UPDATE: API access is not normally supported in GE and PE orgs. However, after your app passes the security review, you’re eligible to use some APIs for building composite applications.

SOURCE: https://developer.salesforce.com/docs/atlas.en-us.packagingGuide.meta/packagingGuide/dev_packages_api_access.htm

UPDATE: API access is not normally supported in GE and PE orgs. However, after your app passes the security review, you’re eligible to use some APIs for building composite applications.

API Access to GE and PE:

Web Services (SOAP) ---> Yes, with token

Apex methods exposed as Web services (SOAP) ----> No

Web services (REST) ---> Yes, with connected app consumer whitelisting

Apex methods exposed as Web services (REST) ---> Yes, with connected app consumer whitelisting

Chatter REST API ---> Yes

Metadata API ---> Yes, with token

Bulk API ---> No

Data Loader tool (uses SOAP Web services) ---> No, can’t set the token

SOURCE: https://developer.salesforce.com/docs/atlas.en-us.packagingGuide.meta/packagingGuide/dev_packages_api_access.htm