Go

Last updated: 2026-06-29

The rustpdf-go module wraps the rust-pdf C core with idiomatic Go types over cgo. It covers the whole product surface: vector graphics, embedded/subset fonts & Unicode text, paragraphs, images, PDF/A (1b–3a + A-4/4e/4f), tagged/accessible output, attachments, AcroForm fields, manipulation, text extraction, encryption and digital signatures. The native library is statically linked from a prebuilt archive bundled per platform, so go get + go build just works — no separate native install.

Installation

Add the module with go get. A prebuilt static libpdf_ffi.a for your platform ships inside the module (under lib/<os>_<arch>/), so there is nothing else to install or compile.

go get github.com/rustpdf/rustpdf-go@latest

Requires Go 1.21+ and a C compiler on PATH (cgo, enabled by default). Supported platforms: darwin/arm64, darwin/amd64, linux/amd64, linux/arm64, windows/amd64. Import it (the package is named rustpdf):

import rustpdf "github.com/rustpdf/rustpdf-go"

fmt.Println(rustpdf.Version())   // native library version

Quick start

A one-page document with a filled rectangle, saved to disk. Errors are elided with _ for brevity — see Error handling for the real pattern:

package main

import rustpdf "github.com/rustpdf/rustpdf-go"

func main() {
	doc, _ := rustpdf.New()       // A4 by default
	defer doc.Close()

	_ = doc.AddPage()
	_ = doc.SetFillRGB(0.86, 0.20, 0.18)
	_ = doc.Rect(72, 640, 200, 120)   // x, y, width, height (points)
	_ = doc.Fill()
	_ = doc.Save("out.pdf")
}

Get the bytes instead of writing a file with ToBytes:

doc, _ := rustpdf.New()
defer doc.Close()
font, _ := doc.AddFontFile("Roboto-Regular.ttf")
_ = doc.AddPage()
_ = doc.SetFillRGB(0.1, 0.1, 0.12)
_ = doc.Rect(0, 800, 595, 42)
_ = doc.Fill()
_ = doc.ShowText(font, 24, 72, 740, "Olá, açúcar — café", 0)
data, _ := doc.ToBytes()           // []byte instead of a file

cgo & deployment

The binding links the native library statically, so a built binary carries it — there is no shared library to ship alongside.

• Build host needs a C toolchain. cgo is on by default (CGO_ENABLED=1); install a C compiler (Xcode CLT on macOS, build-essential on Linux, MinGW-w64 on Windows).
• Cross-compilation needs a cross C toolchain for the target (set CC), because cgo invokes the platform C compiler. Pure GOOS/GOARCH cross-builds without a cross-CC won't link.
• The bundled archive is per-platform. Building for a target outside the supported set above has no archive to link against.
• Containers: build inside an image that has the C toolchain; the resulting binary needs only the usual system libs at runtime (no rust-pdf shared object).

Licensing & activation

Basic generation (everything above) is always free. The corporate features (PDF/A, digital signatures/PAdES, encryption, accessibility) require an active license token. Without one, those calls return an *Error and produce no output.

Activation needs no rebuild. Easiest is an environment variable, auto-activated the first time a corporate feature is used:

export RUSTPDF_LICENSE="010f0000…"           # the token we email you
# or point at a file:
export RUSTPDF_LICENSE_FILE=/etc/rustpdf/license.txt

Or activate explicitly in code:

if err := rustpdf.ActivateLicense(token); err != nil {
	log.Fatal(err)   // forged / expired / malformed
}

Coordinate system

• Units are points (1 pt = 1/72 inch). A4 is 595 × 842, US Letter 612 × 792.
• The origin (0, 0) is the bottom-left corner; y grows upward.
• For text, (x, y) is the baseline of the first glyph.
• Drawing/text always targets the most recently added page.

Goroutines & concurrency

Every native call is synchronous and the core is Send but not Sync: a single handle must never be touched by two goroutines at once.

