Glossa is a web-based language learning app that lets you upload your own PDFs and EPUBs and read them in 13 languages with click-to-translate, audio narration, and built-in spaced-repetition vocabulary practice. It turns any book you already want to read into a graded reader for the language you are learning.

What languages does Glossa support?

Glossa supports 13 languages: English, Spanish, French, German, Italian, Portuguese, Dutch, Swedish, Norwegian, Danish, Polish, Russian, and Turkish. Word difficulty is scored from corpus frequency data, so coverage quality tracks how much text a language has in that corpus. More languages are in preparation.

What file formats can I upload?

PDF and EPUB, up to 100 MB per file. Books upload directly from your browser to Azure Blob Storage via a short-lived signed URL — the application server never sees the raw bytes in transit.

Yes. The free tier includes 2 books and 10 distinct pages of reading, with every feature unlocked (translation, audio narration, vocabulary games). Pro is $14.99 per month or a one-time $4.99 7-day pass, and removes the book and page limits.

What is included in Pro?

Unlimited books, unlimited pages, AI-generated chapter summaries, and faster book processing. Pro removes limits rather than gating features — translation, audio narration, and vocabulary practice are also fully available on the free plan.

Does Glossa work on mobile?

Yes, Glossa runs in any modern mobile browser. There is no native iOS or Android app yet; the responsive web app is the only way to use Glossa on phones today.

Is my uploaded content private?

Yes. Uploaded books are stored in a private Azure Blob container accessible only to your account, are never shared with other users, and are never used to train AI models. We do not sell user data.

What is CEFR scoring and how does Glossa use it?

CEFR is the Common European Framework of Reference for Languages, a six-level scale from A1 (absolute beginner) to C2 (near-native). Glossa scores every word in your book on this scale and a difficulty slider in the reader controls which words get translated inline — lower slider shows more glosses for harder words, higher slider shows fewer glosses and more original text.

How does the spaced-repetition vocabulary practice work?

Words you tap while reading are saved to your vocabulary list. Glossa surfaces them in short games — matching, fill-in-the-blank, multiple choice, parts-of-speech tagging, and sentence-scramble — scheduled so you re-encounter each word at increasing intervals based on how confidently you answered last time.

How is Glossa different from Duolingo?

Duolingo teaches with a fixed curriculum of synthetic exercises. Glossa is a reader — you upload real books you actually want to read, and translation and vocabulary practice are built around that content. Duolingo suits absolute beginners; Glossa suits learners who can read elementary sentences and want to engage with longer material.

How is Glossa different from LingQ?

LingQ has a built-in catalog of curated lessons and a learner community. Glossa lets you upload any PDF or EPUB and adds CEFR-adaptive interlinear translation, which LingQ does not offer. LingQ has more pre-curated content; Glossa gives you more control over what you read.

How is Glossa different from Readlang?

Readlang is primarily a browser extension for translating words in web articles. Glossa is book-centric — built around uploading PDFs and EPUBs, with audio narration, CEFR-adaptive glossing, and structured vocabulary games. Choose Readlang for web articles; choose Glossa for full books.

Can I import books from Project Gutenberg?

Yes. Glossa has a built-in browser for the Project Gutenberg catalog of public-domain titles. Pick a book in your target language and it imports in seconds without leaving the app.

What voices does Glossa use for audio narration?

Azure Neural Text-to-Speech voices, native-speaker quality in each supported language. Every user gets a default voice per language; additional voices can be unlocked using Glossa Points earned through reading.

Where to download free books in your target language

Legal sources, sorted by language — and the ones that look useful but aren’t.

Copyright expires. When it does, the book becomes public domain and anyone may copy, share and read it for free — which is why the entire nineteenth-century canon of most European languages is legitimately downloadable right now, at no cost, from libraries that exist specifically to give it away. This page is a map of those libraries, organised by the language you are learning.

The one thing to check before you start

Most “free books” lists confuse two very different things: sites that give you a file, and sites that only display text in a browser. For a language learner the distinction matters enormously, because a file is what you can load into a reader, annotate, carry offline, and look words up in. A web page is just a web page.

The trap catches German learners hardest. Projekt Gutenberg-DE is the largest German-language collection anywhere — nearly 13,000 titles — and it is the first result almost everyone finds. It offers no EPUB and no PDF. Neither does Zeno.org. If you want a German classic as an actual file, you need one of the alternatives listed below, and knowing that in advance saves an afternoon.

Works for every language: Wikisource

Before the per-language lists, one source deserves singling out. Wikisource is a public-domain library that exists separately in every language Glossa supports, the texts are proofread against scans, and every page can be exported as a clean EPUB — either from the “Download as EPUB” link in the sidebar or through the WS Export tool. When your language has thin coverage elsewhere, this is the reliable fallback.

Wikisource — EPUB, PDF
A public-domain library in every language Glossa supports. Use the “Download as EPUB” link in the sidebar, or the WS Export tool for any page.
Project Gutenberg — EPUB, TXT
The original. 70,000+ titles — overwhelmingly English, but with real depth in French, German, Italian, Portuguese and Finnish too.

By language

Spanish (Español)

Elejandría — EPUB, PDF, MOBI
Roughly 2,300 books, public domain and openly licensed, with no registration and clean EPUB files.
Biblioteca Virtual Miguel de Cervantes — EPUB, PDF
The scholarly Spanish-language archive. Several hundred EPUBs — Galdós, Lorca, Pardo Bazán, Arenal.

