Google Drive users can soon look forward to a host of new tools for the Docs and Sheets apps, but they don't necessarily come from the Internet giant itself.

The Chrome maker is launching new online marketplaces dedicated to add-ons, introducing new editing and formatting functionality when producing documents or spreadsheets.

The program is still in developer preview mode, but it is gearing up to launch with more than 50 add-ons in tow, all built by partners using Google Apps Script.

Some provided examples of the add-ons that should be ready soon include more tools for mail merge and customized emails, importing names and addresses for printing labels, and a bibliography genie.

Read this Office in the cloud: Google Apps vs. Office 365 Can you do all of your office productivity, email and collaboration in the cloud? We examined the latest small-business suites from Google and Microsoft to find out. Read More

Dan Lazin, a technical writer for the Google Apps team, explained further in a blog post on Tuesday that the tools and APIs for add-ons are available to everyone. The Google Apps team only steps in ahead of final publication to the store.

From there, developers can submit working prototypes of add-ons to Google Apps for admission. At launch, Google has 25 add-on partners. Add-ons will do everything from print labels to customize emails. For instance, PandaDoc is an add-on that allows you to create legally binding documents with digital signatures, notations and other features.

This isn't the first time that the Google Drive team has put the spotlight on its third-party ecosystem, increasingly becoming an advertising point for cloud services providers from Salesforce.com to Box and Dropbox , among many more.

Just a little over a year ago , Google reformatted the Drive sidebar menu so that "Drive-connected" apps would be displayed at the same level as Google-produced apps such as Docs and Sheets.

Google has also been busy targeting corporate Google Apps users this week. On Monday , the Mountain View, Calif.-headquartered company introduced a new referral program rewarding $15 bonus per new user subscription. The program suggests a new strategy in taking on Microsoft Office 365.

For another look at the Google Docs and Sheets Add-Ons, check out the promo video below:

)

Screenshot via the Google Drive blog