Both companies offer the APIs at no charge.
The API is a beta service available to any website that is free to consumers, the Mountain View, Calif., search engine said. The company, however, retains the right to put advertising on the map in the future.
The Yahoo Maps API, which is scheduled for release Thursday, enables developers to create customized maps by overlaying content, which could range from weather reports to garage sales, the Sunnyvale, Calif., entertainment portal said. The API technology is based on RSS 2.0, the W3C geo extension and other open standards.
Both companies provide support through discussion groups.