One Android reader for EPUB, PDF, MOBI and comics

Short answer: Lectern opens EPUB, EPUB3, KEPUB, MOBI, AZW, AZW3/KF8, PRC, FB2, FBZ, TXT, PDF and CBZ/CBR/CB7/CBT comics in one app. Reflowable text formats share one full reader: typography, read-aloud, dictionary and highlights. PDF and comics work differently, since pages are fixed or image based, though a text PDF can be reflowed into that same full reader.

Checked in September 2026 against Lectern 1.31.

“Reader” is Lectern’s text reader: the same screen, settings and library position for every reflowable format. “Via reflow” means the feature only shows up once you open a text-based PDF as reflowed text rather than as page images; details below.

Reflowable ebooks: EPUB, MOBI, FB2, TXT

EPUB, EPUB3, MOBI, AZW, AZW3 (also called KF8), PRC, FB2, FBZ and plain TXT files all land in the same reader, because Lectern parses every one of them down to the same internal chapters-and-paragraphs structure before it draws a page. That has a practical upside: font, size, line spacing, margins, theme and the rest of the typography settings behave identically whichever of these formats you opened, and so do read-aloud (system voices, or the offline Piper and Kokoro neural voices), dictionary lookup on a selected word, saved highlights and in-book search.

A few things differ under the surface. MOBI is the old Mobipocket format from the late 1990s, built on HTML from before CSS was common, so its own typography is thin; AZW3/KF8 fixed most of that with real CSS support. AZW itself is usually plain MOBI wrapped in Amazon’s Kindle Store DRM, so most .azw files people actually have will not open at all (see the DRM section below); a genuinely DRM-free .azw opens the same as any MOBI. FB2 is XML with the images stored inline as base64, and FBZ is that same file zipped. TXT files get their character encoding auto-detected rather than assumed, and are split into virtual chapters so the table of contents has something to point at. None of that changes what you can do once the book is open: it only affects how faithfully the original formatting survives the trip.

Kobo’s own KEPUB format is a plain EPUB zip with extra markup for its reading-progress features; Lectern treats it as EPUB directly, so a .kepub file opens with the full reader like any other EPUB. Calibre usually names its output .kepub.epub, which already has a recognized extension; a bare .kepub is recognized too.

Fixed-layout EPUB and picture books

Some EPUBs are pre-paginated: the OPF explicitly says so, and each page is really one full-page image rather than reflowable text (children’s picture books and heavily designed magazines both do this). Reflowing that kind of book wouldn’t produce anything readable, so Lectern opens it in the comic viewer instead, page by page, exactly like a CBZ.

One exception: a fixed-layout EPUB that also carries EPUB3 Media Overlays (the author’s own recorded narration, synced sentence by sentence to the text) stays in the regular reader, so that built-in read-along narration keeps working. Lectern marks those books with a headphones badge, and it plays the author’s audio rather than text-to-speech; if a chapter of the book has no narration of its own, Lectern offers to read that part aloud instead.

If a fixed-layout EPUB opens as image pages and you’d rather have it as text, the book’s detail sheet has an “Open as text” option that drops the fixed-layout hint and reflows the underlying HTML into ordinary chapters, with the full reader’s dictionary, highlights, search and read-aloud. A page that was designed as a single picture obviously loses that original layout in the process.

PDF: text-based versus scanned

PDF gets its own viewer with three view modes: continuous scroll, page by page, and reflow text. The first two show the page exactly as designed, with search, dictionary lookup on selected text, a table of contents from the PDF’s own bookmarks, brightness, a warmth (blue-light) filter, night and sepia colour modes, and pan locks when zoomed in. What they don’t have is read-aloud or saved highlights: text selection in this mode is for search and lookup, not for keeping.

Reflow text is the more capable mode, but it only works when the PDF actually has a text layer to work from. When it does, Lectern reconstructs real paragraphs from the underlying text runs (including de-hyphenating words split across a line break and keeping footnotes and internal links intact), and opening a PDF this way, or tapping Listen directly from the book’s detail sheet, sends it into the exact same reader as an EPUB: full typography settings, dictionary, saved highlights and read-aloud all work.

