Best Free PDF SDK 2026
If you are looking for the best free PDF SDK in 2026, focus on open source quality, engine flexibility, and the full reader workflow. This guide explains what to evaluate and where Papyrus fits.
What it is: an evergreen checklist for picking a free PDF SDK.
Who it's for: product teams comparing open source options.
When to use: you need a reader SDK, not just a renderer.
When not to use: you only need basic PDF rendering.
What "free" should mean in 2026
- A clear open source license (MIT, Apache-2.0, GPL) with no hidden usage caps.
- Transparent maintenance and a public roadmap.
- No paywall for basic features like search, text selection, or outlines.
Papyrus is MIT licensed and open source, which makes it safe to evaluate and ship in commercial products.
What to look for in a PDF SDK
- Engine quality: PDF.js, PDFium, or native engines with good rendering and text layers.
- UI layer: Reusable components for viewer, toolbar, outline, and search.
- Annotations: Highlights, notes, and reliable selection state.
- Search and navigation: Full-text search, outline, and page control.
- Multi-format support: PDF plus EPUB and TXT if your product needs it.
- Web and mobile parity: React on web and React Native on mobile.
Shortlist categories
1) Engine-only stacks
If you only need a renderer, an engine like PDF.js may be enough. You will still need to build UI, state, and annotations yourself.
2) Modular open source SDKs
This is where Papyrus fits: a shared core, pluggable engines, and UI kits for React and React Native. It is designed for building document readers, not just rendering pages.
3) Commercial SDKs with free tiers
Some vendors offer a limited free tier. These can be useful but often restrict annotations or advanced search.
Recommended free PDF SDKs in 2026
- Papyrus: best open source option for reader UX on web and React Native. See the Open Source PDF SDK.
- PDF.js: solid engine-only renderer if you are building all UI and state yourself.
- Commercial free tiers: useful for evaluation, but typically limited in features or usage.
Why Papyrus is a strong option
- Open source PDF SDK with MIT license.
- Engine-agnostic core that works with PDF.js and native engines.
- UI components for document readers (viewer, sidebars, topbar).
- Event-driven state for annotations, search, and selection.
- Multi-format support: PDF, EPUB, and TXT.
Quick checklist
Use this to compare candidates quickly:
- Open source license with clear terms
- Web and mobile support
- Search + outline built in
- Annotations and selection events
- Theming and UI control
- Active docs and examples