diff --git a/package.json b/package.json
index 54a9d996..dddd46fc 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,8 @@
     "printWidth": 120,
     "bracketSameLine": true,
     "arrowParens": "avoid",
-    "trailingComma": "all"
+    "trailingComma": "all",
+    "endOfLine": "lf"
   },
   "packageManager": "yarn@3.6.3",
   "dependencies": {
diff --git a/packages/app/src/Pages/settings/tools/follows-relay-health.tsx b/packages/app/src/Pages/settings/tools/follows-relay-health.tsx
index 0ecf8df0..ec676cb6 100644
--- a/packages/app/src/Pages/settings/tools/follows-relay-health.tsx
+++ b/packages/app/src/Pages/settings/tools/follows-relay-health.tsx
@@ -1,5 +1,5 @@
 import { dedupe } from "@snort/shared";
-import { pickTopRelays } from "@snort/system";
+import { OutboxModel } from "@snort/system";
 import { SnortContext } from "@snort/system-react";
 import { ReactNode, useContext, useMemo } from "react";
 import { FormattedMessage, FormattedNumber } from "react-intl";
@@ -31,7 +31,8 @@ export function FollowsRelayHealth({
   }, [hasRelays]);
 
   const topWriteRelays = useMemo(() => {
-    return pickTopRelays(system.relayCache, uniqueFollows, 1e31, "write");
+    const outbox = OutboxModel.fromSystem(system);
+    return outbox.pickTopRelays(uniqueFollows, 1e31, "write");
   }, [uniqueFollows]);
 
   return (
diff --git a/packages/system/package.json b/packages/system/package.json
index 9654c87c..9e475c65 100644
--- a/packages/system/package.json
+++ b/packages/system/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@snort/system",
-  "version": "1.2.8",
+  "version": "1.2.9",
   "description": "Snort nostr system package",
   "type": "module",
   "main": "dist/index.js",
diff --git a/packages/system/src/connection-pool.ts b/packages/system/src/connection-pool.ts
index bc7dbcd5..b4ccbf39 100644
--- a/packages/system/src/connection-pool.ts
+++ b/packages/system/src/connection-pool.ts
@@ -4,7 +4,6 @@ import EventEmitter from "eventemitter3";
 
 import { Connection, RelaySettings } from "./connection";
 import { NostrEvent, OkResponse, TaggedNostrEvent } from "./nostr";
-import { pickRelaysForReply } from "./outbox-model";
 import { SystemInterface } from ".";
 import LRUSet from "@snort/shared/src/LRUSet";
 
