gpdf

Quickstart

Installation

go get github.com/gpdf-dev/gpdf

gpdf has zero external dependencies — it only uses the Go standard library.

Hello World

package main

import (
    "os"
    "github.com/gpdf-dev/gpdf/document"
    "github.com/gpdf-dev/gpdf/template"
)

func main() {
    doc := template.New(
        template.WithPageSize(document.A4),
        template.WithMargins(document.UniformEdges(document.Mm(20))),
    )

    page := doc.AddPage()
    page.AutoRow(func(r *template.RowBuilder) {
        r.Col(12, func(c *template.ColBuilder) {
            c.Text("Hello, World!", template.FontSize(24), template.Bold())
        })
    })

    data, _ := doc.Generate()
    os.WriteFile("hello.pdf", data, 0644)
}

┌─ A4 ──────────────────────────────────┐
│                                       │
│   Hello, World!    ← 24pt, Bold       │
│                                       │
│                                       │
└───────────────────────────────────────┘

Three Ways to Create PDFs

gpdf offers three approaches to PDF generation:

1. Builder API (Recommended)

The most common approach — programmatic control with a fluent builder pattern:

doc := template.New(template.WithPageSize(document.A4))
page := doc.AddPage()
page.AutoRow(func(r *template.RowBuilder) {
    r.Col(6, func(c *template.ColBuilder) {
        c.Text("Left column")
    })
    r.Col(6, func(c *template.ColBuilder) {
        c.Text("Right column")
    })
})
data, err := doc.Generate()

2. JSON Schema

Define documents declaratively in JSON — ideal for dynamic content and API-driven generation:

schema := []byte(`{
    "page": {"size": "A4", "margins": "20mm"},
    "body": [
        {"row": {"cols": [
            {"span": 12, "text": "Hello from JSON!", "style": {"size": 24, "bold": true}}
        ]}}
    ]
}`)

doc, err := template.FromJSON(schema, nil)
data, err := doc.Generate()

3. Reusable Components

Pre-built components for common business documents:

doc := template.Invoice(template.InvoiceData{
    Number:  "#INV-2026-001",
    Date:    "March 1, 2026",
    DueDate: "March 31, 2026",
    From:    template.InvoiceParty{Name: "ACME Corp", Address: []string{"123 Main St"}},
    To:      template.InvoiceParty{Name: "Client Inc", Address: []string{"456 Oak Ave"}},
    Items: []template.InvoiceItem{
        {Description: "Web Development", Quantity: "40 hrs", UnitPrice: 150.00, Amount: 6000.00},
    },
    TaxRate:  10,
    Currency: "$",
})
data, err := doc.Generate()

Output Methods

// Generate returns PDF as []byte
data, err := doc.Generate()

// Render writes PDF to any io.Writer
err := doc.Render(w)

Next Steps