FreePDF

FreePDF is a free, open-source Mac app that lets you read PDF files and translate their content — paragraph by paragraph or page by page — without leaving the document viewer.

What is FreePDF?

FreePDF is a lightweight PDF reader built specifically around one killer feature: inline translation. Rather than copying text into a separate browser tab or firing up DeepL alongside your reading session, FreePDF brings the translation directly into the reading experience. It lives on GitHub, it costs nothing, and it targets anyone who routinely wrestles with documents in a language that isn't their first.

The project is open source, which means you can inspect exactly what it does with your documents — a non-trivial concern when the content you're reading is confidential research, legal filings, or proprietary technical specs.

What does FreePDF do best?

FreePDF's strongest suit is reducing the friction of reading foreign-language PDFs. Where the usual workflow is copy → switch app → paste → read → switch back, FreePDF collapses that into a single interaction inside the viewer itself.

• Inline paragraph translation — select a block of text and get a rendered translation without any context switching.
• Readable rendering — the PDF canvas is clean, scroll is smooth, and the translated output is presented in a legible overlay rather than a cramped tooltip.
• Zero cost — there is no subscription, no pro tier, no nag screen. It is simply free.
• Open-source transparency — the full source is on GitHub, so privacy-conscious users can audit the network calls before trusting it with sensitive material.

I've found it particularly useful for academic papers in Chinese, German legal texts, and Japanese hardware datasheets — document types where the original formatting matters but the language is a barrier. The translation quality naturally depends on whichever engine FreePDF delegates to, so it inherits the strengths and weaknesses of that backend.

Is FreePDF free?

Yes — FreePDF is completely free to download and use. There is no paid tier, no in-app purchase, and no account required. Because it is open source, anyone can inspect, fork, and modify the code. Depending on which translation backend the app connects to, you may need an API key for that service (some translation APIs have free tiers with usage caps), but the application itself carries no price tag.

Who should use FreePDF?

FreePDF is a natural fit for researchers, academics, engineers, and legal professionals who regularly encounter PDFs in languages outside their fluency. If you spend meaningful time reading white papers, patents, international contracts, or foreign technical manuals, the context-switch cost of a separate translation tool adds up fast. FreePDF removes that tax.

It is less suited to users who only need a general-purpose PDF reader. For pure reading and annotation workflows, more mature apps like PDF Expert, Skim, or even Preview offer richer annotation toolsets and tighter macOS integration. FreePDF's value proposition is narrow and deliberate: translation-first reading. If that isn't your primary pain point, look elsewhere.

What are the best FreePDF alternatives?

The closest direct alternatives combine PDF reading with translation access:

• PDF Expert — polished commercial reader with annotation depth that far exceeds FreePDF, but translation requires you to copy out manually or use a separate tool.
• Skim — a beloved free, open-source academic PDF reader with strong annotation support; no built-in translation.
• Preview — macOS's built-in reader is fast and tightly integrated but has no translation layer whatsoever.
• Adobe Acrobat — the industry standard, and recent versions have added AI-powered reading aids, but it is expensive and heavyweight for most solo-user workflows.
• Pairing Skim with a browser-based translator remains the power-user workaround, but it requires discipline to maintain the context switch habit.

FreePDF's niche is that it bundles both capabilities in a single free app — something none of the mature commercial readers currently do out of the box without add-ons.

How actively maintained is FreePDF?

FreePDF is an actively maintained open-source project hosted on GitHub. As with many community-driven tools of this type, update cadence can be irregular — it doesn't have the engineering resources of a commercial product. That's a real consideration: if a macOS update breaks something, you're relying on the community rather than a dedicated support team. Following the repository and watching for issues before upgrading macOS is prudent practice.