Firestore vs Realm
Firestore
cloud.google.com
Realm
realm.github.ioSide by side
| Figure | Firestore | Realm |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | Yes | — |
| Open source | — | — |
| Web | Yes | — |
| Windows | — | Yes |
| macOS | — | Yes |
| Linux | — | Yes |
| iOS | Yes | Yes |
| Android | Yes | Yes |
| API | Yes | — |
| Self-hosted | — | Yes |
| Plans published | 9 | 1 |
| Spec score · Mobile Databases | 9.2 (#1) | 7.7 (#18) |
| Data model | Firestore is a flexible, scalable JSON database for mobile, web, and server development. | Realm exposes data as objects that can be queried in code without an ORM. |
| Integrations | The product page names Google AI Studio, remote MCP, LangChain, and LlamaIndex integrations for building generative AI applications. | Realm's former Device Sync connected data across users, devices, and a backend in real time. |
| Product | Firestore is a fully managed, serverless document database for building AI, web, and mobile applications. | Realm is an object database designed to run directly on phones, tablets, and wearables. |
| Security | Firestore integrates with Cloud IAM, Cloud Identity Platform, and Firebase Authentication for identity-based access controls and data validation. | Realm Swift says data can be encrypted in flight and at rest. |
Plans
Firestore
- Standard edition — document readsPrice not published
- Standard edition — document writesPrice not published
- Standard edition — document deletesPrice not published
- Standard edition — stored dataPrice not published
- Free quotaFree
- Free quotaFree
- Standard edition pay-as-you-go$0.03 a month
- Enterprise editionPrice not published
- Standard editionPrice not published
In their own words
Firestore
Firestore is a fully managed, serverless document database for building AI, web, and mobile applications. It stores flexible JSON data and supports vector search, full-text search, geospatial queries, and ACID transactions on JSON or BSON-compatible documents. Client SDKs for Android, iOS, and web provide real-time updates and automatic syncing for offline access. Firestore can replicate data across multiple regions with strong consistency; multi-region deployments have a stated 99.999% SLA-backed availability. Integrations named for generative AI application work include Google AI Studio, remote MCP, LangChain, and LlamaIndex. Identity controls connect with Cloud IAM, Cloud Identity Platform, and Firebase Authentication. Data is encrypted before it is written to disk, with customer-managed keys available through Cloud KMS. The free quota applies to one database per project and includes 1 GiB of storage, daily read, write, and delete allowances, and 10 GiB monthly outbound transfer. New customers receive $300 in credits, separate from that quota. Server client libraries bypass Firestore Security Rules, so server access needs IAM controls.
Realm
Realm is an object database for local data persistence in mobile and edge applications. It runs directly on phones, tablets, and wearables, and presents data as objects that developers can query in code without an ORM. The database supports relationships, generics, and vectorization. Its documentation describes apps continuing to work through weak signal, offline periods, or outages. Listed SDKs include Java, Swift, Objective-C, JavaScript, and .NET; the JavaScript implementation supports React Native on iOS and Android, as well as Node.js and Electron on Windows, macOS, and Linux. Realm Swift supports encryption in transit and at rest. Realm Studio can open and edit local and synced Realms and administer Realm Object Server instances. Former Device Sync connected data across users, devices, and a backend in real time, but MongoDB announced deprecation of Device Sync and Realm SDKs in September 2024. Realm is free and open source under Apache License 2.0.