• Documents are independent. Each Document/EditableDoc shares no state, so building several in parallel goroutines is fine — one handle per goroutine.
• Don't share a live handle across goroutines; give each its own (or guard it with a mutex).
• Errors are per-thread. The native last-error is thread-local, so a failure in one goroutine never clobbers another's, and the message surfaces on the calling side.
• License is process-global. ActivateLicense (or the env var) applies everywhere; activate once at startup.

var wg sync.WaitGroup
for i := 0; i < 4; i++ {
	wg.Add(1)
	go func(n int) {
		defer wg.Done()
		doc, _ := rustpdf.New()      // one document per goroutine
		defer doc.Close()
		_ = doc.AddPage()
		_ = doc.SetFillRGB(0.1, 0.1, 0.12)
		_ = doc.Rect(72, 700, 200, 80)
		_ = doc.Fill()
		_ = doc.Save(fmt.Sprintf("out-%d.pdf", n))
	}(i)
}
wg.Wait()

Authoring: create & save

Creates an empty document (A4 default page size). Call Close() to free the native handle.

Pages & vector graphics

Graphics state and path operators mirror PDF's content-stream model. Colors are RGB in 0.0–1.0.

doc, _ := rustpdf.New()
defer doc.Close()
_ = doc.AddPage()
_ = doc.SetStrokeRGB(0.10, 0.45, 0.90)
_ = doc.SetLineWidth(3)
_ = doc.Rect(72, 600, 300, 160)
_ = doc.Stroke()
_ = doc.SetFillRGB(0.95, 0.77, 0.06)
_ = doc.Rect(120, 640, 120, 80)
_ = doc.Fill()
_ = doc.Save("shapes.pdf")

Fonts & text

Fonts are embedded and subsetted, with HarfBuzz-quality shaping, kerning and full Unicode (Type0/CIDFontType2 with ToUnicode, so text extracts and copies correctly, provided the embedded font covers those characters). Register a font once, then reference it by its integer id.

headingLevel (1–6) tags the run as H1–H6 in an accessible document (see Accessibility); pass 0 for ordinary text.

doc, _ := rustpdf.New()
defer doc.Close()
regular, _ := doc.AddFontFile("Roboto-Regular.ttf")
// …or from bytes you already have in memory:
// data, _ := os.ReadFile("Roboto-Regular.ttf"); regular, _ := doc.AddFont(data)

_ = doc.AddPage()
_ = doc.ShowText(regular, 28, 72, 760, "Invoice #1024", 0)
_ = doc.ShowText(regular, 12, 72, 720, "日本語 · Ελληνικά · العربية", 0)
_ = doc.Save("text.pdf")

Paragraphs

The paragraph layer wraps, aligns and justifies text inside a fixed width (greedy line breaking using shaped glyph widths).

intro := "A long paragraph that wraps to the given width and is justified " +
	"automatically; extra space is distributed between words."

doc, _ := rustpdf.New()
defer doc.Close()
f, _ := doc.AddFontFile("Roboto-Regular.ttf")
_ = doc.AddPage()
_ = doc.Paragraph(f, 12, 72, 700, 451, intro, rustpdf.AlignJustify)
_ = doc.Save("paragraph.pdf")

See the Align enum for the alignment options.

Images

JPEGs are embedded verbatim (DCTDecode, no re-encode). PNGs are decoded and re-encoded (FlateDecode); alpha becomes an /SMask, palette becomes an Indexed color space. Register an image once, draw it many times.

doc, _ := rustpdf.New()
defer doc.Close()
logo, _ := doc.AddImageFile("logo.png")
_ = doc.AddPage()
_ = doc.DrawImage(logo, 72, 680, 160, 90)
_ = doc.Save("with_image.pdf")

PDF/A licensed

Produce archival-grade output. Pdfa() defaults to A-2b; PdfaLevel(level) selects a specific PdfaLevel. An embedded sRGB ICC profile, output intent, XMP metadata and document /ID are added automatically; A-1b also forces PDF 1.4 and emits a /CIDSet, and A-4 (ISO 19005-4) is based on PDF 2.0.

doc, _ := rustpdf.New()
defer doc.Close()
_ = doc.PdfaLevel(rustpdf.A2b)
_ = doc.SetInfo(rustpdf.Info{Title: "Q3 Report", Author: "Acme Inc."})
f, _ := doc.AddFontFile("Roboto-Regular.ttf")
_ = doc.AddPage()
_ = doc.ShowText(f, 20, 72, 760, "Archival report", 0)
if err := doc.Save("report_pdfa.pdf"); err != nil {
	log.Fatal(err)   // *Error without a license granting PDF/A
}

