API reference › @evolu/common › local‑first/Evolu › EvoluConfig

Defined in: packages/common/src/local-first/Evolu.ts:85

Properties

appName

readonly appName: string & Brand<"UrlSafeString"> & Brand<"AppName">;

Defined in: packages/common/src/local-first/Evolu.ts:106

The app name. Evolu is multitenant - it can run multiple instances concurrently. The same app can have multiple instances for different accounts.

Evolu derives the final instance name from appName and appOwner in EvoluConfig. The derived instance name is used as the SQLite database filename and as the log prefix. This ensures that each Owner gets a separate local database while preserving a readable app prefix.

Example

import { AppName, assertEqual } from "@evolu/common";

const appName = AppName.orThrow("MyApp");
assertEqual(appName, "MyApp");

appOwner

readonly appOwner: AppOwner;

Defined in: packages/common/src/local-first/Evolu.ts:129

AppOwner used to create this Evolu instance.

Exposed as Evolu.appOwner. Create an AppOwner before the first run, or restore one from secure storage before creating Evolu.

AppOwner controls access to the encrypted local SQLite database. If its secret material (Owner secret / Mnemonic) is not stored safely, data written by that instance is permanently inaccessible.

Best onboarding UX is accountless first use: create an AppOwner, let users try a ready-to-use app, then prompt backup of evolu.appOwner.

Recommended usage:

  • Create and persist an appOwner for first run, then guide the user to back it up after user activity.
  • Pass appOwner restored from secure storage (for example, Expo SecureStore, WebAuthn-backed storage, or app-managed account recovery flow).

indexes?

readonly optional indexes?: IndexesConfig;

Defined in: packages/common/src/local-first/Evolu.ts:268

Use the indexes option to define SQLite indexes.

Table and column names are not typed because Kysely doesn't support it.

https://medium.com/@JasonWyatt/squeezing-performance-from-sqlite-indexes-indexes-c4e175f3c346

Example

import {
  AppName,
  assertTrue,
  createAppOwner,
  createEvolu,
  createOwnerSecret,
  createRandomBytes,
  id,
} from "@evolu/common";

const Schema = {
  todo: { id: id("Todo") },
  todoCategory: { id: id("TodoCategory") },
};
// Create once, persist the mnemonic securely, and restore it on later runs.
const appOwner = createAppOwner(
  createOwnerSecret({ randomBytes: createRandomBytes() }),
);

const createTodoEvolu = createEvolu(Schema, {
  appName: AppName.orThrow("IndexedTodos"),
  appOwner,
  transports: [],
  indexes: (create) => [
    create("todoCreatedAt").on("todo").column("createdAt"),
    create("todoCategoryCreatedAt").on("todoCategory").column("createdAt"),
  ],
});

assertTrue(typeof createTodoEvolu === "function");

memoryOnly?

readonly optional memoryOnly?: boolean;

Defined in: packages/common/src/local-first/Evolu.ts:222

Keep local data only in memory instead of persisting it on this device. Useful for testing, temporary data, or sensitive data that should not be recoverable from local storage after the process ends.

Local data stored in memory is completely destroyed when the process ends. Sync can still persist data remotely when transports are enabled.

The default value is: false.

onDatabaseDeleted?

readonly optional onDatabaseDeleted?: () => void;

Defined in: packages/common/src/local-first/Evolu.ts:276

Called when this instance's local database is deleted.

Apps can use this to update UI immediately because the corresponding Evolu instance becomes unusable after local database deletion.

onOwnerDeleted?

readonly optional onOwnerDeleted?: (owner: Owner) => void;

Defined in: packages/common/src/local-first/Evolu.ts:284

Called when local data for an Owner is deleted.

Apps can use this to update UI immediately because that owner stops being used across tabs and instances.

transports?

readonly optional transports?: readonly OwnerWebSocketTransport[];

Defined in: packages/common/src/local-first/Evolu.ts:210

Transport configuration for sync and backup.

If not specified, Evolu uses the default Evolu relay. Pass one or more transports to override it with your own relays. Pass an empty array to disable sync, which is useful when sync should be configured later.

Empty transports start the instance without sync. In that case, Evolu.useOwner must be called with explicit non-empty transports to enable sync for any Owner, including the AppOwner.

Redundancy: The ideal setup uses at least two completely independent relays - for example, a home relay and a geographically separate relay. Data is sent to both relays simultaneously, providing true redundancy similar to using two independent clouds. This eliminates vendor lock-in and ensures your app continues working regardless of circumstances - whether home relay hardware fails or disappears, or a remote relay provider shuts down.

Currently supports:

  • WebSocket: Real-time bidirectional communication with relay servers

Use createOwnerWebSocketTransport to create WebSocket transport configurations with proper URL formatting and OwnerId inclusion. The OwnerId in the URL enables relay authentication, allowing relay servers to control access (e.g., for paid tiers or private instances).

The default value is:

[{ type: "WebSocket", url: "wss://free.evoluhq.com" }].

Example

import {
  assertEqual,
  createAppOwner,
  createOwnerWebSocketTransport,
  createOwnerSecret,
  createRandomBytes,
  type OwnerTransport,
} from "@evolu/common";

// Create once, persist the mnemonic securely, and restore it on later runs.
const appOwner = createAppOwner(
  createOwnerSecret({ randomBytes: createRandomBytes() }),
);

// Use one relay.
const _singleRelay = [
  { type: "WebSocket", url: "wss://relay1.example.com" },
] satisfies ReadonlyArray<OwnerTransport>;

// Use independent relays for redundancy.
const _redundantRelays = [
  { type: "WebSocket", url: "wss://relay1.example.com" },
  { type: "WebSocket", url: "wss://relay2.example.com" },
] satisfies ReadonlyArray<OwnerTransport>;

// Start local-only before authentication. After authentication, pass an
// owner-scoped transport to evolu.useOwner.
const _localOnlyBeforeAuthentication =
  [] satisfies ReadonlyArray<OwnerTransport>;

// Include the OwnerId when the relay authenticates owners.
const authenticatedRelay = [
  createOwnerWebSocketTransport({
    url: "wss://relay.example.com",
    ownerId: appOwner.id,
  }),
];

assertEqual(
  authenticatedRelay[0]?.url,
  `wss://relay.example.com?ownerId=${appOwner.id}`,
);
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