6 Best Invoice Apps for Small Businesses & Service Providers Using Smartphones

Getting paid on time is one of the most critical aspects of running a small business or service-based company. Whether you manage an agency, consultancy, startup, or local service business, invoices play a vital role in maintaining healthy cash flow and financial stability.

In today’s mobile-first environment, creating invoices no longer requires a desktop computer or accounting software installed on a laptop. Modern invoice apps allow business owners to create, customize, send, and track invoices directly from their smartphones. This flexibility is especially useful for business owners who travel frequently, work remotely, or manage operations on the go.

Why Small Businesses Need Invoice Apps on Smartphones

Mobile invoicing apps are no longer a convenience — they are a necessity. Here’s why businesses are rapidly adopting them:

• Faster payments through instant invoice creation and sharing

• Professional branding using ready-made invoice templates
  

• Anytime, anywhere access to billing and client data
  

• Reduced paperwork and fewer manual errors
  

• Better financial control with payment and expense tracking

Using the right invoice app helps businesses appear more professional, improve efficiency, and maintain better relationships with clients.

1. Refrens – Best Overall Invoice App for Small Businesses 

Refrens is a modern and powerful invoicing and billing platform designed specifically for small businesses, agencies, consultants, and service providers. While Refrens is well known as a web-based invoicing system, it is fully optimized for mobile use and works seamlessly on smartphones, making it ideal for managing invoices on the go.

Key Features of Refrens

• Create professional invoices in minutes
  

• Fully customizable invoice templates with business branding
  

• Client and vendor management
  

• Automatic invoice numbering
  

• Tax-ready invoices (sales tax, VAT, GST support)
  

• Payment tracking and automated reminders
  

• Multi-currency invoicing for international clients
  

• Expense tracking and estimates
  

• Recurring invoices and quotations
  

• Purchase order management

Why Refrens Is Ranked #1

Refrens goes far beyond basic invoice generation. It acts as a complete billing and business management platform, allowing companies to handle invoices, estimates, recurring billing, expenses, and client records in one place.

For US and global businesses, Refrens is especially valuable due to its multi-currency support, flexible tax settings, and scalable features. The interface is clean, intuitive, and works smoothly on smartphones without compromising functionality.

Unlike many mobile-only apps, Refrens is suitable for businesses that plan to grow and need more than just simple invoicing.

Best For

• Small businesses
  

• Agencies

• Consulting firms
  

• Service-based companies
  

• Businesses working with domestic and international clients

2. Swift Invoice

Swift Invoice is a mobile-focused invoicing app designed for users who need to generate invoices quickly and efficiently. It emphasizes simplicity and speed, making it suitable for small service businesses with basic invoicing needs.

Key Features

• Quick invoice creation using a simple plus (+) button
  

• Add company name, address, logo, and tax details
  

• Multiple invoice themes
  

• PDF invoice generation
  

• Direct email sharing from the app

Strengths

Swift Invoice is easy to use and requires minimal setup. Business details can be saved in settings, which reduces repetitive data entry. Once configured, invoices can be created in just a few taps.

Limitations

• Limited advanced business features
  

• Not ideal for companies needing automation or detailed reporting

Best For

• Small service providers
  

• Sole proprietors
  

• Businesses with straightforward invoicing needs

3. Invoice Simple

Invoice Simple is designed for business owners who want a clean and straightforward invoicing experience without complex features.

Key Features

• Simple sign-up and setup
  

• Clean interface with clearly organized tabs
  

• Multiple invoice themes (Simple, Professional, Matte)
  

• Android and iOS support
  

• Invoice sharing via email or messaging apps

Strengths

The app is intuitive and easy to navigate, even for users with limited technical knowledge. Its structured layout works well on small smartphone screens.

Limitations

• Advanced features require a paid plan
  

• Customization options are limited compared to full platforms

Best For

• Small businesses
  

• Contractors

• Businesses needing fast invoice creation

4. Zoho Invoice

Zoho Invoice is part of the Zoho ecosystem and offers a robust invoicing solution for businesses that require automation and integrations.

Key Features

• Professional invoice creation
  

• Client and product management
  

• Expense tracking
  

• Automated payment reminders
  

• Integration with Zoho CRM and other Zoho products
  

• Available on Android and iOS

Strengths

Zoho Invoice is feature-rich and well-suited for growing businesses. Automation tools reduce manual work, and expense tracking helps maintain financial clarity.

For companies already using Zoho products, this app integrates seamlessly into existing workflows.

Limitations

• Slight learning curve for new users
  

• Interface may feel complex for very small businesses

Best For

• Small to medium-sized businesses
  

• Agencies
  

• Businesses using the Zoho ecosystem