Accessibility (Tagged PDF / PDF/UA) licensed

Tagged() builds a logical structure tree (PDF/UA-1). Combine with PdfaLevel(rustpdf.A2a) for archival and accessible output. Use headingLevel on ShowText for H1–H6, and Figure(..., alt) for described images.

doc, _ := rustpdf.New()
defer doc.Close()
_ = doc.PdfaLevel(rustpdf.A2a)
_ = doc.Tagged()
_ = doc.SetInfo(rustpdf.Info{Title: "Accessible report"})
f, _ := doc.AddFontFile("Roboto-Regular.ttf")
_ = doc.AddPage()
_ = doc.ShowText(f, 26, 72, 760, "Annual report", 1)   // H1
_ = doc.ShowText(f, 14, 72, 720, "Overview", 2)         // H2
_ = doc.ShowText(f, 11, 72, 690, "Body paragraph of the section…", 0)
chart, _ := doc.AddImageFile("chart.png")
_ = doc.Figure(chart, 72, 520, 300, 150, "Revenue grew 18% year over year")
_ = doc.Save("accessible.pdf")

Attachments (PDF/A-3) licensed

PDF/A-3 allows embedding arbitrary source files (e.g. the XML behind an e-invoice). Each attachment carries a MIME type and an AFRelationship.

xml, _ := os.ReadFile("invoice.xml")

doc, _ := rustpdf.New()
defer doc.Close()
_ = doc.PdfaLevel(rustpdf.A3b)
_ = doc.SetInfo(rustpdf.Info{Title: "E-invoice 1024"})
f, _ := doc.AddFontFile("Roboto-Regular.ttf")
_ = doc.AddPage()
_ = doc.ShowText(f, 18, 72, 760, "Invoice 1024", 0)
_ = doc.AttachFile("invoice.xml", "text/xml", xml,
	rustpdf.RelSource, "Structured invoice data")
_ = doc.Save("einvoice.pdf")

ZUGFeRD / Factur-X e-invoices licensed

Turn the document into a ZUGFeRD / Factur-X electronic invoice: the embedded XML (the Cross-Industry Invoice) is attached as factur-x.xml, the file is marked PDF/A-3, and the Factur-X identification is written into the XMP metadata. The visible PDF is the human-readable invoice; the embedded XML is its machine-readable twin. Validates as PDF/A-3 + Factur-X under veraPDF.

xml, _ := os.ReadFile("factur-x.xml")        // your Cross-Industry Invoice XML

doc, _ := rustpdf.New()
defer doc.Close()
_ = doc.SetInfo(rustpdf.Info{Title: "Invoice INV-2026-001"})
f, _ := doc.AddFontFile("Roboto-Regular.ttf")
_ = doc.AddPage()
_ = doc.ShowText(f, 18, 72, 760, "Invoice INV-2026-001", 0)
_ = doc.Facturx(xml, rustpdf.FacturxEN16931)
_ = doc.Save("einvoice.pdf")        // PDF/A-3 + Factur-X; needs a PDF/A license

See the FacturxProfile enum for the conformance levels (FacturxMinimum through FacturxExtended).

AcroForm fields

Build interactive forms with generated appearance streams (no NeedAppearances). Rectangles are [4]float64{x0, y0, x1, y1}; page is a 0-based page index. Dotted names ("a.b.c") create hierarchical fields.

doc, _ := rustpdf.New()
defer doc.Close()
_ = doc.AddPage()
_ = doc.TextField("applicant.name", 0, [4]float64{72, 700, 320, 720}, "", 0)
_ = doc.Checkbox("agree", 0, [4]float64{72, 660, 88, 676}, false)
_ = doc.Dropdown("plan", 0, [4]float64{72, 620, 240, 640},
	[]string{"Starter", "Pro", "Enterprise"}, 1, 0)
_ = doc.RadioGroup("billing", 0, []rustpdf.RadioButton{
	{Rect: [4]float64{72, 580, 88, 596}, Export: "monthly"},
	{Rect: [4]float64{140, 580, 156, 596}, Export: "annual"},
}, 1)
_ = doc.Save("form.pdf")

Fill and flatten fields later with EditableDoc.

