flexpdf

flexpdf is a Rust library that renders a small, React-PDF-like XML syntax (or a Rust document model) into a PDF byte buffer. It aims for compatibility with react-pdf layouts and styling. It is built on a flexbox layout engine and is designed to be easy to embed into other Rust programs.

I have always been fascinated by how React-PDF makes it extremely easy to create PDF files (kudos to @diegomura and the authors) without first creating HTML + CSS and then converting that to a PDF file. React-PDF has awesome page-wrapping functionality and simple support for fonts. For me, it has been absolutely the most convenient way to create custom reports and various PDFs for my software.

The only problem with React-PDF is that it depends on the whole JavaScript/Node.js ecosystem. This library is trying to replicate the same great flexbox-based PDF creation idea, but natively. There are multiple test cases, and there is high 1:1 parity in the output PDFs. If you find any edge cases, please open a PR.

Features

• Render PDF from XML strings.
• Build documents directly in Rust without XML.
• Flexbox-based layout (via Taffy).
• Aiming for react-pdf compatibility.
• Embedded fonts (Google Fonts, local files, and PDF standard fonts).
• Images, links, annotations, and bookmarks.

Installation

[dependencies]
flexpdf = { path = "./flexpdf" }

TLS backend selection

By default, flexpdf uses reqwest with native TLS:

[dependencies]
flexpdf = "0.1.4"

To use rustls instead:

[dependencies]
flexpdf = { version = "0.1.4", default-features = false, features = ["tls-rustls"] }

Available TLS features:

• tls-native (default) -> enables reqwest/default-tls
• tls-rustls -> enables reqwest/rustls-tls

tls-native and tls-rustls are mutually exclusive.

Powered by

• Taffy for flexbox layout.
• Parley for text layout.
• skrifa and read-fonts for font parsing and metrics.
• quick-xml for XML parsing.
• reqwest for font downloads.

Usage (XML)

use flexpdf::render_xml;

let xml = r#"
<Document title="Quarterly Brief" author="Acme Studio" hyphenation="en">
  <Fonts>
    <Font family="Manrope" google="Manrope" />
  </Fonts>
  <Page size="A4">
    <View style="width: 100%; height: 100%; padding: 32; gap: 20; backgroundColor: #f8fafc; fontFamily: Manrope; color: #0f172a;">
      <View style="padding: 16; borderRadius: 12; backgroundColor: #2563eb; flexDirection: row; alignItems: center; justifyContent: space-between;">
        <Text style="color: #ffffff; fontSize: 18; fontWeight: 600;">Launch Brief</Text>
        <Text style="color: #ffffff; fontSize: 12;">Q2 2025</Text>
      </View>
      <View style="gap: 16; flexGrow: 1;">
        <Text style="fontSize: 16; fontWeight: 600;">Highlights</Text>
        <View style="flexDirection: row; gap: 12;">
          <View style="flexGrow: 1; padding: 14; borderRadius: 10; backgroundColor: #dbeafe;">
            <Text style="fontSize: 10; color: #64748b;">Signups</Text>
            <Text style="fontSize: 18; fontWeight: 700;">3,482</Text>
          </View>
          <View style="flexGrow: 1; padding: 14; borderRadius: 10; backgroundColor: #dcfce7;">
            <Text style="fontSize: 10; color: #64748b;">Retention</Text>
            <Text style="fontSize: 18; fontWeight: 700;">68%</Text>
          </View>
          <View style="flexGrow: 1; padding: 14; borderRadius: 10; backgroundColor: #fef3c7;">
            <Text style="fontSize: 10; color: #64748b;">NPS</Text>
            <Text style="fontSize: 18; fontWeight: 700;">54</Text>
          </View>
        </View>
        <View style="padding: 16; borderRadius: 10; backgroundColor: #e2e8f0;">
          <Text style="fontWeight: 600;">Next steps</Text>
          <Text style="color: #64748b;">Finalize onboarding and ship the analytics refresh.</Text>
        </View>
      </View>
      <View style="flexDirection: row; justifyContent: space-between; alignItems: center;">
        <Text style="color: #64748b; fontSize: 10;">Acme Studio • Internal</Text>
        <Text style="color: #64748b; fontSize: 10;">Page {pageNumber} of {totalPages}</Text>
      </View>
    </View>
  </Page>
</Document>
"#;

let pdf_bytes = render_xml(xml)?;
std::fs::write("styled.pdf", pdf_bytes)?;
# Ok::<(), flexpdf::Error>(())

Usage (Rust model)

use flexpdf::builder::{document, text, view};
use flexpdf::{render_document, PageSize, Style};

let doc = document()
    .title("Hello")
    .page_with(PageSize::A4, |page| {
        page.child(
            view()
                .style(Style {
                    padding: Some(24.0),
                    ..Style::default()
                })
                .children([text("Hello from Rust"), text("Second line")]),
        )
    })
    .build();

let pdf_bytes = render_document(&doc)?;
std::fs::write("hello.pdf", pdf_bytes)?;
# Ok::<(), flexpdf::Error>(())

Import existing PDF pages

You can include imported pages anywhere in the document flow:

use flexpdf::builder::{document, text, view};
use flexpdf::{render_document, PageSize};

let input_bytes = std::fs::read("input.pdf")?;

let doc = document()
    .page_with(PageSize::A4, |page| page.child(view().child(text("Dynamic A"))))
    .import_pdf_bytes_pages(input_bytes, [1, 2])
    .page_with(PageSize::A4, |page| page.child(view().child(text("Dynamic B"))))
    .import_pdf_pages("appendix.pdf", [1])
    .page_with(PageSize::A4, |page| page.child(view().child(text("Dynamic C"))))
    .build();

let pdf_bytes = render_document(&doc)?;
std::fs::write("output.pdf", pdf_bytes)?;
# Ok::<(), flexpdf::Error>(())

XML supports the same flow with <ImportPdf /> as a sibling of <Page>:

<Document>
  <Page size="A4"><Text>Dynamic A</Text></Page>
  <ImportPdf src="input.pdf" pages="1,2" />
  <Page size="A4"><Text>Dynamic B</Text></Page>
  <ImportPdf src="appendix.pdf" pages="1-2,4" />
  <Page size="A4"><Text>Dynamic C</Text></Page>
</Document>

pages accepts comma-separated page numbers and ranges (1,3-5). Use import_pdf_pages(path, pages) for file paths and import_pdf_bytes_pages(bytes, pages) for in-memory Rust Vec<u8> data. Native import supports both classic xref-table PDFs and xref-stream/object-stream PDFs.

Library entry points

• render_xml(xml: &str) -> Result<Vec<u8>, Error>
• parse_xml(xml: &str) -> Result<Document, Error>
• render_document(doc: &Document) -> Result<Vec<u8>, Error>

CLI (optional)

A small CLI binary is included for development:

cargo run --manifest-path flexpdf/Cargo.toml --bin flexpdf -- path/to/input.xml path/to/output.pdf

Documentation

You can check react-pdf components for the component API reference. Hyphenation configuration is done differently in this library (we use the hyphenation Rust library). You can add: or Also in this library we have new element.

License

This project is dual-licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT License (LICENSE-MIT)

The AFM font metric data in assets/pdfkit/afm is derived from PDFKit and is licensed under the MIT license in assets/pdfkit/LICENSE.