Screenshots: Five apps perfectly suited for a one-person IT shop

Invoice2go

Invoice2go is one of the best invoicing solutions you will ever find (in a mobile format). With this tool you can generate client invoices from more than 20 templates—or even customize your own template. Invoice2go offers just about every feature you would ever need from a mobile invoicing system. You can estimate, organize clients/contacts, invoice, set reminders, sync to other devices, save photos of receipts, add time entries to a built-in calendar, insert location information to invoices, and add barcodes and QR codes to invoices.

Invoice2go

Invoice2go offers a free trial. Once the trial is up, you'll have to choose from one of three plans (ranging from $19/year to $149/year). Check out their plan matrix here.

Square Register

Square Register is one of the most widely used and reliable means to take mobile payments. With Square you can easily (and safely) associate your account to a bank and take payments on the go. Square allows you to set up taxes, signatures (for receipts), tipping, cash drawers, and much more.

Square Register

When you sign up for an account, you will be shipped a free card reader that works with both Android and iOS. Simply plug the reader in and start taking payments. Of course, Square does charge processing fees. To learn about all the fees, go to the Payment and Processing Fees page.

Square offers both email and phone options for support. For more information on contacting Square, you can check out its support page.

Goods Order Inventory Pro

Goods Order Inventory Pro is the only inventory system you need (if you don't need POS integration). It enables you to take care of nearly every inventory task imaginable, including centralized data management, inventory management, user tracking, multiple organizations and locations, inventory movement (across locations), user permissions, and quick reporting. This is a powerhouse mobile inventory solution.

Goods Order Inventory Pro

If you're concerned about having to enter all your inventory from a mobile device, fear not. You can enter everything from your Goods Order Inventory Pro account via the easy to use web interface. You can use the app and service for free, but you're limited to one user and up to 25 products. For more users and products, check out the pricing matrix.

Jiffy

Jiffy is one of my favorite time tracking apps. It not only helps you keep track of all your time, it does so with an incredibly clean and well-designed interface. Because the designers had a keen eye for efficiency, the app is easy to use.

Jiffy

With Jiffy you can keep track of time spent for all your customers and projects and even modify entries when something needs to be changed.

MobiDB Database Designer Lite

MobiDB Database Designer Lite will allow you to keep track of all your client licensing. Why use this instead of a spreadsheet? MobiDB lets you create custom databases perfectly tuned for your needs. If you don't need a customized database, the preconfigured listing includes a database for, you guessed it, software! The software database includes fields for name, key, license, vendor, price, date of purchase, where purchased, and comments. Other features include a barcode scanner, filtering, multiple tables/relations, data entry via form, and 14 supported field types.

MobiDB Database Designer Lite

The free version of MobiDB limits you to 1,000 entries per database. If you need more, you'll have to purchase the Standard version for $10.00 USD.