Hyperlinks free

Add clickable link rectangles to the current page: a web link opens a URL; an internal link jumps to another page (optionally scrolling so a given top y-coordinate sits at the top of the view).

doc, _ := rustpdf.New()
defer doc.Close()
f, _ := doc.AddFontFile("Roboto-Regular.ttf")
_ = doc.AddPage()
_ = doc.ShowText(f, 14, 72, 760, "Visit rustpdf.dev (see page 2)", 0)
_ = doc.LinkURI([4]float64{72, 756, 320, 776}, "https://rustpdf.dev/")   // web link
top := 800.0
_ = doc.LinkToPage([4]float64{330, 756, 430, 776}, 1, &top)              // jump to page 2
_ = doc.AddPage()
_ = doc.Save("links.pdf")

Rectangles are [4]float64{x0, y0, x1, y1} in points; pageIndex is 0-based. Pass nil for top to keep the current scroll position.

Bookmarks / outline free

Build a navigable document outline. A Bookmark has a title, a target page and an optional Top; nest children with .Child(...) (or by setting the Children slice). A document with bookmarks opens with the outline pane shown.

doc, _ := rustpdf.New()
defer doc.Close()
_, _ = doc.AddFontFile("Roboto-Regular.ttf")
for i := 0; i < 3; i++ {
	_ = doc.AddPage()
}
top := 820.0
_ = doc.AddBookmark(
	rustpdf.Bookmark{Title: "Chapter 1", Page: 0, Top: &top}.
		Child(rustpdf.Bookmark{Title: "Section 1.1", Page: 1}).
		Child(rustpdf.Bookmark{Title: "Section 1.2", Page: 2}))
_ = doc.AddBookmark(rustpdf.Bookmark{Title: "Chapter 2", Page: 2})
_ = doc.Save("outline.pdf")

Metadata

Sets the document information dictionary (and, for PDF/A, the matching XMP). Set only the fields you need.

_ = doc.SetInfo(rustpdf.Info{
	Title:    "Q3 Report",
	Author:   "Acme Inc.",
	Subject:  "Quarterly results",
	Keywords: "finance, q3",
})

Manipulation: load an existing PDF

EditableDoc parses an existing document (classic & xref streams, object streams, all standard filters, RC4/AES decryption) into an editable model. Pages are a flat list; the page tree is rebuilt on output.

data, _ := os.ReadFile("in.pdf")
ed, _ := rustpdf.Load(data)
defer ed.Close()
fmt.Println(ed.PageCount())

To open a password-protected document, pass the user or owner password. The wrong password returns an *Error rather than loading garbage.

data, _ := os.ReadFile("secured.pdf")
ed, err := rustpdf.LoadWithPassword(data, "owner-secret")
if err != nil {
	log.Fatal(err)   // *Error on a wrong password
}
defer ed.Close()
fmt.Println(ed.PageCount())

Pages: merge, split, reorder, rotate

ad, _ := os.ReadFile("a.pdf")
bd, _ := os.ReadFile("b.pdf")
a, _ := rustpdf.Load(ad)
defer a.Close()
b, _ := rustpdf.Load(bd)
_ = a.Merge(b)                 // a now has a's pages followed by b's
b.Close()
_ = a.RotatePage(0, 90)
_ = a.Save("merged.pdf")

sub, _ := a.ExtractPages([]int{0, 2})   // pages 1 and 3
defer sub.Close()
_ = sub.Save("subset.pdf")

Metadata, overlay & form fill

data, _ := os.ReadFile("form.pdf")
ed, _ := rustpdf.Load(data)
defer ed.Close()
_ = ed.SetInfo("Title", "Filled form")
found, _ := ed.FillTextField("applicant.name", "Jane Doe")
title, _ := ed.GetInfo("Title")
fmt.Println("filled:", found, "| title:", title)
_ = ed.Save("filled.pdf")

Form fill & flatten free

Fill the fields of an existing AcroForm and (optionally) flatten them: filling generates a fresh appearance stream (no NeedAppearances), and flattening bakes every widget's appearance into the page content and removes the interactive form entirely. The setter methods return (bool, error): the bool reports whether a field with that name was found.

