KoruPDF: Spanish PDF Reader & Dictionary

The reading tool built for language learners.

KoruPDF is the Spanish PDF reader built for language learners. Open any Spanish PDF and the words YOU don't know are underlined automatically — hover for instant meanings, click for the full dictionary. Your PDFs never leave your browser. SMART ANNOTATIONS Translators translate everything. Dictionaries don't know what you know. KoruPDF underlines only the words you're likely missing — based on your own vocabulary level — so you keep reading without stopping. Hover for a quick meaning and move on. INSTANT DICTIONARY LOOKUP Click any word for the full dictionary entry with IPA, examples, and part of speech. Long-press to save it to your vocabulary. Right-click any selected text → "Look up with KoruPDF", or type koru + space + word in the address bar for instant lookup. AI CONTEXT ANALYSIS Wonder why a word means something unexpected here? "Why this word here?" explains the word's meaning in THIS sentence in 2-3 sentences — right in the lookup card. VOCABULARY THAT STICKS Saved words are tracked across documents with encounter counts, mastery levels, and spaced challenge quizzes. Four mastery-based highlight colors show your progress inside every PDF. Export to CSV or Anki anytime, or import your existing word list. READING-FIRST DESIGN Focus reading mask dims everything except the sentence you're reading — after 15 minutes, KoruPDF detects fatigue and suggests it. PDF overview tells you how many new words to expect before you start. My Library keeps your reading history. Not sure what to read? Built-in graded sample readers plus curated free graded readers from university programs, matched to your level. PRIVACY FIRST All PDF processing happens locally in your browser. No PDF content is ever uploaded. Only anonymous event counts and optional feedback are sent. AI features send only the word and up to three sentences of context for analysis. Delete all your data anytime in Settings. See the in-app Privacy Policy for details. FREE VS. PRO KoruPDF is free to use forever — reading, dictionary lookup, TTS, vocabulary saving, highlights, reading mask, and PDF overview are all unlimited. Smart annotations and AI context analysis share 5 free uses per day. KoruPDF Pro unlocks unlimited smart annotations, unlimited AI context analysis, and multi-device vocabulary sync. Pro is a monthly or annual subscription processed by Waffo Pancake (Merchant of Record). Monthly starts with a 30-day $1 trial, then $4.99/month; annual is $39/year. 14-day money-back guarantee. INVITE A FRIEND, BOTH GET PRO Share your invite link — when a friend joins, you both get 14 days of Pro free. Limit: 3 friends (42 days max).