go-zpl

A native Go library for generating, parsing, and rendering ZPL (Zebra Programming Language) commands for thermal label printers.

Privacy

Everything runs locally - there are no servers or external API calls. The library runs in your application, the CLI processes files on your machine, and the web demo uses WebAssembly to render entirely in-browser.

Features

• Native ZPL generation without external dependencies
• No reliance on web services (Labelary, etc.)
• Builder pattern for constructing labels
• Implements standard Go interfaces (fmt.Stringer, io.WriterTo, encoding.TextMarshaler)
• Support for common ZPL elements:
  • Text fields with fonts and positioning
  • Barcodes (Code 128, Code 39, QR codes, DataMatrix, PDF417, MaxiCode, EAN-13, UPC-A, etc.)
  • Graphics (boxes, circles, ellipses, diagonal lines)
  • Field blocks and text formatting
• ZPL parsing - Parse existing ZPL strings into Label objects
• Multi-page labels - Parse and render ZPL with multiple labels (e.g., USPS APO continuation sheets)
• Local rendering - Render labels to PNG images without external services

Installation

Library

go get github.com/StirlingMarketingGroup/go-zpl

CLI Tool

go install github.com/StirlingMarketingGroup/go-zpl/cmd/zplrender@latest

Rust (crates.io)

[dependencies]
zpl-rs = "0.1"

let png_bytes = zpl_rs::render("^XA^FO50,50^A0N,30,30^FDHello!^FS^XZ")?;

C/C++/Other Languages

Pre-built shared libraries (libzpl) are available for FFI integration. See releases for downloads and cmd/libzpl for documentation.

CLI Usage

# Convert ZPL file to PNG
zplrender label.zpl

# Specify output filename
zplrender -o output.png label.zpl

# Render at 300 DPI
zplrender -dpi 300 label.zpl

# Output as JPEG
zplrender -format jpeg label.zpl

# Read from stdin
cat label.zpl | zplrender -o output.png

# Show all options
zplrender -help

Quick Start

package main

import (
    "fmt"

    "github.com/StirlingMarketingGroup/go-zpl"
)

func main() {
    label := zpl.NewLabel().
        SetDPI(zpl.DPI203).
        SetSize(4, 6, zpl.UnitInches).
        TextField(50, 50, zpl.Font0, 30, 30, "Hello, World!").
        Code128(50, 150, "123456789", 100).
        QRCode(50, 300, "https://example.com", 5)

    fmt.Println(label)
}

Output:

^XA
^PW812
^LL1218
^FO50,50
^A0N,30,30
^FDHello, World!^FS
^FO50,150
^BCN,100,Y,N,N,N^FD123456789^FS
^FO50,300
^BQN,2,5^FDMA,https://example.com^FS
^XZ

API Overview

Creating Labels

// Create a new label with builder pattern
label := zpl.NewLabel().
    SetDPI(zpl.DPI203).           // Set printer DPI (203, 300, or 600)
    SetSize(4, 6, zpl.UnitInches) // Set label size

Adding Text

// Simple text field
label.TextField(x, y, zpl.Font0, height, width, "Your text")

// Text block with wrapping
label.TextBlock(x, y, zpl.Font0, height, width, blockWidth, maxLines, zpl.JustifyCenter, "Long text...")

// Using unit conversion
label.TextFieldAt(0.5, 0.5, zpl.UnitInches, zpl.Font0, 30, 30, "Text")

Adding Barcodes

// Code 128
label.Code128(x, y, "data", height)

// Code 39
label.Code39(x, y, "DATA", height)

// QR Code
label.QRCode(x, y, "data", magnification)

// DataMatrix
label.DataMatrix(x, y, "data", moduleSize)

// PDF417
label.PDF417(x, y, "data", height)

// EAN-13
label.EAN13(x, y, "5901234123457", height)

// UPC-A
label.UPCA(x, y, "012345678905", height)

Adding Graphics

// Box/Rectangle
label.Box(x, y, width, height, thickness)

// Filled box
label.FilledBox(x, y, width, height)

// Horizontal line
label.HorizontalLine(x, y, length, thickness)

// Vertical line
label.VerticalLine(x, y, length, thickness)

// Circle
label.Circle(x, y, diameter, thickness)

Low-Level API

For more control, use the command objects directly:

label.Add(zpl.NewFieldOrigin(100, 200)).
    Add(zpl.NewScalableFont(zpl.FontE, 50, 40).WithOrientation(zpl.OrientationRotated90)).
    Add(zpl.NewFieldData("Rotated Text"))

Output

// Get ZPL as string
zplString := label.String()

// Get ZPL as bytes
zplBytes := label.Bytes()

// Write to io.Writer
label.WriteTo(writer)

// Marshal as text
text, err := label.MarshalText()

Parsing ZPL

import "github.com/StirlingMarketingGroup/go-zpl"

zplString := `^XA
^FO50,50^A0N,30,30^FDHello World^FS
^FO50,100^BQN,2,5^FDMA,https://example.com^FS
^XZ`

label, err := zpl.Parse(zplString)
if err != nil {
    log.Fatal(err)
}

// Work with the parsed label
fmt.Printf("Label has %d commands\n", len(label.Commands()))

// For multi-page ZPL (multiple ^XA...^XZ blocks), use ParseAll:
labels, err := zpl.ParseAll(multiPageZPL)
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Parsed %d labels\n", len(labels))

Rendering to Images

import (
    "os"
    "github.com/StirlingMarketingGroup/go-zpl"
    "github.com/StirlingMarketingGroup/go-zpl/render"
)

// Create or parse a label
label := zpl.NewLabel().
    SetDPI(zpl.DPI203).
    SetSize(4, 6, zpl.UnitInches).
    TextField(50, 50, zpl.Font0, 30, 30, "Hello, World!").
    QRCode(50, 100, "https://example.com", 5)

// Create a renderer
renderer := render.New(zpl.DPI203).WithSize(812, 1218)

// Render to PNG file
f, _ := os.Create("label.png")
defer f.Close()
renderer.RenderPNG(label, f)

Supported Commands

Label Control

• ^XA / ^XZ - Start/end format
• ^PW - Print width
• ^LL - Label length
• ^LH - Label home
• ^PO - Print orientation
• ^PQ - Print quantity

Text & Fonts

• ^A - Scalable/bitmapped fonts
• ^CF - Change default font
• ^CI - Character set
• ^FB - Field block (text wrapping)
• ^FO - Field origin
• ^FT - Field typeset
• ^FD / ^FS - Field data / separator
• ^FR - Field reverse

Barcodes

• ^BC - Code 128
• ^B3 - Code 39
• ^BQ - QR Code
• ^BX - DataMatrix
• ^B7 - PDF417
• ^BD - MaxiCode
• ^BE - EAN-13
• ^BU - UPC-A
• ^B2 - Interleaved 2 of 5
• ^BY - Barcode defaults

Graphics

• ^GB - Graphic box
• ^GC - Graphic circle
• ^GD - Graphic diagonal line
• ^GE - Graphic ellipse
• ^GS - Graphic symbol

License

MIT