data, _ := os.ReadFile("form.pdf")
ed, _ := rustpdf.Load(data)
defer ed.Close()
names, _ := ed.FieldNames()                 // ["applicant.name", "agree", "plan", ...]
fmt.Println(names)
_, _ = ed.FillTextField("applicant.name", "Jane Doe")
_, _ = ed.SetCheckbox("agree", true)
_, _ = ed.SetRadio("billing", "annual")
_, _ = ed.SetChoice("plan", "Pro")
_ = ed.FlattenForms()                       // optional: make it non-editable
_ = ed.Save("filled.pdf")

Watermarks free

Stamp a diagonal text watermark or a centered image watermark across every page, drawn semi-transparently over the existing content. Text uses the standard Helvetica font, so keep it to WinAnsi (Latin-1) for stamps like "CONFIDENTIAL". The color is RGB in 0.0..1.0, opacity in 0.0..1.0, and rotation is in degrees.

data, _ := os.ReadFile("report.pdf")
ed, _ := rustpdf.Load(data)
defer ed.Close()
_ = ed.WatermarkText("CONFIDENTIAL", 64, 0.5, 0.5, 0.5, 0.25, 45)
_ = ed.Save("stamped.pdf")

Redaction licensed

True redaction: the text and graphics whose origin falls inside a rectangle are removed from the content stream (not just covered), so the data is gone from the file and is no longer extractable. Opaque black boxes are then painted over the regions. Returns whether the target page existed.

data, _ := os.ReadFile("statement.pdf")
ed, _ := rustpdf.Load(data)
defer ed.Close()
// rects = list of [4]float64{x0, y0, x1, y1} on that page
ok, err := ed.Redact(0, [][4]float64{
	{60, 590, 400, 620},
	{60, 540, 400, 570},
})
if err != nil {
	log.Fatal(err)   // *Error without a license granting redaction
}
fmt.Println("page found:", ok)
_ = ed.Save("redacted.pdf")

Convert to PDF/A licensed

Convert an existing PDF to archival PDF/A (a basic profile: A-1b, A-2b or A-3b). An sRGB output intent, PDF/A XMP metadata (synced with /Info) and a document /ID are added. Fails if any font is not embedded (PDF/A requires every font embedded) or if a level-A profile is requested.

data, _ := os.ReadFile("in.pdf")
ed, _ := rustpdf.Load(data)
defer ed.Close()
if err := ed.ConvertToPdfa(rustpdf.A2b); err != nil {
	log.Fatal(err)   // *Error if fonts aren't embedded
}
_ = ed.Save("archival.pdf")     // veraPDF: PDF/A-2b compliant

Optimize & compact

data, _ := os.ReadFile("big.pdf")
ed, _ := rustpdf.Load(data)
defer ed.Close()
_ = ed.Optimize()
_ = ed.Compact(true)
_ = ed.Save("small.pdf")

Encryption licensed

Apply standard-handler encryption at output. AES-256 (V5/R6) uses OS-CSPRNG keys/IVs.

data, _ := os.ReadFile("in.pdf")
ed, _ := rustpdf.Load(data)
defer ed.Close()
if err := ed.Encrypt(rustpdf.AES256, "", "owner-secret", true); err != nil {
	log.Fatal(err)   // *Error without an Encryption license
}
_ = ed.Save("secured.pdf")

See the Encryption enum for RC4 / AES-128 / AES-256.

Output & incremental update

original, _ := os.ReadFile("in.pdf")
ed, _ := rustpdf.Load(original)
defer ed.Close()
_ = ed.SetInfo("Subject", "reviewed")
incremental, _ := ed.ToBytesIncremental(original)   // original bytes preserved verbatim
_ = os.WriteFile("reviewed.pdf", incremental, 0o644)

Digital signatures licensed

Sign a PDF with a PKCS#7 detached signature via an incremental update (the original bytes are preserved). Keys and certificates are passed as DER bytes. PAdES: true switches to PAdES-B-B.

pdf, _ := os.ReadFile("contract.pdf")
keyDER, _ := os.ReadFile("signing-key.pkcs8.der")   // PKCS#8 private key (DER)
certDER, _ := os.ReadFile("signing-cert.der")       // X.509 certificate (DER)

signed, err := rustpdf.Sign(pdf, keyDER, certDER, rustpdf.SignOptions{
	Reason: "Approved", Location: "New York",
	Name: "Jane Doe", PAdES: true,
})
if err != nil {
	log.Fatal(err)
}
_ = os.WriteFile("contract.signed.pdf", signed, 0o644)
// Verify in a shell: pdfsig contract.signed.pdf  →  "Signature is Valid."

