Online Barcode Generator: Your Complete Tutorial for Barcodes, QR Codes, Labels and Rent Invoice Automation

What Is an Online Barcode Generator?

An online barcode generator is a web-based tool that lets you create barcode images instantly from any text or number you enter. Instead of installing complex software, you simply open a website, choose a barcode type, type the data you want to encode (for example, a product code or invoice number), and the tool returns a ready-to-use barcode as an image file. Most modern generators support popular one-dimensional (1D) barcodes such as Code 128, Code 39, EAN, and UPC, as well as two-dimensional (2D) codes like QR codes. You can then place these barcodes on product labels, packaging, documents, or a rent invoice to simplify scanning and tracking.

Why Use Barcodes and QR Codes in Your Business?

Barcodes convert human-readable data into a machine-readable pattern of lines or squares. When you scan them with a barcode scanner, a mobile app, or even a laptop webcam, the device instantly decodes the data and sends it to your inventory system, billing software, or spreadsheet. This eliminates manual typing, reduces errors, and speeds up everyday workflows such as creating invoices, checking out customers, or counting stock.

Typical use cases include assigning barcodes to products for inventory control, tracking equipment in a warehouse, labeling files and folders for quick retrieval, and adding a unique barcode to every rent invoice so you can reconcile payments in seconds. In rental businesses, barcodes help link items (such as tools, furniture, or vehicles) to contracts and invoices, making it easy to see which tenant is responsible for each asset and whether it has been returned.

Main Types of Barcodes You Can Generate Online

Before you start using any online barcode generator, it helps to know the most common barcode formats:

1D (linear) barcodes use vertical lines of varying thickness.

Examples include:

Code 128 – Very flexible, encodes letters, numbers, and symbols, often used for internal inventory labels, warehouse shelving, and logistics.

Code 39 – Simpler format that also supports letters and numbers, commonly used in manufacturing and asset labels.

EAN‑13 / EAN‑8 – Standard retail barcodes used worldwide on consumer products in supermarkets and stores.

UPC‑A / UPC‑E – Similar to EAN, widely used in North America on retail items.

2D barcodes store data in both directions (horizontal and vertical), making them capable of holding much more information.

The most popular is the QR code, which can include website URLs, payment links, Wi‑Fi credentials, contact details, and more. A QR code printed on a rent invoice can point to an online payment page or to the tenant’s account in your rental portal.

Step-by-Step: How to Use an Online Barcode Generator

Although every website looks a bit different, the general workflow is similar. Follow these basic steps to create your first barcode or QR code online:

Step 1: Choose a reliable generator
Search for a reputable free online barcode generator. Many tools allow you to generate unlimited barcodes without registration. Look for one that supports the symbology you need (for example, Code 128 or QR code) and that lets you download images in common formats like PNG or JPG.

Step 2: Select the barcode type
Once you open the generator, you will usually see a dropdown list of barcode types. Select the format based on your use case:

Use Code 128 or Code 39 for internal labels and warehouse inventory.
Use EAN or UPC for consumer products intended for retail scanning.
Use QR code if you need to encode a URL, payment link, or longer text.

Step 3: Enter the data to encode
Type the content for the barcode in the data field. For example:

For inventory items, enter the stock keeping unit (SKU) or product code.
For a rent invoice, enter the invoice number, contract number, or a unique reference like "INV-RENT-2025-0001".
For a QR code linked to payment, paste the payment URL or shareable payment link from your banking or payment provider.

Step 4: Adjust size and layout options
Most online barcode generators allow you to change:

The overall width and height of the barcode image.
The resolution (for example, 300 DPI) to ensure good print quality.
The text label shown under the barcode (you can choose to display or hide it).
The margin or quiet zone around the barcode for better scannability.

Step 5: Generate and preview the barcode
Click the "Generate" button. The tool will instantly display a preview of the barcode or QR code. Use a barcode scanner app on your phone to test it. If the scan does not work reliably, adjust the size or contrast and generate again until it scans perfectly.

Step 6: Download the barcode image
When you are satisfied with the preview, download the file in the format you need, commonly PNG for digital use or JPG for simple printing. Some generators also offer SVG for high-quality vector graphics and PDF for label sheets.

