold intact), chapter titles, author's notes, the book's title and its summary. The author, tags and fandom stay as they are, and the file's language is set to the target. The first chapter is translated first, and if Google reports that the chapter text was already in the target language, the rest is not sent and the book is downloaded as it is. If Google keeps refusing some chapters, those stay in the original language, the rest is translated, and the panel says how many.

This is the one thing that leaves the machine. The chapter text is sent to Google Translate's public web endpoint, in batches, spaced out; nothing is sent unless translation is on. The panel says so under the control. With translation on, a site's own ready-made file (AO3's) is not used, since it cannot be translated.

Getting the file onto a Kindle 11

EPUB is the main route. Amazon converts it itself, and the table of contents and italics survive:

• by mail: send the file as an attachment to an address like name@kindle.com (it is in the device settings on amazon.com → Manage Your Content and Devices → Preferences → Personal Document Settings). You must send it from the address listed as approved in that same place, otherwise the mail silently never arrives;
• or through Amazon's "Send to Kindle" web uploader — drag the file in the browser.

MOBI is the cable route. Plug the Kindle into the computer, copy the file into the documents folder on the device, unplug.

FB2 — for a phone and PocketBook; a Kindle does not read it. TXT — if nothing else worked out.

Which sites

Site	How it works
ficbook.net	Own parser. Markup checked against the live page on 2026-09-15
archiveofourown.org	Takes the site's own ready-made file (AO3 builds EPUB/AZW3/MOBI itself — instant and of higher quality)
fanfics.me	Own parser, markup unverified — see "Honest limitations"
fanfiction.net	Own parser against the known markup, not verified live
wattpad.com	Own parser, the text comes from the site's internal endpoint
royalroad.com	Own parser
any other	Generic reading: finds the most text-like block on the page, then either a table of contents or the "next chapter" links

The generic reading is also the fallback: if a listed site is restyled and its own parser misses, the extension moves over to it silently.

Honest limitations

Worth knowing before you rely on it:

• MOBI has not been verified on a live Kindle 11. The format is built to spec and is parsed back in the tests (headers, table of contents, filepos offsets), but I do not own the device. Amazon lists MOBI among the formats supported for a cable upload; if it does not open, the working route is EPUB + Send to Kindle. Best to check that in advance, on a single book.

• fanfics.me is unverified. The site answers "unavailable in your country" outside Russia, so the markup could not be captured. The selectors are written speculatively, with the generic parser as the safety net. From Russia this takes a minute to check.

• fanfiction.net and Wattpad are written against the known structure and were not exercised live: the first has bot protection, the second keeps its text behind an internal API.

• Images do not make it into the book — text only. For most books that is what you want, and the file comes out lighter.

• Paid and restricted chapters download only if they are open in the browser: requests carry the reader's own cookies, that is, exactly what is already on their screen.

• Translation is machine translation, over an unofficial endpoint. It reads like Google Translate reads, and the endpoint has no key and no promise: Google can slow it down or turn it off, in which case the panel says it was refused — set Translate to Off to download the book as before. A long book takes a minute or two longer.

If something breaks

Sites get restyled — that is normal and is fixed one file at a time.

• No button appeared → extension icon → "Show the button on this page".
• "No text found" → it almost always helps to open the page of the whole work rather than a single chapter.
• Downloaded empty or truncated → the chapter body selector changed. Fixed in src/adapters/<site>.ts, which holds a list of candidates — usually adding one new class is enough.

The glass

The extension's panel is made of the VireGlass material, from the vireglass package on npm: the causes of the material (ior, thickness, bevel, roughness, legibility, presence) are set by the model, and the consequences — refraction, rim, body, shadow and the response to a finger — follow from them.

The package ships a renderer for exactly this case, attachGlass from vireglass/dom, and src/glass.ts is a port of it rather than a second implementation: every number is imported. What is worth knowing before changing anything here:

• Two things keep this a port instead of a call to attachGlass. The first is the finger. The pane answers a touch by moving — it lags behind on the core's pull spring and sinks under a press — and that is a transform on the whole widget, which no material can apply for it; GlassHandle hands out neither the spring's state nor a way to drive it. The gesture has to be ours in any case, because on this pane a drag is not a drag of the material but a throw into another corner of the window, and only the widget knows which is which. The second is the morph: attachGlass re-reads the backdrop and re-bakes the map at full device resolution on every resize, which while the panel is changing shape means every frame. Here the map is built once for the shape the pane is travelling to and stretched over the live box until it lands.