Timestamp & DSS (PAdES LTV) licensed

Build long-term-validation signatures offline. AddDss appends a Document Security Store (/DSS with certs/CRLs, PAdES-B-LT); Timestamp appends an RFC 3161 document timestamp (/DocTimeStamp, PAdES-B-LTA).

signed, _ := os.ReadFile("contract.signed.pdf")

// B-LT: embed validation material (caller supplies DER certs/CRLs)
lt, _ := rustpdf.AddDss(signed, [][]byte{certDER}, [][]byte{crlDER})

// B-LTA: add a document timestamp signed by a TSA key/cert (date "" = now)
lta, _ := rustpdf.Timestamp(lt, tsaKeyDER, tsaCertDER, "")
_ = os.WriteFile("contract.lta.pdf", lta, 0o644)

Validate signatures licensed

Validate every signature in a PDF: each report recomputes the /ByteRange digest, parses the CMS, and checks that the cryptographic signature is valid, that the messageDigest matches the covered bytes, and whether the signature covers the whole document.

Each SignatureReport has FieldName and Signer (both *string, and nil when absent, so dereference only after a nil check as the example does for Signer), plus SubFilter, CoversWholeDocument, DigestValid, SignatureValid, IsValid and ByteRange. An empty slice means the document is unsigned. Signature validation is a licensed feature: this call requires an active license (signatures) even when the document is unsigned — it is not available on the free tier.

data, _ := os.ReadFile("contract.signed.pdf")
reports, _ := rustpdf.VerifySignatures(data)
for _, sig := range reports {
	signer := "(unknown)"
	if sig.Signer != nil {
		signer = *sig.Signer
	}
	fmt.Printf("%s valid:%v covers whole doc:%v\n",
		signer, sig.IsValid, sig.CoversWholeDocument)
}

Text & image extraction

Extract a document's text, mapping shown glyph codes back to Unicode through each font's ToUnicode map, with space/line inference. Raster images can be pulled out too: JPEGs are written verbatim as .jpg, everything else as .png. The output directory is created automatically if it does not already exist.

data, _ := os.ReadFile("report.pdf")
text, _ := rustpdf.ExtractText(data)
fmt.Println(text)

n, _ := rustpdf.ExtractImagesToDir(data, "out_images/")   // returns how many were written
fmt.Printf("wrote %d image(s)\n", n)

Render a page to an image licensed

Rasterize a page to a PNG image. A native Rust renderer (built on tiny-skia, with no headless browser) interprets the page content stream, painting real glyph outlines, vector graphics, images, color and transparency. Page rendering is a Pro feature; page_count is free.

data, _ := os.ReadFile("report.pdf")
n, _ := rustpdf.PageCount(data)
fmt.Printf("%d page(s)\n", n)
png, _ := rustpdf.RenderPageToPng(data, 0, 150.0)
os.WriteFile("page1.png", png, 0o644)

Enums

PdfaLevel

Align

AFRelationship

Encryption

FacturxProfile

Error handling

Every failing native call returns an *Error carrying the Status (PdfStatus) code and the library's last-error message. License failures (missing/expired/forged token, or a feature the token doesn't grant) surface here too. Token activation failures carry the dedicated license status code (12); a gated build, sign or encrypt call instead reports that operation’s own status, with the same “requires a valid license” message. ToBytes reports Serialize = 4 and Sign reports 10. Note that Save (which writes a file) maps every failure, including a gated feature, to IO = 3 rather than 4, so match on the message rather than assuming 4 for serialization errors. Use errors.As to inspect the code.

import "errors"

doc, _ := rustpdf.New()
defer doc.Close()
_ = doc.Pdfa()
_ = doc.SetInfo(rustpdf.Info{Title: "x"})
_ = doc.AddPage()
if err := doc.Save("out.pdf"); err != nil {
	var pe *rustpdf.Error
	if errors.As(err, &pe) {
		fmt.Printf("failed: status=%d: %s\n", pe.Status, pe.Message)
		// e.g. status=3 (IO): feature 'pdfa' requires a valid license
			// (doc.ToBytes() would report status=4, Serialize)
	}
}

Utilities