Understanding Data and File Storage
To store data and files on App Engine, you can use Google Cloud servicesor any other storage service that is supported by your language and isaccessible from your App Engine instance. Third-party databasescan be hosted on another cloud provider,hosted on premises, or managed by a third-party vendor.
Google Cloud storage services
For App Engine apps running in the Python 2 standard environment, we recommendone of the following Google Cloud storage services:
| Name | Structure | Consistency | Cost |
|---|---|---|---|
| Firestore in Datastore mode | Schemaless (NoSQL) | Strongly consistent except when performing global queries. | Datastore mode offers a free quota with daily limits. Paid accounts offer unlimited storage, read, and write operations. More information is available on theDatastore Quotas page. |
| Cloud SQL for MySQL or Cloud SQL for PostgreSQL | Relational | Strongly consistent | Google offers two billing plans for Google Cloud SQL: packages and per use. More information is available in theCloud SQL price sheet. |
| Cloud Storage | Files and their associated metadata (Cloud file storage) | Strongly consistent except when performing list operations that get a list of buckets or objects. | There are no charges associated with making calls to Google Cloud Storage. However, any data stored in Google Cloud Storage is charged the usual Google Cloud Storage data storage fees. Cloud Storage prices are available on theCloud Storage price sheet. |
These options are not mutually exclusive. For example, the same applicationcan store information in a Cloud SQL database, and also store files in a CloudStorage bucket.
See a complete list of the Google Cloud storage products on theCloud Storage Products page.
Other cloud providers
App Engine apps can connect to external databases that are hosted onother public clouds as long as those database servers and your firewall areconfigured properly to accept connections. Your App Engine app connectsover the Internet using that external service's public IP address.
Databases managed by a third-party vendor
There are many vendors offering managed database services such asmLab for MongoDB, Redis Labs offers hostedRedis caching. These vendors handlehosting, configuration, and maintenance of databases. App Engine canconnect to these external services over the Internet, in the same way as otherpublic clouds by using that service's public IP address.
On premises
If you have existing on-premises databases that you want to make accessible toyour App Engine app, you can either configure your internalnetwork and firewall to give the database a public IP address or connect using aVPN.
Production considerations
App Engine can be configured to automatically scale your applicationhorizontally based on various metrics. Unlike web applications, databases oftenrequire non-trivial changes to respond to scale. In production applications,App Engine can quickly overwhelm a database during traffic spikes. Youshould take the anticipated average traffic load and load during spikes intoconsideration when configuring and deploying databases.
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Last updated 2025-12-15 UTC.