Rust Crate

Installation

cargo add forme-pdf

The crate is published as forme-pdf on crates.io. The library name is forme:

use forme::{render_json, Document, Style, FormeError};

Quick start

use forme::{render_json, FormeError};

fn main() -> Result<(), FormeError> {
    let json = r#"{
        "pages": [{ "size": "A4" }],
        "children": [{
            "kind": "text",
            "content": "Hello from Forme!",
            "style": { "fontSize": 24, "margin": { "top": 72, "left": 72 } }
        }]
    }"#;

    let pdf_bytes = render_json(json)?;
    std::fs::write("hello.pdf", pdf_bytes).unwrap();
    Ok(())
}

API

Function	Description
`render(&Document)`	Render a `Document` struct to PDF bytes
`render_json(&str)`	Parse JSON and render to PDF
`render_with_layout(&Document)`	Render and return layout metadata
`render_json_with_layout(&str)`	Parse JSON, render, and return layout metadata
`render_template(&str, &str)`	Evaluate a template with data, then render
`render_template_with_layout(&str, &str)`	Evaluate a template with data, render, and return layout metadata

PDF operations

Function	Description
`merge_pdfs(&[&[u8]])`	Combine multiple PDFs into one
`certify_pdf(&[u8], &str, &str, ...)`	Apply a PKCS#7 digital signature to an existing PDF
`redact_pdf(&[u8], &[RedactionRegion])`	Redact regions from a PDF (removes underlying text)
`redact_text(&[u8], &[TextSearchRedaction])`	Find text by pattern and redact matching regions
`find_text_regions(&[u8], &[TextSearchPattern])`	Find text regions in a PDF without redacting

All functions return Result<Vec<u8>, FormeError> (or Result<(Vec<u8>, LayoutInfo), FormeError> for the _with_layout variants).

Working with the Document struct

For full control, build a Document directly instead of using JSON:

use forme::{Document, Node, NodeKind, PageConfig, PageSize, Style, Metadata, render};

let document = Document {
    children: vec![Node {
        kind: NodeKind::Text {
            content: "Hello from Forme!".to_string(),
        },
        style: Some(Style {
            font_size: Some(24.0),
            ..Default::default()
        }),
        children: vec![],
        ..Default::default()
    }],
    pages: vec![PageConfig {
        size: Some(PageSize::A4),
        ..Default::default()
    }],
    metadata: Metadata::default(),
    ..Default::default()
};

let pdf_bytes = render(&document)?;

Templates

Render dynamic documents by combining a template (with $ref, $each, $if expressions) and a data object:

use forme::render_template;

let template = r#"{
    "pages": [{ "size": "A4" }],
    "children": [{
        "kind": "text",
        "content": { "$ref": "greeting" },
        "style": { "fontSize": 24 }
    }]
}"#;

let data = r#"{ "greeting": "Hello, world!" }"#;

let pdf_bytes = render_template(template, data)?;

See the templates guide for the full expression language.

Layout metadata

The _with_layout variants return a LayoutInfo struct describing the position and dimensions of every element on every page. Useful for overlays, click-to-inspect, and testing:

use forme::render_json_with_layout;

let (pdf_bytes, layout) = render_json_with_layout(json)?;
println!("Pages: {}", layout.pages.len());
for page in &layout.pages {
    for element in &page.elements {
        println!("  {} at ({}, {})", element.id, element.x, element.y);
    }
}

Features

The engine supports:

Flexbox layout — row, column, wrap, grow/shrink, all alignment modes
CSS Grid — track sizing, auto/explicit placement, repeat() syntax
Text — OpenType shaping, Knuth-Plass line breaking, hyphenation (35+ languages), BiDi, per-character font fallback
Tables — automatic header repetition on page breaks
Images — JPEG, PNG, WebP
SVG — inline rendering (rect, circle, line, path, arc)
Charts — BarChart, LineChart, PieChart, AreaChart, DotPlot
QR codes & barcodes — Code128, Code39, EAN13, EAN8, Codabar
AcroForms — fillable PDF forms (TextField, Checkbox, Dropdown, RadioButton) with form flattening
Digital signatures — PKCS#7 detached signatures with X.509 certificates (PKCS#1 and PKCS#8 keys)
PDF/UA-1 — accessibility compliance with structure tree and artifact tagging
PDF/A — archival compliance (PDF/A-2b, PDF/A-2a)
PDF operations — merge, certify, redact, and text search on existing PDFs
Embedded data — attach JSON inside the PDF for round-tripping

WASM

The crate compiles to WebAssembly. Enable the wasm feature for wasm-bindgen support:

[dependencies]
forme-pdf = { version = "0.9", features = ["wasm"] }

This is how @formepdf/core works under the hood — the same engine, compiled to WASM and called from JavaScript.

Getting Started

Reference

API Reference

Concepts

Enterprise

SDKs

Guides

Changelog

Installation

Quick start

API

PDF operations

Working with the Document struct

Templates

Layout metadata

Features

WASM

​Installation

​Quick start

​API

​PDF operations

​Working with the Document struct

​Templates

​Layout metadata

​Features

​WASM

Installation

Quick start

API

PDF operations

Working with the Document struct

Templates

Layout metadata

Features

WASM