@@ -22,7 +21,7 @@ export type ConnectionPool = {
   getConnection(id: string): Connection | undefined;
   connect(address: string, options: RelaySettings, ephemeral: boolean): Promise<Connection | undefined>;
   disconnect(address: string): void;
-  broadcast(system: SystemInterface, ev: NostrEvent, cb?: (rsp: OkResponse) => void): Promise<OkResponse[]>;
+  broadcast(ev: NostrEvent, cb?: (rsp: OkResponse) => void): Promise<OkResponse[]>;
   broadcastTo(address: string, ev: NostrEvent): Promise<OkResponse>;
 } & EventEmitter<NostrConnectionPoolEvents> &
   Iterable<[string, Connection]>;
@@ -126,9 +125,9 @@ export class DefaultConnectionPool extends EventEmitter<NostrConnectionPoolEvent
    * Broadcast event to all write relays.
    * @remarks Also write event to read relays of those who are `p` tagged in the event (Inbox model)
    */
-  async broadcast(system: SystemInterface, ev: NostrEvent, cb?: (rsp: OkResponse) => void) {
+  async broadcast(ev: NostrEvent, cb?: (rsp: OkResponse) => void) {
     const writeRelays = [...this.#sockets.values()].filter(a => !a.Ephemeral && a.Settings.write);
-    const replyRelays = await pickRelaysForReply(ev, system);
+    const replyRelays = (await this.#system.requestRouter?.forReply(ev)) ?? [];
     const oks = await Promise.all([
       ...writeRelays.map(async s => {
         try {
@@ -140,7 +139,7 @@ export class DefaultConnectionPool extends EventEmitter<NostrConnectionPoolEvent
         }
         return;
       }),
-      ...replyRelays.filter(a => !this.#sockets.has(unwrap(sanitizeRelayUrl(a)))).map(a => this.broadcastTo(a, ev)),
+      ...replyRelays?.filter(a => !this.#sockets.has(unwrap(sanitizeRelayUrl(a)))).map(a => this.broadcastTo(a, ev)),
     ]);
     return removeUndefined(oks);
   }
diff --git a/packages/system/src/index.ts b/packages/system/src/index.ts
index 67a2388a..91dae407 100644
--- a/packages/system/src/index.ts
+++ b/packages/system/src/index.ts
@@ -2,7 +2,8 @@ import { RelaySettings } from "./connection";
 import { RequestBuilder } from "./request-builder";
 import { NostrEvent, OkResponse, ReqFilter, TaggedNostrEvent } from "./nostr";
 import { ProfileLoaderService } from "./profile-cache";
-import { AuthorsRelaysCache, RelayMetadataLoader } from "./outbox-model";
+import { AuthorsRelaysCache } from "./outbox";
+import { RelayMetadataLoader } from "outbox/relay-loader";
 import { Optimizer } from "./query-optimizer";
 import { base64 } from "@scure/base";
 import { CachedTable } from "@snort/shared";
@@ -10,6 +11,7 @@ import { ConnectionPool } from "./connection-pool";
 import EventEmitter from "eventemitter3";
 import { QueryEvents } from "./query";
 import { CacheRelay } from "./cache-relay";
+import { RequestRouter } from "./request-router";
 
 export { NostrSystem } from "./nostr-system";
 export { default as EventKind } from "./event-kind";
@@ -34,7 +36,7 @@ export * from "./pow";
 export * from "./pow-util";
 export * from "./query-optimizer";
 export * from "./encrypted";
-export * from "./outbox-model";
+export * from "./outbox";
 
 export * from "./impl/nip4";
 export * from "./impl/nip44";
@@ -155,6 +157,11 @@ export interface SystemInterface {
    * Local relay cache service
    */
   get cacheRelay(): CacheRelay | undefined;
+
+  /**
+   * Request router instance
+   */
+  get requestRouter(): RequestRouter | undefined;
 }
 
 export interface SystemSnapshot {
diff --git a/packages/system/src/nostr-system.ts b/packages/system/src/nostr-system.ts
index 21c77ff4..3d0fc803 100644
--- a/packages/system/src/nostr-system.ts
+++ b/packages/system/src/nostr-system.ts
@@ -18,13 +18,15 @@ import {
   UsersRelays,
   SnortSystemDb,
   QueryLike,
+  OutboxModel,
 } from ".";
 import { EventsCache } from "./cache/events";
-import { RelayMetadataLoader } from "./outbox-model";
+import { RelayMetadataLoader } from "./outbox";
 import { Optimizer, DefaultOptimizer } from "./query-optimizer";
 import { ConnectionPool, DefaultConnectionPool } from "./connection-pool";
 import { QueryManager } from "./query-manager";
 import { CacheRelay } from "./cache-relay";
+import { RequestRouter } from "request-router";
 
 export interface NostrSystemEvents {
   change: (state: SystemSnapshot) => void;
@@ -33,15 +35,54 @@ export interface NostrSystemEvents {
   request: (subId: string, filter: BuiltRawReqFilter) => void;
 }
 