A scanned PDF, where each page is a photograph of paper rather than text, has no text layer to reflow. Lectern says so plainly: “This PDF has no text layer to reflow (it looks like scanned images). Use page or scroll mode instead.” There is nothing to search, look up or hear read aloud on a scanned page, only the page image itself.

Comics: CBZ, CBR, CB7, CBT

Comic archives open in a dedicated viewer built for images, not text: page by page or continuous scrolling, pinch zoom, tap zones or volume buttons to turn pages, brightness and warmth, and a choice of background colour. If the archive includes a ComicInfo.xml file (common in scanned and scanlated comics), Lectern reads it automatically for series and issue metadata, right-to-left manga reading order, and which pages are double-page spreads, without asking you to set any of that by hand.

What a comic page never gets is read-aloud, dictionary lookup, saved highlights or search, because a comic page is a picture, not text Lectern has parsed. That applies equally to CBZ, CBR, CB7 and CBT: the format only decides how the images are packaged.

Packaging is where CBR has one real gap. CBZ (ZIP), CB7 (7-Zip) and CBT (TAR) always open. CBR (RAR) opens for classic RAR4 archives and for RAR5 archives whose entries are stored uncompressed, which is common for comics since JPEG pages don’t compress further anyway. A RAR5 CBR that actually uses RAR5’s own compression, solid archiving or encryption does not open, on purpose: supporting it would mean shipping a multi-megabyte native RAR5 library for a case that’s rare in practice. Lectern says so directly: “This CBR uses RAR5 compression that isn't supported. Convert it to CBZ to read it.” Re-zipping the same images as CBZ with any archive tool fixes it in a minute.

DRM: what Lectern won’t open

Lectern only opens DRM-free files. There is no Adobe ADEPT support, no Readium LCP support, and no Kindle, Kobo or Google Play Books store decryption, by design, since Lectern has no account and never talks to a store. A book bought from one of those stores, opened straight from its original download, will not open.

Lectern checks for this rather than failing with a cryptic error. EPUB is checked against its META-INF/encryption.xml (careful to ignore the harmless font obfuscation that many EPUBs use, which only touches embedded font files, not the text); MOBI, AZW and AZW3 are checked for Kindle/Mobipocket encryption. A book that fails this check shows up in your library labeled “Copy-protected book”, with the explanation: “Books from the Kindle, Kobo or Google Play stores are DRM-protected and cannot be opened by Lectern or any other third-party reader. A DRM-free or watermarked edition will work.” If scanning turns up any, a dismissible banner on the library shelf says how many, rather than leaving you to find each one by trial and error. The full picture, including what DRM-free and watermarked actually mean, is in ebook DRM explained.

Importing a mixed folder

A real folder of files is rarely just ebooks. Lectern scans by kind rather than assuming: each library folder remembers whether to include Books, PDFs and Comics, so a Downloads folder that also holds PDF manuals or a stray comic archive can be limited to just the ebooks in it, or opened up to all three. The extensions recognized per kind are epub/kepub, fb2/fbz, mobi/azw/azw3/prc and txt for Books; pdf for PDFs; and cbz/cbr/cb7/cbt for Comics.

Getting a mixed folder onto the phone in the first place doesn’t need a cable or an account: sending books over Wi-Fi opens a small server on the phone that a computer on the same network can drop files into directly. Once a folder has grown past a handful of titles, cleaning up author names, series and covers is its own small job, covered in organizing a digital library.

Legacy files worth knowing about

MOBI itself is a retired format: Amazon stopped accepting it through Send to Kindle in 2022. Lectern still opens plain MOBI, AZW3 and PRC files today, so an old library stays readable, but the tooling and the standards work have moved to EPUB; MOBI vs EPUB covers what changes if you convert. Old TXT files with a legacy character encoding are detected automatically rather than assumed to be UTF-8, so a text file exported years ago should still read as intended instead of turning into garbled characters.

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