French (Français)

Ebooks libres et gratuits — EPUB, PDF, MOBI
A long-running francophone volunteer group; around 2,500 public-domain titles in well-made EPUB.
Bibebook — EPUB, PDF
About 1,300 carefully typeset French classics — fiction, poetry, essays.
Gallica (BnF) — EPUB, PDF
The French national library. Enormous, and strong on periodicals and older editions, though much of it is scans rather than clean text.

German (Deutsch)

Deutsches Wikisource — EPUB, PDF
The most reliable way to get a German public-domain text as an actual file. Proofread, and exports cleanly.
Project Gutenberg (German titles) — EPUB, TXT
A couple of thousand German titles with proper EPUB downloads — the international Gutenberg, not the German site of the same name.
Projekt Gutenberg-DE — read online only, no download
The largest German collection — nearly 13,000 titles — but read-online only. There is no EPUB or PDF download, so you cannot bring these into a reader. Worth knowing before you go looking.

Italian (Italiano)

Liber Liber — EPUB, PDF
Progetto Manuzio, running since the 1990s, with a sub-project (Griffo) dedicated specifically to producing EPUB editions.

Portuguese (Português)

Wikisource em português — EPUB, PDF
The cleanest route to a Portuguese public-domain EPUB, covering both Brazilian and European authors.
Portal Domínio Público — PDF
The Brazilian government archive — very large, but mostly scanned PDFs rather than reflowable text, and it often refuses connections from outside Brazil.

Dutch (Nederlands)

DBNL — EPUB, PDF
The Digital Library for Dutch Literature. Over a thousand EPUBs — Couperus, Multatuli, Van Eeden, Conscience.

Russian (Русский)

Русский Викитека — EPUB, PDF
The dependable legal source for Russian classics as downloadable files. Chekhov, Tolstoy, Pushkin, Gogol.
ImWerden — PDF
A non-commercial scan library of nearly 19,000 publications, strong on rare and small-print-run editions. PDF only.

Polish (Polski)

Wolne Lektury — EPUB, MOBI, PDF
The strongest non-English source we found: over 6,000 titles, properly produced, covering the entire Polish school canon plus world literature in translation.
Polona — PDF
The Polish National Library’s digital collection — millions of scans, best for older and rarer material.

Swedish (Svenska)

Litteraturbanken — EPUB, PDF
Around 1,300 finished ebooks of the Swedish canon — Strindberg, Lagerlöf, Söderberg — with a page dedicated to EPUB downloads.
Projekt Runeberg — PDF, HTML
Nordic literature since 1992, about 5,600 titles. Broad, but most of it is not formatted for e-readers.

Norwegian (Norsk)

Bokselskap.no — EPUB, MOBI, PDF
Over 250 Norwegian classics — Ibsen, Undset, Skram, Collett — published specifically for download. Exactly what you want.
Nettbiblioteket (Nasjonalbiblioteket) — PDF
Nearly every Norwegian book published before 2001, readable online from a Norwegian IP. Only out-of-copyright titles can be downloaded.

Danish (Dansk)

eBibliotek 1800 — EPUB
Nineteenth-century literature hand-prepared as EPUB, including Danish translations of Dumas and Eliot. Small, but the files are properly made. Editions since 2022 are CC BY-NC-SA rather than public domain.
Arkiv for Dansk Litteratur — read online only, no download
The Royal Danish Library’s literary archive — 78 authors and over 10,000 texts from the medieval period onward. Searchable and readable online, with facsimiles, but there is no consumer download; the texts are exposed as TEI through the library’s API instead.

Turkish (Türkçe)

Vikikaynak — EPUB, PDF
The most practical Turkish option, though the catalogue is much smaller than its European equivalents.
Kültür ve Turizm Bakanlığı e-Kitap — PDF
The Ministry of Culture’s free e-book archive. Genuine and free, but weighted towards Ottoman-era and academic texts rather than modern reading.

English

Standard Ebooks — EPUB, AZW3
Around 1,500 classics, hand-typeset from Gutenberg texts and released under CC0. The best-looking free ebooks anywhere.

What we deliberately left out

Search for free ebooks in almost any language and the top results will include shadow libraries — Z-Library, Anna’s Archive, Flibusta, Librusek and their many mirrors. They dominate these searches, they are free, and they have far more books than anything listed above, because they distribute work that is still in copyright without permission.

We don’t link to them. Beyond the legal question, there is a practical one: an author whose book is still selling has an income that depends on it, and the public domain is large enough that you do not need to make that trade to find good reading. Everything on this page is either out of copyright or openly licensed by the rightsholder.

Once you have the file

One thing to keep in mind as you browse: public domain means old, and the oldest books are rarely the easiest. Look for the shorter, plainer work in each catalogue — stories and novellas rather than the doorstop everyone recommends.

And a downloaded EPUB is a starting point, not a solution, because the reason most people abandon their first foreign-language novel is that looking up every third word destroys the reading. That’s the problem Glossa exists to solve: upload the file you just downloaded and it renders with inline translations on the words you don’t know yet, adapting as your vocabulary grows. The free tier covers two books — enough to find out whether reading this way suits you.