-export interface NostrsystemProps {
-  relayCache?: CachedTable<UsersRelays>;
-  profileCache?: CachedTable<CachedMetadata>;
-  relayMetrics?: CachedTable<RelayMetrics>;
-  eventsCache?: CachedTable<NostrEvent>;
-  cacheRelay?: CacheRelay;
-  optimizer?: Optimizer;
+export interface SystemConfig {
+  /**
+   * Users configured relays (via kind 3 or kind 10_002)
+   */
+  relays: CachedTable<UsersRelays>;
+
+  /**
+   * Cache of user profiles, (kind 0)
+   */
+  profiles: CachedTable<CachedMetadata>;
+
+  /**
+   * Cache of relay connection stats
+   */
+  relayMetrics: CachedTable<RelayMetrics>;
+
+  /**
+   * Direct reference events cache
+   */
+  events: CachedTable<NostrEvent>;
+
+  /**
+   * Optimized cache relay, usually `@snort/worker-relay`
+   */
+  cachingRelay?: CacheRelay;
+
+  /**
+   * Optimized functions, usually `@snort/system-wasm`
+   */
+  optimizer: Optimizer;
+
+  /**
+   * Dexie database storage, usually `@snort/system-web`
+   */
   db?: SnortSystemDb;
-  checkSigs?: boolean;
+
+  /**
+   * Check event sigs on receive from relays
+   */
+  checkSigs: boolean;
+
+  /**
+   * Automatically handle outbox model
+   *
+   * 1. Fetch relay lists automatically for queried authors
+   * 2. Write to inbox for all `p` tagged users in broadcasting events
+   */
+  automaticOutboxModel: boolean;
 }
 
 /**
@@ -50,60 +91,83 @@ export interface NostrsystemProps {
 export class NostrSystem extends EventEmitter<NostrSystemEvents> implements SystemInterface {
   #log = debug("System");
   #queryManager: QueryManager;
+  #config: SystemConfig;
 
   /**
    * Storage class for user relay lists
    */
-  readonly relayCache: CachedTable<UsersRelays>;
+  get relayCache(): CachedTable<UsersRelays> {
+    return this.#config.relays;
+  }
 
   /**
    * Storage class for user profiles
    */
-  readonly profileCache: CachedTable<CachedMetadata>;
+  get profileCache(): CachedTable<CachedMetadata> {
+    return this.#config.profiles;
+  }
 
   /**
    * Storage class for relay metrics (connects/disconnects)
    */
-  readonly relayMetricsCache: CachedTable<RelayMetrics>;
-
-  /**
-   * Profile loading service
-   */
-  readonly profileLoader: ProfileLoaderService;
-
-  /**
-   * Relay metrics handler cache
-   */
-  readonly relayMetricsHandler: RelayMetricHandler;
+  get relayMetricsCache(): CachedTable<RelayMetrics> {
+    return this.#config.relayMetrics;
+  }
 
   /**
    * Optimizer instance, contains optimized functions for processing data
    */
-  readonly optimizer: Optimizer;
+  get optimizer(): Optimizer {
+    return this.#config.optimizer;
+  }
 
-  readonly pool: ConnectionPool;
-  readonly eventsCache: CachedTable<NostrEvent>;
-  readonly relayLoader: RelayMetadataLoader;
-  readonly cacheRelay: CacheRelay | undefined;
+  get eventsCache(): CachedTable<NostrEvent> {
+    return this.#config.events;
+  }
+
+  get cacheRelay(): CacheRelay | undefined {
+    return this.#config.cachingRelay;
+  }
 
   /**
-   * Check event signatures (reccomended)
+   * Check event signatures (recommended)
    */
-  checkSigs: boolean;
+  get checkSigs(): boolean {
+    return this.#config.checkSigs;
+  }
 
-  constructor(props: NostrsystemProps) {
+  set checkSigs(v: boolean) {
+    this.#config.checkSigs = v;
+  }
+
+  readonly profileLoader: ProfileLoaderService;
+  readonly relayMetricsHandler: RelayMetricHandler;
+  readonly pool: ConnectionPool;
+  readonly relayLoader: RelayMetadataLoader;
+  readonly requestRouter: RequestRouter | undefined;
+
+  constructor(props: Partial<SystemConfig>) {
     super();
-    this.relayCache = props.relayCache ?? new UserRelaysCache(props.db?.userRelays);
-    this.profileCache = props.profileCache ?? new UserProfileCache(props.db?.users);
-    this.relayMetricsCache = props.relayMetrics ?? new RelayMetricCache(props.db?.relayMetrics);
-    this.eventsCache = props.eventsCache ?? new EventsCache(props.db?.events);
-    this.optimizer = props.optimizer ?? DefaultOptimizer;
-    this.cacheRelay = props.cacheRelay;
+    this.#config = {
+      relays: props.relays ?? new UserRelaysCache(props.db?.userRelays),
+      profiles: props.profiles ?? new UserProfileCache(props.db?.users),
+      relayMetrics: props.relayMetrics ?? new RelayMetricCache(props.db?.relayMetrics),
+      events: props.events ?? new EventsCache(props.db?.events),
+      optimizer: props.optimizer ?? DefaultOptimizer,
+      checkSigs: props.checkSigs ?? false,
+      cachingRelay: props.cachingRelay,
+      db: props.db,
+      automaticOutboxModel: props.automaticOutboxModel ?? true,
+    };
 