Step 7: Insert into documents or label templates
Open your document editor, spreadsheet, or design software and insert the barcode image like any other picture. Resize carefully without stretching too much, because extreme distortion can make barcodes harder to scan. If you are using barcodes on a rent invoice, make sure there is enough white space around the code and that it is not placed too close to borders or text.

Using Barcodes on a Rent Invoice

Adding barcodes to a rent invoice is one of the most effective ways to automate rental accounting. Instead of searching for invoices or contract numbers manually, your team can scan the barcode printed on the invoice or on a tenant’s physical file. This scan can instantly call up the record in your rental management or invoicing software, saving time during payment reconciliation or audits.

Here is a practical way to implement barcodes in your rental workflow:

1. Decide on a unique invoice ID pattern, such as "APT12-2025-01" for Apartment 12, January 2025. Use that ID both as the human-readable invoice number and as the data encoded in the barcode.

2. In your online barcode generator, choose Code 128 if you want a compact linear barcode, or a QR code if you also want to link to an online payment page.

3. Generate the barcode for each invoice ID and save the images in a clearly named folder organized by year and month. Many users choose filenames that match the invoice number to avoid confusion.

4. Insert the barcode near the top-right or bottom-left corner of the rent invoice template. Make sure the text "Invoice Number" or "Tenant ID" is still visible for people who do not use scanners.

5. When tenants pay, your staff can scan the barcode on the paper invoice or on a PDF on screen. The scan can search the invoice number in your software and mark it as paid, dramatically reducing typing errors and reconciliation time.

If you use rental equipment, furniture, or vehicles, you can also label each item with a barcode. The rental contract and rent invoice can then reference the same barcode or item code, ensuring that every charge is associated with exactly the right asset.

Best Practices for Printing and Scanning Barcodes

To make sure your barcodes work smoothly in real life, follow these guidelines when you print and scan them:

Use a high enough resolution (300 DPI or more) for printed documents, especially when printing small barcodes on a rent invoice or receipt.

Maintain strong contrast: black bars on a white background are easiest to read. Avoid light colors, glossy surfaces, or busy patterned backgrounds behind the barcode.

Keep a quiet zone: leave a clear margin around the barcode with no text or graphics. Scanners need this border to detect where the barcode begins and ends.

Test with the same scanning device your staff will use. If you will scan barcodes using mobile phones, print a test invoice and confirm that all codes are readable from typical distances and lighting conditions.

Avoid rotating barcodes at unusual angles. Horizontal barcodes (with vertical bars) are usually easiest for handheld scanners.

Organizing Barcodes for Inventory and Rental Assets

If your business combines product sales with rentals, you can use the same online barcode generator to create labels for all your items. Assign each product, tool, or rental asset its own unique code and use it consistently in your inventory system, documents, and physical labels.

For rental properties, you might generate separate barcodes for buildings, apartments, parking spaces, and storage units. Each rent invoice can then display the barcode for the tenant’s main unit plus individual barcodes for optional services such as parking or storage. This structure lets you quickly see which parts of the bill correspond to which physical assets.

For rental equipment, attach durable barcode stickers to each piece. When creating a rental agreement, scan the assets into your contract. Later, scan them again when the customer returns them to close the rental and generate a final rent invoice with accurate charges and no manual item lookup.

Tips for Choosing the Right Online Barcode Generator

When comparing different generators, consider these points:

Check the list of supported symbologies. Make sure your required formats (such as Code 128, EAN‑13, or QR code) are available.

Look for options to adjust size, resolution, and text labels so you can fine-tune barcodes for labels, packaging, or a compact space on a rent invoice.

Prefer tools that allow free commercial use if you plan to use the barcodes in your business.

If you generate a large quantity of barcodes, see whether the generator supports batch or bulk creation from a spreadsheet. This can be extremely helpful for creating hundreds of product codes or barcoded rent invoice numbers at once.

Finally, consider future integration. Some platforms offer APIs that let your invoicing or inventory software call the generator automatically, so you never need to create barcodes manually again.

Final Thoughts

Using an online barcode generator is one of the fastest ways to bring barcode technology into your daily operations. Whether you need labels for inventory, QR codes for payment links, or unique identifiers on every rent invoice, you can start in minutes with nothing more than a web browser. By standardizing your codes, printing them clearly, and linking them to your existing systems, you create a foundation for accurate, efficient, and scalable business processes.