PdfKmp 1.0 — A Kotlin Multiplatform PDF Library for Android and iOS

Built specifically for Kotlin Multiplatform

PdfKmp is a KMP-first library. The DSL, the layout engine, and the document model all live in commonMain. Rendering dispatches to each OS's native PDF stack — android.graphics.pdf.PdfDocument on Android, UIGraphicsBeginPDFContextToData + Core Graphics on iOS. You write the document once and ship it to both stores.

If you only target Android, you can still use it as a plain Android library (pdfkmp-android artifact).

What's in the box

Document structure

• A Compose-style DSL: pdf { … }, page { … }, column, row, box, card
  


• Spacing, padding, weighted children, alignment


• Multi-page documents with automatic pagination

Text rendering

• Vector glyph paths — every character is a real PDF text operator, not a bitmap


• Single-style text(...) blocks and multi-style richText { span(...) } runs


• Font weights, italics, underline, strikethrough, letter spacing, line height, alignment

Tables

• Column weights and per-cell styling


• Header rows that repeat on every page


• Automatic page-break across long tables — no orphan rows

Decorations

• Backgrounds, rounded corners, borders, gradients


• Dividers, lines, circles, ellipses


• Bullet and numbered lists

Page-level features

• Headers and footers with access to current page number and total page count


• Watermarks


• Page numbers in any format you write

Hyperlinks

• 
  link(url) { … } emits real PDF link annotations — clickable in Adobe Reader, Preview, Chrome, and any spec-compliant viewer

Internationalisation

• Bundled Inter font, exposed as PdfFont.Default, identical bytes on both platforms


• Opt-in system fallbacks for non-Latin scripts: PdfFont.SystemCJK, PdfFont.SystemArabic, PdfFont.SystemPersian
  


• Custom fonts via registerFont(PdfFont.Custom(name, bytes)) for brand or licence-bound typefaces

Images and vector graphics

• Raster images (JPEG / PNG) embedded as-is for real photos


• Vector and SVG images stay vector — sharp at any zoom

Storage

• 
  StorageLocation.Documents / Downloads / Cache / AppFiles / Temp / Custom
  


• MediaStore on Android Q+ (no runtime permission needed)


• Sandboxed paths on iOS

Opt-in companion modules

• 
  pdfkmp-viewer — a Compose Multiplatform PDF viewer composable with topbar, share sheet, zoom, search, and text selection. Works as a standalone viewer for any PDF, not just PdfKmp-generated ones.


• 
  pdfkmp-compose-resources — bridges Compose Multiplatform DrawableResource references into the PdfKmp DSL.

The core pdfkmp artifact stays Compose-free. If you don't use Compose, you don't pay for it.

Why vector matters

Most "save to PDF" flows on mobile rasterise — they snapshot a View and embed that bitmap. PdfKmp is vector-only for everything except real photos. That gives you three things:

• 
  Small file size. A typical text-heavy invoice lands in the tens of kilobytes, not megabytes.


• 
  Crisp output at any zoom. Path operators are resolution-independent.


• 
  Searchable, accessible documents. Real text means Preview's ⌘F finds the order number, and screen readers can read the page.

Cross-platform parity is the contract

PdfKmp pins the bundled Inter font on both platforms so glyph metrics match exactly. Same DSL → same line breaks → same page splits → same final file. For non-Latin scripts that rely on system fonts, the fallback is named explicitly so any divergence is visible instead of silent.

If the output ever differs between Android and iOS on a document you care about, that's a bug — open an issue with the DSL snippet.

Stability signals

• 
  1.0 stable, follows SemVer — no breaking changes within the 1.x line


• 
  explicitApi() enforced — every public declaration is intentional


• 
  Apache 2.0 — drop-in for enterprise, no AGPL friction


• 
  R8-clean — no keep rules required


• 
  No third-party engines — output goes through the OS's native PDF stack

Links

https://github.com/ConaMobileDev/PdfKmp