     this.profileLoader = new ProfileLoaderService(this, this.profileCache);
     this.relayMetricsHandler = new RelayMetricHandler(this.relayMetricsCache);
     this.relayLoader = new RelayMetadataLoader(this, this.relayCache);
-    this.checkSigs = props.checkSigs ?? true;
+
+    // if automatic outbox model, setup request router as OutboxModel
+    if (this.#config.automaticOutboxModel) {
+      this.requestRouter = OutboxModel.fromSystem(this);
+    }
 
     this.pool = new DefaultConnectionPool(this);
     this.#queryManager = new QueryManager(this);
@@ -196,7 +260,7 @@ export class NostrSystem extends EventEmitter<NostrSystemEvents> implements Syst
 
   async BroadcastEvent(ev: NostrEvent, cb?: (rsp: OkResponse) => void): Promise<OkResponse[]> {
     this.HandleEvent("*", { ...ev, relays: [] });
-    return await this.pool.broadcast(this, ev, cb);
+    return await this.pool.broadcast(ev, cb);
   }
 
   async WriteOnceToRelay(address: string, ev: NostrEvent): Promise<OkResponse> {
diff --git a/packages/system/src/outbox-model.ts b/packages/system/src/outbox-model.ts
deleted file mode 100644
index 52331615..00000000
--- a/packages/system/src/outbox-model.ts
+++ /dev/null
@@ -1,318 +0,0 @@
-import {
-  EventKind,
-  FullRelaySettings,
-  NostrEvent,
-  ReqFilter,
-  RequestBuilder,
-  SystemInterface,
-  TaggedNostrEvent,
-  UsersRelays,
-} from ".";
-import { dedupe, removeUndefined, sanitizeRelayUrl, unixNowMs, unwrap } from "@snort/shared";
-import debug from "debug";
-import { FlatReqFilter } from "./query-optimizer";
-import { RelayListCacheExpire } from "./const";
-import { BackgroundLoader } from "./background-loader";
-
-const DefaultPickNRelays = 2;
-
-export interface RelayTaggedFilter {
-  relay: string;
-  filter: ReqFilter;
-}
-
-export interface RelayTaggedFlatFilters {
-  relay: string;
-  filters: Array<FlatReqFilter>;
-}
-
-export interface RelayTaggedFilters {
-  relay: string;
-  filters: Array<ReqFilter>;
-}
-
-const logger = debug("OutboxModel");
-
-export interface AuthorsRelaysCache {
-  getFromCache(pubkey?: string): UsersRelays | undefined;
-  update(obj: UsersRelays): Promise<"new" | "updated" | "refresh" | "no_change">;
-  buffer(keys: Array<string>): Promise<Array<string>>;
-  bulkSet(objs: Array<UsersRelays>): Promise<void>;
-}
-
-export function splitAllByWriteRelays(cache: AuthorsRelaysCache, filters: Array<ReqFilter>) {
-  const allSplit = filters
-    .map(a => splitByWriteRelays(cache, a))
-    .reduce((acc, v) => {
-      for (const vn of v) {
-        const existing = acc.get(vn.relay);
-        if (existing) {
-          existing.push(vn.filter);
-        } else {
-          acc.set(vn.relay, [vn.filter]);
-        }
-      }
-      return acc;
-    }, new Map<string, Array<ReqFilter>>());
-
-  return [...allSplit.entries()].map(([k, v]) => {
-    return {
-      relay: k,
-      filters: v,
-    } as RelayTaggedFilters;
-  });
-}
-
-/**
- * Split filters by authors
- */
-export function splitByWriteRelays(
-  cache: AuthorsRelaysCache,
-  filter: ReqFilter,
-  pickN?: number,
-): Array<RelayTaggedFilter> {
-  const authors = filter.authors;
-  if ((authors?.length ?? 0) === 0) {
-    return [
-      {
-        relay: "",
-        filter,
-      },
-    ];
-  }
-
-  const topRelays = pickTopRelays(cache, unwrap(authors), pickN ?? DefaultPickNRelays, "write");
-  const pickedRelays = dedupe(topRelays.flatMap(a => a.relays));
-
-  const picked = pickedRelays.map(a => {
-    const keysOnPickedRelay = dedupe(topRelays.filter(b => b.relays.includes(a)).map(b => b.key));
