Free Online Code 128 Generator

Generating & Printing Code 128 Barcode Images Online

Online Code 128 Generator is developed based on OnBarcode Barcode for .NET.

NOTE

We are providing free online streaming barcode generation service. Now you can generate barcode image through the following url:

http://generator.onbarcode.com/linear.aspx?TYPE=4&DATA=123456789

To get this free online service, please contact us support@onbarcode.com

Watch a quick video tutorial and get started

NOTE

The barcode generator is locked, and you cannot change barcode settings. To unlock it, please go to our YouTube online barcode generator video description section to get the free keycode.

Free barcode generator online video tutorial:
https://youtu.be/hs_ZME55p2Q

Code 128 Barcode Settings
Type:
Barcode Encoding Data
Process Tilde

Code 128 Barcode Text Style
Show Text
Text margin
Text Font Name
Text Font Size
Text Font Style
Text Color

Barcode Colors
Back Color
Fore Color

Unlock Keycode
Code

Code 128 Barcode Image Size Settings
Enable Auto Resize
Bar Alignment
Unit of Measure
X (bar module width)
Y (bar module height)
Left Margin
Right Margin
Top Margin
Bottom Margin
Resolution (in dots per inch)
Rotate
Barcode Image Width (if image width is smaller than the barcode minimum width, the setting will be ignored)
Barcode Image Height (if image height is smaller than the barcode minimum height, the setting will be ignored)
Image Format

Online Barcode Generator Supporting Bar Code Types

OnBarcode barcode products

OnBarcode also provides the following libraries and components for generating, printing, scanning, and reading Code 128 barcodes.

Barcode Software & Libraries

OnBarcode provides professional barcode software and libraries for you.

Barcode Generator for Reporting Services - tutorial with samples for generating, printing barcodes in SQL Server Reporting Services.
Barcode for Java Tutorial - generator tutorial samples for generating, creating barcodes in Java applications.
Barcode Reader for Java Tutorial - generator tutorial samples for reading, scanning barcodes in Java class, iReport, etc.
Barcode Reader for .NET - mature and easy to use barcode generator library sdk to read barcodes in .NET projects.
Barcode Reader for .NET Tutorial - tutorial with samples for reading linear, 2D barcodes in ASP.NET, C# and VB.NET.
Barcode for .NET - reliable barcode generating control dll for generating 1D, 2D barcodes in .NET projects.
Barcode for .NET Tutorial - generator tutorial with samples for generating barcodes in Visual Studio .NET 2005 / 2008/ 2010.
Barcode for ASP.NET - mature barcode generator library sdk to create barcodes in ASP.NET web applications.
Barcode for ASP.NET Tutorial - generator tutorial samples for streaming barcodes in ASP.NET aspx / html pages.
Barcode for NET WinForms Tutorial - generator tutorial samples for creating barcodes in .NET windows applications.
Barcode for C# - generator tutorial with C# samples to create, generate barcodes in Visual C# sample code.
Barcode for VB.NET - generation tutorial with VB.NET samples to print, generate barcodes in VB.NET projects.

QR Code Software & DLLs

OnBarcode provides QR Code software and libraries for you with outstanding quality.

.NET QR Code Reader - mature QR Code recognition control to read, scan QR Code barcodes in .NET.
.NET QR Code Generator Library - generate, create QR Code barcodes in .NET without using barcode fonts.
ASP.NET QR Code Generator DLL - generating QR Code barcode images in ASP.NET web application.
C# QR Code Generator SDK - programmatically create QR Codes using Visual C# in windows and ASP.NET web applications
VB.NET QR Code Generator SDK - using Visual Basic/VB.NET to generate and create QR Code in .NET projects.
Java QR Code Generator Control - easy to use Java QR Code generating library (jar) for Java applications.

Code 128 Software & Components

OnBarcode provides other Code 128 barcode generator library, component and SDK for you.

Code 128 Generator for .NET - how to print, create Code 128 linear barcodes in C#, VB.NET projects & applications.
Code 128 Generator for Java - how to generate, create best Code 128 1D barcode images in Java applications.
Code 128 Generator for VB.NET - how to create, print Code 128 barcodes in C# / VB.NET Windows applications in .NET.
Code 128 Generator for .NET Crystal Report - how to generate, print Code 128 in .NET Crystal Report without barcode fonts.

How to Generate free Code 128 online?

This professional document provides a complete, step-by-step guide to generating and customizing Code 128 (a high-density linear barcode symbology) in online web browser and web application projects. It covers core barcode generation workflows, character encoding rules, code set configuration, check digit logic, HRI display, dimension settings, and GS1 data integration.

Code 128 Barcode Data Encoding for Online Web Applications

Code 128 Supported Character Set

Code 128 supports a full range of characters for web application data encoding:

All 128 Full ASCII characters defined by ISO/IEC 646 standard
Extended ASCII characters (ISO/IEC 8859-1, Latin Alphabet 1, values 128-255) via FNC4 function character
4 non-data function characters for specialized web operations
4 code set selection characters for dynamic encoding switching
3 dedicated start characters for barcode initialization
1 fixed stop character for barcode termination

Code 128 Data Code Sets in Web Projects

Code 128 uses three independent code sets for flexible data encoding in online web applications:

Code Set A
Code Set B
Code Set C

Each set contains a subset of the full ASCII character set and auxiliary symbols.

Web application implementation rules:

Set Type to Code 128 Auto: the library auto-selects the optimal code set for your web data
Manual selection for custom web requirements:
- Code 128 Set A for Code Set A
- Code 128 Set B for Code Set B
- Code 128 Set C for Code Set C

Note: Automatic code set selection is recommended for most online web applications to improve compatibility and scanning speed.

Code 128 Function Characters (FNC) for Web Projects

Function Characters (FNC) are special control characters for barcode readers, supporting advanced web application operations:

FNC1: Designed for the GS1 (global supply chain standard) system; used in GS1-128/ EAN-128 web applications
FNC2: Used for message append operations in multi-part web data transmission
FNC3: Triggers barcode reader initialization or reprogramming for industrial web systems
FNC4: Encodes extended ASCII characters for multilingual web applications

Note: You do not need to manually input function characters in your online web project. The online barcode generator automatically encodes and processes them for web compatibility.

Code 128 Check Digit Character in Online Web Applications

Code 128 includes a mandatory check digit (checksum) calculated by the Mod 103 (module 103) algorithm
The check digit is hidden in HRI and not returned by standard barcode decoders
The online generator automatically generates and appends the check digit before the stop character for all web-based barcodes

Note: Do not attempt to enable/disable check digits for Code 128 in web projects. The online application enforces mandatory check digit generation for compliance.

Code 128 HRI (Human Readable Interpretation) in Web Browsers

HRI (Human Readable Interpretation) is the readable text displayed with the Code 128 barcode in web browsers.

It must stay within quiet zone boundaries for web UI compliance.

Code 128 Barcode Dimension Settings for Online Web Applications

Customize barcode size to fit web browser UI and responsive design requirements using these core properties:

UOM (Unit of Measure): Measurement unit for web rendering; supports PIXEL, CM, INCH (PIXEL recommended for browsers)
X: Width of the narrow barcode module; minimum value defined by your web application specification
Y: Height of the barcode module; adjusted for web page display clarity
LeftMargin / RightMargin: Quiet zone (blank border area); minimum width = 10X to ensure web scanning compatibility