Microsoft's Office suite may have its work cut out following the release today of search giant Google's new business Apps Store.

The service, called Google Apps Marketplace, will integrate with its Google Apps software suite which is currently used by more than two million businesses.

The Google Apps Marketplace will be open to developers and more than 50 companies have been involved in the creation of business apps on the platform.

It will offer business software such as a project management application, a tax and payroll program, an electronic fax program, an e-signature service, and a design tool for Google Docs.

Third-party applications include the following, according to a blog by Chris Vander Mey, product manager for Google Apps Marketplace:

• Intuit Online Payroll: A small business application that offers business owners a new way to run payroll, pay taxes and let employees check paystubs using one integrated online office environment.
• Manymoon: A free work and project management application for Google Apps that allows businesses and teams to easily share information including tasks, projects, documents, status updates and links with co-workers, customers and partners.
• Professional Services Connect (PS Connect): This cloud-based app from Appirio pulls contextually relevant information on people, projects, customers and transactions from a user's domain and puts it inside a Gmail message, allowing business people to make better-informed decisions.
• JIRA Studio: A hosted software development suite from Atlassian, it enables software developers to flow naturally between Gmail, Google Calendar, Google Docs and other design and development tools to better track and manage project issues and workflow.

Charges for participating developers in Google Apps Marketplace will be a fixed $100 (£67) for unlimited applications.

Google Apps currently includes Gmail, Google Calendar and Google Docs, and the new applications store will be competing with Microsoft's Office Web Apps and the new version of Office 10, which launches in June.

Some of the third-party applications will include features that integrate with business's back-end data stores.