-    return {
-      relay: a,
-      filter: {
-        ...filter,
-        authors: keysOnPickedRelay,
-      },
-    } as RelayTaggedFilter;
-  });
-  const noRelays = dedupe(topRelays.filter(a => a.relays.length === 0).map(a => a.key));
-  if (noRelays.length > 0) {
-    picked.push({
-      relay: "",
-      filter: {
-        ...filter,
-        authors: noRelays,
-      },
-    });
-  }
-  logger("Picked %O => %O", filter, picked);
-  return picked;
-}
-
-/**
- * Split filters by author
- */
-export function splitFlatByWriteRelays(
-  cache: AuthorsRelaysCache,
-  input: Array<FlatReqFilter>,
-  pickN?: number,
-): Array<RelayTaggedFlatFilters> {
-  const authors = input.filter(a => a.authors).map(a => unwrap(a.authors));
-  if (authors.length === 0) {
-    return [
-      {
-        relay: "",
-        filters: input,
-      },
-    ];
-  }
-  const topRelays = pickTopRelays(cache, authors, pickN ?? DefaultPickNRelays, "write");
-  const pickedRelays = dedupe(topRelays.flatMap(a => a.relays));
-
-  const picked = pickedRelays.map(a => {
-    const authorsOnRelay = new Set(topRelays.filter(v => v.relays.includes(a)).map(v => v.key));
-    return {
-      relay: a,
-      filters: input.filter(v => v.authors && authorsOnRelay.has(v.authors)),
-    } as RelayTaggedFlatFilters;
-  });
-  const noRelays = new Set(topRelays.filter(v => v.relays.length === 0).map(v => v.key));
-  if (noRelays.size > 0) {
-    picked.push({
-      relay: "",
-      filters: input.filter(v => !v.authors || noRelays.has(v.authors)),
-    } as RelayTaggedFlatFilters);
-  }
-
-  logger("Picked %d relays from %d filters", picked.length, input.length);
-  return picked;
-}
-
-/**
- * Pick most popular relays for each authors
- */
-export function pickTopRelays(cache: AuthorsRelaysCache, authors: Array<string>, n: number, type: "write" | "read") {
-  // map of pubkey -> [write relays]
-  const allRelays = authors.map(a => {
-    return {
-      key: a,
-      relays: cache
-        .getFromCache(a)
-        ?.relays?.filter(a => (type === "write" ? a.settings.write : a.settings.read))
-        .sort(() => (Math.random() < 0.5 ? 1 : -1)),
-    };
-  });
-
-  const missing = allRelays.filter(a => a.relays === undefined || a.relays.length === 0);
-  const hasRelays = allRelays.filter(a => a.relays !== undefined && a.relays.length > 0);
-
-  // map of relay -> [pubkeys]
-  const relayUserMap = hasRelays.reduce((acc, v) => {
-    for (const r of unwrap(v.relays)) {
-      if (!acc.has(r.url)) {
-        acc.set(r.url, new Set([v.key]));
-      } else {
-        unwrap(acc.get(r.url)).add(v.key);
-      }
-    }
-    return acc;
-  }, new Map<string, Set<string>>());
-
-  // selection algo will just pick relays with the most users
-  const topRelays = [...relayUserMap.entries()].sort(([, v], [, v1]) => v1.size - v.size);
-
-  // <relay, key[]> - count keys per relay
-  // <key, relay[]> - pick n top relays
-  // <relay, key[]> - map keys per relay (for subscription filter)
-
-  return hasRelays
-    .map(k => {
-      // pick top N relays for this key
-      const relaysForKey = topRelays
-        .filter(([, v]) => v.has(k.key))
-        .slice(0, n)
-        .map(([k]) => k);
-      return { key: k.key, relays: relaysForKey };
-    })
-    .concat(
-      missing.map(a => {
-        return {
-          key: a.key,
-          relays: [],
-        };
-      }),
-    );
-}
-
-/**
- * Pick read relays for sending reply events
- */
