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Mozilla PDF.js
What it is
Mozilla PDF.js is a web standards-based platform for parsing and rendering PDF files. Developers can use its display API to render documents and retrieve document information, or adapt its viewer layer to build a custom interface. The viewer is used in Firefox and the project’s browser extensions. PDF.js can display annotations and add a subset of annotation types, and it supports form filling; it does not provide OCR. The project targets HTML5-compliant browsers and provides a legacy build, though PDF feature support varies by browser and version. Prebuilt builds are available, along with hosted versions through jsDelivr, cdnjs, and unpkg. Developers can clone and build the project locally, but some browsers require a local web server to open PDFs. Cross-origin requests are blocked by default, so a CORS setup or server proxy may be needed. For large documents, rendering only visible pages can help reduce memory use. The project is community-driven, and it points users to GitHub issues and its Matrix room for technical help. PDF.js is free and licensed under Apache 2.0; its documentation uses CC BY-SA 2.5.
For and against
For
- Display API renders PDFs and retrieves document information
- Viewer layer can be adapted for custom interfaces
- Supports form filling and some annotation types
- Prebuilt builds and hosted CDN versions are available
- Free under the Apache 2.0 license
Against
- Does not provide OCR
- Cross-origin requests are blocked by default
- Some local PDF use requires a web server
- PDF feature support varies by browser and version
The verdict
PDF.js provides rendering and viewer components for browser-based PDF work, with options to adapt or self-host it. Developers should account for cross-origin restrictions, browser differences, and the lack of OCR.
Who it suits
PDF.js suits developers who want to embed PDF rendering or build a custom viewer. It may also interest contributors to a community-driven project.
Plans and prices
PDF.js
Open-source PDF parsing and rendering platform · Apache 2.0 license
Read 7 Oct 2026 · mozilla.github.io
On the record
- Annotations
- PDF.js renders annotations for viewing and supports adding a subset of annotation types.github.com · read 7 Oct 2026
- Annotation tools
- Yesmozilla.github.io · read 24 Sep 2026
- API
- The display layer exposes an API for rendering PDFs and retrieving document information.mozilla.github.io · read 7 Oct 2026
- Browser support
- The project aims to support HTML5-compliant browsers and provides a legacy build for older browsers; PDF feature support varies by browser and version.github.com · read 7 Oct 2026
- Cross-origin constraint
- PDF.js cannot make cross-origin requests by default; the FAQ describes CORS or a server proxy as possible approaches.github.com · read 7 Oct 2026
- Distribution
- Prebuilt builds are available, and the project lists jsDelivr, cdnjs, and unpkg as CDNs hosting PDF.js.mozilla.github.io · read 7 Oct 2026
- Form filling
- Yesmozilla.github.io · read 24 Sep 2026
- Integrations
- PDF.js is built into Firefox 19 and later, and the project provides a Chromium browser extension.github.com · read 7 Oct 2026
- Intended users
- The project describes itself as community-driven and invites contributors, while its library and viewer documentation gives developers ways to embed or build on PDF.js.github.com · read 7 Oct 2026
- Large documents
- The FAQ recommends rendering only visible pages to reduce memory use when working with many high-resolution pages.github.com · read 7 Oct 2026
- License
- PDF.js is licensed under Apache 2.0, and its documentation is licensed under CC BY-SA 2.5.mozilla.github.io · read 7 Oct 2026
- OCR support
- nonemozilla.github.io · read 24 Sep 2026
- Platform support
- webmozilla.github.io · read 24 Sep 2026
- Purpose
- PDF.js is a web standards-based platform for parsing and rendering PDF files.mozilla.github.io · read 7 Oct 2026
- Security reporting
- The project directs reports about the library or Firefox PDF Viewer to Bugzilla and reports about the Chrome extension to GitHub’s private vulnerability reporting form.github.com · read 7 Oct 2026
- Self hosting
- The project documents cloning and building PDF.js locally, and says a local web server is needed because some browsers disallow opening PDFs through file URLs.mozilla.github.io · read 7 Oct 2026
- Support
- The project points users to GitHub issues for technical problems and its Matrix room for questions or guidance.github.com · read 7 Oct 2026
- Viewer
- Its viewer layer provides the user interface used in Firefox and project browser extensions, and can be adapted to build a custom viewer.mozilla.github.io · read 7 Oct 2026
