KDAN PDF vs Mozilla PDF.js

KDAN PDF is a PDF app for Android, iOS, Mac and Windows, with tools for viewing, annotation, editing and conversion. The free plan includes viewing, notes and annotations, handwriting, signatures and form filling, but not text editing, form creation, OCR or PDF conversion. Document 365 costs USD 59.99 per year and adds text editing, merging and splitting, Office file conversion, OCR for scanned PDFs and password protection. Document 365 AI+ costs USD 99.99 per year and includes those features plus AI services such as auto-redaction, summarization, document review and paragraph translation. Both subscriptions offer a seven-day free trial. A lifetime license costs USD 119.99 per device and covers one desktop device, with offline work that does not require cloud uploads. Paid plans provide read-aloud text-to-speech. Refunds may be requested within 14 days after purchase, subject to store exclusions. KDAN PDF is powered by KDAN Mobile Software Ltd., founded in 2009 and based in Tainan City, Taiwan.

Mozilla PDF.js is a free, web standards-based platform for parsing and rendering PDF files. Developers can use its display API to render documents and retrieve information, or adapt the viewer layer for a custom interface. That viewer is used in Firefox and project browser extensions. PDF.js renders annotations and supports adding a subset of annotation types, and it supports form filling; OCR is not provided. The project targets HTML5-compliant browsers and includes a legacy build for older browsers, although PDF feature support varies by browser and version. Prebuilt builds are available, with hosted copies listed through jsDelivr, cdnjs, and unpkg. Developers can clone and build it locally, but some browsers require a local web server instead of opening PDFs through file URLs. Cross-origin requests are blocked by default, so CORS or a server proxy may be needed. For large documents, rendering only visible pages can reduce memory use. PDF.js is licensed under Apache 2.0.