  What is not a reason any more is the shadow DOM. Up to 2.1.0 attachGlass put its filter <svg> on document.body and its rim stylesheet on document.head, and a widget in a shadow root could use neither — a document stylesheet does not cross the boundary, and backdrop-filter: url(#id) used from inside a shadow tree resolves against that tree, so the filter is simply not found and the pane gets no backdrop at all, not even the blur fallback, because the reference itself is perfectly valid CSS. 2.2.0 finds the element's own root. The filter here still lives in the shadow tree for the same reason, just by our own hand.

• The refraction is of the live DOM, not of a snapshot. The browser never hands a page's pixels to script — that boundary is the whole reason backdrop-filter exists — so the displacement happens in the compositor: backdrop-filter: url(#vg-refract) over an feDisplacementMap whose map the package bakes from the pane's shape and its optics. Live, permission-free, never stale.

• The filter must carry color-interpolation-filters="sRGB". By default SVG computes a filter in linearRGB, and that breaks both of its halves at once. The neutral middle of the map (128) reaches feDisplacementMap as 55 — a shift of a third of the scale, which means the whole backdrop under the pane slides diagonally by ~9 px and the rim drags in whatever lies outside it. The same linearRGB washes out the scattering: over a dark page the pane starts glowing instead of lying there. Remove the attribute and you get back exactly the rim artefacts it exists to prevent.

• The refraction layer lives in a nested clip (.shell > .clip > .refract) rather than on the shell itself. It is wider than the sheet by --slack: the blur and the displacement need something to gather under the edge. The slack must not be added to the filter region — then backdrop-filter spills the filtered background past the element's bounds and a rectangle shows around the rounded shape; here the spill is cut off by overflow. The separate .clip is needed for its own reason: while backdrop-filter sits directly in the shell, whose height is moving through a morph, and the sheet is pinned by its top, Chromium stops recomputing the position of the neighbouring layers — the panel's content stays lifted by a couple of dozen pixels.

• The material is a sheet, not clear glass. Roughness is taken at the ceiling of the model (MATERIAL_RANGES.roughness[1]): the sheet lies over a LIVE screen and must not be transparent — the page reads through it and argues with its own labels. The cause is roughness, not darkening. The rest of the causes come from VIREGLASS_CONTROL_MATERIAL: it is a control after all, and needs thickness, a bevel and presence.

  The body — how much medium stands between the page and the eye, and which way it tints — is resolveBody/withPresence from the package, and CSS only paints what they return.

• The backdrop is read from declared styles, not from pixels, which is the package's documented limit and not a shortcut: the browser never hands a page's pixels to script. probeBackdrop walks the stacking order under a grid of points and composites what it finds, down to the canvas — which matters here, because a pane pinned to a window corner usually hangs past the end of the body box, where the only element beneath it is a transparent <html>.

• Ink polarity is the application's decision, not the material's: shouldInkBeLight() over that reading. Without it, over a light page the pane becomes a grey slab with unreadable text. The package's CONFIRMATIONS is deliberately not used: it counts readings and is sized for a renderer that takes them about five times a second, while this one reads on events — at mount, when a scroll stops, when the pane lands. Three of those can be a minute apart. The hysteresis inside shouldInkBeLight is what keeps a cover sliding under the edge from recolouring the panel.

• The cursor response is part of the material, and it has to be let out. The springs for press, pull and wave are the package's createDeform(); only the gesture comes from here. The map is rebuilt around the contact point every frame while a finger is down, and what the map cannot carry — the pane lagging behind the finger, the sink under a press — is handed back to the widget for the transform. A press makes the medium denser and cleaner: that is activeMaterial, and blur goes 12 → 3 while the bevel widens and the index rises. Deliberately not raiseIntoGlass, which the package's own DOM renderer uses here — that one is for a control which is not glass at rest and materialises into it, and it takes roughness to nothing at a full press. This pane is glass already and is lying over a page of text: clear it completely and the chapter comes through sharp behind the panel's own labels.

