CIRCØ reads PDF documents right in your browser and lets you select any text to translate it instantly. PDFs render with a real text layer, so you can highlight a word or phrase exactly like in a desktop reader — then see the translation in a popover. No account, no install, and the document never leaves your device.
Open a PDF in CIRCØ →Open any .pdf file at circ0.com, choose your language pair, and select a word or phrase on the page. The translation appears in a popover instantly — no page reload, no copy-pasting into another tab.
Most PDF translation tools — including Google Translate's document mode and DeepL — translate the entire file at once, often breaking the original layout and stripping formatting. CIRCØ takes a different approach: it keeps the original PDF rendering intact and only translates the specific words or sentences you select.
This selective translation is better for language learners because you stay in the document and translate only the parts you don't understand. It's also better for privacy: the full document is never uploaded, and only tiny text snippets leave your device. Here's how CIRCØ compares to common alternatives:
CIRCØ supports nine languages for both the source and target: English, Spanish, French, German, Italian, Portuguese, Russian, Japanese, and Chinese. Set any combination as your From/To pair. Whether you're reading a French research paper and translating to English, or working through a German novel, you can switch languages at any time without reloading the document.
CIRCØ renders PDFs with a transparent text layer over each page, giving you native text selection just like a desktop PDF reader. The reader is designed for long reading sessions with academic papers, textbooks, and foreign-language documents.
Yes — that's exactly what CIRCØ is designed for. Instead of machine-translating every sentence (which often produces awkward results for technical or literary text), you read the original and translate only the words you don't know. This "selective translation" approach is widely recommended by language teachers because it forces you to engage with the source text and build vocabulary through context.
Every word or phrase you translate is automatically saved to your vocabulary list. Over time, you build a personal dictionary of terms you've encountered across all your documents — PDFs, EPUB books, comics, and even video subtitles.
CIRCØ is completely free — no account, no subscription, no usage limits. Privacy is a core design principle: your PDF file is rendered locally using pdf.js and is never uploaded to any server. Only the short text snippet you select for translation is sent off-device. Your reading position, highlights, and saved vocabulary stay in your browser's local storage and are never collected. See our privacy policy for full details.
No. CIRCØ runs entirely as a web app at circ0.com — no browser extension, plug-in, or desktop software required. It works in Chrome, Firefox, Safari, and Edge on both desktop and mobile. You can also install it as a Progressive Web App (PWA) for quick access and offline reading directly from your home screen.
Work through research papers, textbooks, or foreign-language documents and translate just the terms you don't know — without breaking your reading flow or copy-pasting into another tab. The built-in vocabulary tracker saves every word you look up, letting you review and quiz yourself later with spaced-repetition exercises. Everything stays private: only the text you select is sent for translation, and your reading data stays in your browser.
Read & translate a PDF →Questions? Email circ0@circ0.com. See our privacy policy and terms of use.