Google Drive API

Users sign in with Google through OAuth and grant a scope that decides how much of their Drive the app can reach. The narrow drive.file scope covers only files the app created or the user chose (for example in the Google Picker) and keeps Google's app review light; apps asking to read a user's whole Drive must pass a stricter verification, which can include a security assessment. A hidden appDataFolder gives an app private space for settings or backups.

The REST API covers resumable uploads of large files, folders, sharing permissions, search, change notifications, and exporting Google Docs, Sheets and Slides to formats such as PDF and DOCX. Calls are free within per-minute quotas measured in quota units, and Google has announced that usage above a daily threshold will be billed once it has given 90 days' notice.