Cropping, editing, resizing, and adding text to images are various actions that bloggers and photographers constantly perform. The most popular tools used to perform these actions range from high-performance products like Adobe Photoshop to the free-for-all Paint.NET and GIMP applications. However, the start-up times for these products can waste precious seconds if you only need to perform one action. Here are three great programs for Mac and Windows to resize images on the fly.

Resizr

Resizr is an online image resizer that does just about everything any desktop image resizer could do. Upload a JPEG file from your computer or provide a link to an image on the web and Resizr will do the heavy lifting. The service automatically keeps the image proportions. All you'll have to do is pick a maximum image width. Carry the easily accessible functionality of Resizr to every webpage you visit with their Firefox extension. We promise you won't regret it.

Shrink O'Matic for Windows and Linux

Shrink O'Matic is a great AIR app for quickly resizing any image. Simply drag and drop an image into the app and Shrink O'Matic will take care of the rest. Resize your images with custom size settings or by ratio. You can also save an image as the original file type or another. Since resizing is made to be quick and easy there are some limitations with this AIR app. For example, it only handles JPEG, PNG, and GIF files. Also, there are no other editing options. This app is all about resizing and does a great job of doing so. Since it's an AIR app, it should work on both Linux and Windows OS.

ResizeIt for Mac

This tiny Mac app may be small, but it packs quite the punch. ResizeIt is the perfect app for Mac users to quickly resize images and swap file types at any given time. Unlike the drag-and-drop interface of Shrink O'Matic, you're prompted to select your image upon opening ResizeIt. ResizeIt also allows you to rotate images, which Shrink O'Matic doesn't do. However, Windows users won't have to worry about this feature due to Windows built-in image editor. You can also create presets for common actions. Essentially, ResizeIt is a great on the fly image resizer for Mac users.