Limitations
Fireemu does not yet reproduce every feature and behavior of production Firebase. This page lists the main limitations; it is not exhaustive. Check individual APIs in the capability manifest, or run:
npx fireemu capabilitiesUnsupported products
Section titled “Unsupported products”Firebase Hosting, App Hosting and Data Connect are not currently supported. Firebase Extensions support is not planned.
Unsupported features
Section titled “Unsupported features”| Product | Unsupported features and limitations |
|---|---|
| Cloud Firestore | The Enterprise Pipeline API supports a limited subset of read operations (see Enterprise pipelines). Full-text search validates index definitions, but searches are not executed locally. |
| Authentication | Sign-in flows that talk to external identity providers, authorization-code exchange and SAML XML signature verification. Provider configuration and local sign-in are supported. |
| Cloud Storage | Verifying the signature of a signed URL or a POST policy (their expiry and conditions are checked), object ACLs other than allUsers read, IAM and bucket-level public access, object composition (compose) and notification configuration. |
| Realtime Database | No compatibility claim yet: production has not been observed. Comparison is limited to recorded official-emulator cases. The listed unsupported syntax and evaluation cases are refused when rules load or produce rule errors. The eight recorded patterns refused by the official emulator’s determinization resource limit are also rejected when fireemu loads rules, including in unevaluated expression branches. This does not establish complete regular-expression or production equivalence. Rules coverage reports, Functions triggers and a UI view are not supported. Behavior taken from the official emulator where production has not been observed may change. See Realtime Database. |
| Cloud Functions | Triggers for products Fireemu does not deliver events for, such as Realtime Database (an open gap), Remote Config (deferred) and Data Connect (deferred). The exact shape of Storage archive events, which is unrecorded. |
| Cloud Pub/Sub | Schemas, BigQuery and Cloud Storage subscription delivery, and some APIs such as UpdateTopic. |
| App Check | Attestation through Play Integrity, App Attest, DeviceCheck or reCAPTCHA, and replay protection with limited-use tokens. Local testing with debug tokens is supported. |
Differences no local emulator removes
Section titled “Differences no local emulator removes”A successful local operation does not guarantee the same result in production. Fireemu does not reproduce real quota accounting, billing, IAM, organization policies, regional or network differences, or service rollouts. Local performance does not predict production latency or throughput.
Security Rules and API behavior are implemented from documentation and from observations of Firebase’s actual behavior. Changes in Firebase, or conditions that have not been tested, may introduce differences that have not been recorded yet.
Local limits
Section titled “Local limits”Some limits exist only in Fireemu, to bound memory use: the Firestore history limits and the optional Storage stored-byte limit.
Changes between versions
Section titled “Changes between versions”Configuration and behavior may change between releases. See the CHANGELOG.