The lets developers build web applications hosted on Google's infrastructure, and developers have long complained that the current search API is inadequate.

"Beside the cruel irony [of] not having full-text search I am starting to wonder why it would take Google so long to implement this," a developer in the App Engine forum last month.

Google released the full-text search API in "experimental" mode and warned it could make changes in future versions that might be incompatible with the current API.

The API will allow users to search by keyword and delineate specific fields and ranges, Google said. The new capabilities also include scoring and snippeting.

Developers can use the API for free up to 20,000 calls a day or a total index size of 250 megabytes.