-export async function pickRelaysForReply(ev: NostrEvent, system: SystemInterface, pickN?: number) {
-  const recipients = dedupe(ev.tags.filter(a => a[0] === "p").map(a => a[1]));
-  await updateRelayLists(recipients, system);
-  const relays = pickTopRelays(system.relayCache, recipients, pickN ?? DefaultPickNRelays, "read");
-  const ret = removeUndefined(dedupe(relays.map(a => a.relays).flat()));
-  logger("Picked %O from authors %O", ret, recipients);
-  return ret;
-}
-
-export function parseRelayTag(tag: Array<string>) {
-  return {
-    url: sanitizeRelayUrl(tag[1]),
-    settings: {
-      read: tag[2] === "read" || tag[2] === undefined,
-      write: tag[2] === "write" || tag[2] === undefined,
-    },
-  } as FullRelaySettings;
-}
-
-export function parseRelayTags(tag: Array<Array<string>>) {
-  return tag.map(parseRelayTag).filter(a => a !== null);
-}
-
-export function parseRelaysFromKind(ev: NostrEvent) {
-  if (ev.kind === EventKind.ContactList) {
-    const relaysInContent =
-      ev.content.length > 0 ? (JSON.parse(ev.content) as Record<string, { read: boolean; write: boolean }>) : undefined;
-    if (relaysInContent) {
-      return Object.entries(relaysInContent).map(
-        ([k, v]) =>
-          ({
-            url: sanitizeRelayUrl(k),
-            settings: {
-              read: v.read,
-              write: v.write,
-            },
-          }) as FullRelaySettings,
-      );
-    }
-  } else if (ev.kind === EventKind.Relays) {
-    return parseRelayTags(ev.tags);
-  }
-}
-
-export async function updateRelayLists(authors: Array<string>, system: SystemInterface) {
-  await system.relayCache.buffer(authors);
-  const expire = unixNowMs() - RelayListCacheExpire;
-  const expired = authors.filter(a => (system.relayCache.getFromCache(a)?.loaded ?? 0) < expire);
-  if (expired.length > 0) {
-    logger("Updating relays for authors: %O", expired);
-    const rb = new RequestBuilder("system-update-relays-for-outbox");
-    rb.withFilter().authors(expired).kinds([EventKind.Relays, EventKind.ContactList]);
-    const relayLists = await system.Fetch(rb);
-    await system.relayCache.bulkSet(
-      removeUndefined(
-        relayLists.map(a => {
-          const relays = parseRelaysFromKind(a);
-          if (!relays) return;
-          return {
-            relays: relays,
-            pubkey: a.pubkey,
-            created: a.created_at,
-            loaded: unixNowMs(),
-          };
-        }),
-      ),
-    );
-  }
-}
-
-export class RelayMetadataLoader extends BackgroundLoader<UsersRelays> {
-  override name(): string {
-    return "RelayMetadataLoader";
-  }
-
-  override onEvent(e: Readonly<TaggedNostrEvent>): UsersRelays | undefined {
-    const relays = parseRelaysFromKind(e);
-    if (!relays) return;
-    return {
-      relays: relays,
-      pubkey: e.pubkey,
-      created: e.created_at,
-      loaded: unixNowMs(),
-    };
-  }
-
-  override getExpireCutoff(): number {
-    return unixNowMs() - RelayListCacheExpire;
-  }
-
-  protected override buildSub(missing: string[]): RequestBuilder {
-    const rb = new RequestBuilder("relay-loader");
-    rb.withOptions({
-      skipDiff: true,
-      timeout: 10_000,
-      outboxPickN: 4,
-    });
-    rb.withFilter().authors(missing).kinds([EventKind.Relays, EventKind.ContactList]);
-    return rb;
-  }
-
-  protected override makePlaceholder(key: string): UsersRelays | undefined {
-    return {
-      relays: [],
-      pubkey: key,
-      created: 0,
-      loaded: this.getExpireCutoff() + 300_000,