• Dispersion is skipped when it would not show. Per-channel refraction costs three displacement passes, three colour matrices and two composites, per frame. refractionStrength saturates at n = 1.6 and this material sits at 1.69, so the shifted indices land on the same full strength and all three channels ask for the same scale — the single-pass picture, exactly, for three times the work. src/glass.ts builds the three-pass graph only when the ratios actually come out apart.

If backdrop-filter is missing entirely the panel falls back to a flat material and stays usable — just without the glass. Where backdrop-filter works but a filter reference does not (Firefox, older Safari), the package's own fallback stands in: blur and saturation from the same optics.

Development

npm install         # vireglass, plus the build and test tooling
npm run build       # bundle src/ → dist/ (this is what the browser loads)
npm run typecheck   # tsc --noEmit, strict
npm test            # formats + adapters
npm run check       # all three of the above, in the order CI runs them
npm run demo        # serve test/ui-demo.html on localhost:5599 to look at the panel
npm run icons       # redraw the icons

There is one runtime dependency, vireglass, and it is bundled into dist/ along with everything else — the extension still installs as a folder with no node_modules in it.

The whole source tree is TypeScript under strict. Node 24 runs the sources and the tests directly by stripping types, so there is no compile step for testing; tsc is only ever asked whether we are wrong. The browser gets bundles from esbuild.

The widget is looked at on test/ui-demo.html: a stand-in book page with three backgrounds (light, dark, grid). The glass has to read on all three, and the pane has to travel to all four corners.

About dist/. It is committed on purpose. Installing should be "load unpacked and you are done" — the readers this is for should not need node and npm to get a button on a page. CI rebuilds dist/ and fails if the result differs from what is committed, so a stale bundle cannot slip through. After changing anything in src/, run npm run build and commit the result.

The tests do not take "the file was built" for an answer: EPUB is unpacked and checked for well-formed XML, MOBI is taken apart by PalmDB record and decompressed again, table-of-contents offsets are verified against the anchors. Adapters run against fixtures captured from the structure of live pages (the prose in them is ours, not anybody else's).

Layout

manifest.json          — MV3; points at dist/
src/types.ts           — Book, Chapter, Adapter, ParseContext: the shared vocabulary
src/chrome.d.ts        — the slice of the extension API we use, hand-written
src/lib/               — formats and utilities
  zip.ts               — ZIP (store + deflate-raw) for EPUB
  html.ts              — chapter cleanup and XHTML serialisation
  epub.ts  mobi.ts     — assembling the book
  fb2.ts   txt.ts
  util.ts              — pacing, backoff, filenames
src/translate/         — optional translation: the engine interface, the Google engine,
                         batching, and translating a whole Book
src/adapters/          — one file per site, plus base.ts, generic.ts and the registry
src/glass.ts           — the material: vireglass/dom's renderer, ported into a shadow tree
src/core.ts            — choosing an adapter, fetching chapters, saving the file
src/ui.ts              — the floating panel (shadow DOM, and the layers the glass writes into)
src/content.ts         — the entry point on a page
src/popup.ts           — the toolbar popup
src/background.ts      — the default format on install
dist/                  — the bundles the browser loads (committed, built by CI too)

Contributing

The main place effort pays off is the site adapters: sites get restyled, and that is fixed one file at a time, without knowing the rest of the code. How to fix a broken site and how to add a new one is in CONTRIBUTING.md. Something broken, or a site you want added — open an issue.

Version history is in CHANGELOG.md.

Privacy

The extension reads exactly the pages that are already open in the browser and sends nothing anywhere by default: neither the assembly nor the file leaves the machine, and the only requests are to the book's own site. The exception is translation, which is off until you turn it on: then the chapter text (and the title and summary) goes to translate.googleapis.com, and nowhere else. Every request is in src/core.ts, src/translate/google.ts and the adapters — verifiable by searching for fetch. Downloading is for personal reading.

Permissions are the minimum: storage (the default format, the translation language and the corner the pane sits in), activeTab and scripting (the "show the button on this page" action). No <all_urls>, no screenshots — the glass makes do with the live DOM.

Licence

MIT, see LICENSE.