Cloud Functions can be seamlessly integrated with other Firebase Products and third-party APIs.

Your custom functions can be executed on specific events, which can be emitted by the listed Firebase products:

• Cloud Firestore Triggers
• Realtime Database Triggers
• Firebase Authentication Triggers
• Google Analytics for Firebase Triggers
• Cloud Storage Triggers
• Cloud Pub/Sub Triggers
• HTTP Triggers

You can use Firebase Admin SDK for seamless integration of across different Firebase products. It is very useful in some of the most common application requirements. Let's say that you want to generate database indexes or audit logs when something changes in your real-time database; you can write a cloud function that is executed based on Realtime database triggers. The other way around, you can do some database operation based on specific user behavior. Similarly, you can integrate Cloud Functions with Firebase Cloud Messaging (FCM) to notify users when specific events occur in your database.

Cloud Functions integration is not limited to only Firebase products; you can also integrate Cloud Functions with some third-party API services—by writing webhooks. Let's say you are part of a development team and want to update your Slack channel when somebody commits the code to Git. You can use the Git Webhook API, which will trigger your Cloud Function that executes logic to send the message to the Slack Channel. Similarly, you may use third-party Auth provider APIs, such as LinkedIn, to allow user login.