-    };
-  }
-}
diff --git a/packages/system/src/outbox/index.ts b/packages/system/src/outbox/index.ts
new file mode 100644
index 00000000..47500feb
--- /dev/null
+++ b/packages/system/src/outbox/index.ts
@@ -0,0 +1,58 @@
+import { EventKind, FullRelaySettings, NostrEvent, SystemInterface, UsersRelays } from "..";
+import { sanitizeRelayUrl } from "@snort/shared";
+
+export const DefaultPickNRelays = 2;
+
+export interface AuthorsRelaysCache {
+  getFromCache(pubkey?: string): UsersRelays | undefined;
+  update(obj: UsersRelays): Promise<"new" | "updated" | "refresh" | "no_change">;
+  buffer(keys: Array<string>): Promise<Array<string>>;
+  bulkSet(objs: Array<UsersRelays>): Promise<void>;
+}
+
+export interface PickedRelays {
+  key: string;
+  relays: Array<string>;
+}
+
+export type EventFetcher = {
+  Fetch: SystemInterface["Fetch"];
+};
+
+export function parseRelayTag(tag: Array<string>) {
+  return {
+    url: sanitizeRelayUrl(tag[1]),
+    settings: {
+      read: tag[2] === "read" || tag[2] === undefined,
+      write: tag[2] === "write" || tag[2] === undefined,
+    },
+  } as FullRelaySettings;
+}
+
+export function parseRelayTags(tag: Array<Array<string>>) {
+  return tag.map(parseRelayTag).filter(a => a !== null);
+}
+
+export function parseRelaysFromKind(ev: NostrEvent) {
+  if (ev.kind === EventKind.ContactList) {
+    const relaysInContent =
+      ev.content.length > 0 ? (JSON.parse(ev.content) as Record<string, { read: boolean; write: boolean }>) : undefined;
+    if (relaysInContent) {
+      return Object.entries(relaysInContent).map(
+        ([k, v]) =>
+          ({
+            url: sanitizeRelayUrl(k),
+            settings: {
+              read: v.read,
+              write: v.write,
+            },
+          }) as FullRelaySettings,
+      );
+    }
+  } else if (ev.kind === EventKind.Relays) {
+    return parseRelayTags(ev.tags);
+  }
+}
+
+export * from "./outbox-model";
+export * from "./relay-loader";
diff --git a/packages/system/src/outbox/outbox-model.ts b/packages/system/src/outbox/outbox-model.ts
new file mode 100644
index 00000000..60d1df57
--- /dev/null
+++ b/packages/system/src/outbox/outbox-model.ts
@@ -0,0 +1,213 @@
+import { EventKind, NostrEvent, ReqFilter, RequestBuilder, SystemInterface } from "..";
+import { dedupe, removeUndefined, unixNowMs, unwrap } from "@snort/shared";
+import { FlatReqFilter } from "../query-optimizer";
+import { RelayListCacheExpire } from "../const";
+import { AuthorsRelaysCache, EventFetcher, PickedRelays, DefaultPickNRelays, parseRelaysFromKind } from ".";
+import debug from "debug";
+import { BaseRequestRouter, RelayTaggedFilter, RelayTaggedFlatFilters } from "../request-router";
+
+/**
+ * Simple outbox model using most popular relays
+ */
+export class OutboxModel extends BaseRequestRouter {
+  #log = debug("OutboxModel");
+  #relays: AuthorsRelaysCache;
+  #fetcher: EventFetcher;
+
+  constructor(relays: AuthorsRelaysCache, fetcher: EventFetcher) {
+    super();
+    this.#relays = relays;
+    this.#fetcher = fetcher;
+  }
+
+  static fromSystem(system: SystemInterface) {
+    return new OutboxModel(system.relayCache, system);
+  }
+
+  /**
+   * Pick top relays for each user
+   * @param authors The authors whos relays will be picked
+   * @param pickN Number of relays to pick per pubkey
+   * @param type Read/Write relays
+   * @returns
+   */
+  pickTopRelays(authors: Array<string>, pickN: number, type: "write" | "read"): Array<PickedRelays> {
+    // map of pubkey -> [write relays]
