About Mamu Library
A free, open catalog of public domain literature for language learners — organized by CEFR proficiency level, searchable by language, and built to work seamlessly with the Leo reading app.
Why this exists
Reading real literature is one of the most effective ways to acquire a language. But finding the right book — at the right level, in the right language — is surprisingly hard. Project Gutenberg has tens of thousands of texts, but no proficiency ratings. Language learning apps have graded readers, but limited catalogs.
Mamu Library bridges that gap: a curated, community-maintained catalog where every entry has a language code, a CEFR level, and a direct link to a free, legal source.
CEFR levels explained
Very short, simple texts. Basic vocabulary, slow pace.
Simple stories and dialogues. Common everyday language.
Familiar topics, moderate vocabulary. Accessible originals.
Complex plots, idiomatic language. Most classic novels.
Demanding prose, nuanced meaning, cultural depth.
Highly literary, archaic, or dialectal texts.
CEFR ratings in this catalog are editorial assessments based on vocabulary density, sentence complexity, and cultural accessibility — not algorithmically generated.
Leo integration
Mamu Library is designed to work hand-in-hand with Leo, the language learning reading app by Mamu Labs. When you open the library from within Leo (on iOS, Android, or the web), you’ll see an “Add to My Leo Library” button on every book detail page. Tapping it sends the book directly into your Leo reading list — no copy-pasting URLs required.
Contributing
The catalog grows through community submissions. If you know a public domain book that belongs here — in any language, at any level — please submit it. Our editors review every entry for accuracy before it goes live.
We especially welcome submissions in under-represented languages: African languages, Indigenous American languages, South and Southeast Asian classics, and oral literature that has been transcribed.
Sources
All books link out to their original sources — we do not host files. Primary sources include Project Gutenberg, Wikisource, Aozora Bunko, and Internet Archive.