+    const allRelays = authors.map(a => {
+      return {
+        key: a,
+        relays: this.#relays
+          .getFromCache(a)
+          ?.relays?.filter(a => (type === "write" ? a.settings.write : a.settings.read))
+          .sort(() => (Math.random() < 0.5 ? 1 : -1)),
+      };
+    });
+
+    const missing = allRelays.filter(a => a.relays === undefined || a.relays.length === 0);
+    const hasRelays = allRelays.filter(a => a.relays !== undefined && a.relays.length > 0);
+
+    // map of relay -> [pubkeys]
+    const relayUserMap = hasRelays.reduce((acc, v) => {
+      for (const r of unwrap(v.relays)) {
+        if (!acc.has(r.url)) {
+          acc.set(r.url, new Set([v.key]));
+        } else {
+          unwrap(acc.get(r.url)).add(v.key);
+        }
+      }
+      return acc;
+    }, new Map<string, Set<string>>());
+
+    // selection algo will just pick relays with the most users
+    const topRelays = [...relayUserMap.entries()].sort(([, v], [, v1]) => v1.size - v.size);
+
+    // <relay, key[]> - count keys per relay
+    // <key, relay[]> - pick n top relays
+    // <relay, key[]> - map keys per relay (for subscription filter)
+    return hasRelays
+      .map(k => {
+        // pick top N relays for this key
+        const relaysForKey = topRelays
+          .filter(([, v]) => v.has(k.key))
+          .slice(0, pickN)
+          .map(([k]) => k);
+        return { key: k.key, relays: relaysForKey };
+      })
+      .concat(
+        missing.map(a => {
+          return {
+            key: a.key,
+            relays: [],
+          };
+        }),
+      );
+  }
+
+  /**
+   * Split a request filter by authors
+   * @param filter Filter to split
+   * @param pickN Number of relays to pick per author
+   * @returns
+   */
+  forRequest(filter: ReqFilter, pickN?: number): Array<RelayTaggedFilter> {
+    const authors = filter.authors;
+    if ((authors?.length ?? 0) === 0) {
+      return [
+        {
+          relay: "",
+          filter,
+        },
+      ];
+    }
+
+    const topRelays = this.pickTopRelays(unwrap(authors), pickN ?? DefaultPickNRelays, "write");
+    const pickedRelays = dedupe(topRelays.flatMap(a => a.relays));
+
+    const picked = pickedRelays.map(a => {
+      const keysOnPickedRelay = dedupe(topRelays.filter(b => b.relays.includes(a)).map(b => b.key));
+      return {
+        relay: a,
+        filter: {
+          ...filter,
+          authors: keysOnPickedRelay,
+        },
+      } as RelayTaggedFilter;
+    });
+    const noRelays = dedupe(topRelays.filter(a => a.relays.length === 0).map(a => a.key));
+    if (noRelays.length > 0) {
+      picked.push({
+        relay: "",
+        filter: {
+          ...filter,
+          authors: noRelays,
+        },
+      });
+    }
+    this.#log("Picked %O => %O", filter, picked);
+    return picked;
+  }
+
+  /**
+   * Split a flat request filter by authors
+   * @param filter Filter to split
+   * @param pickN Number of relays to pick per author
+   * @returns
+   */
+  forFlatRequest(input: Array<FlatReqFilter>, pickN?: number): Array<RelayTaggedFlatFilters> {
+    const authors = input.filter(a => a.authors).map(a => unwrap(a.authors));
+    if (authors.length === 0) {
+      return [
+        {
+          relay: "",
+          filters: input,
+        },
+      ];
+    }
+    const topRelays = this.pickTopRelays(authors, pickN ?? DefaultPickNRelays, "write");
+    const pickedRelays = dedupe(topRelays.flatMap(a => a.relays));
+
+    const picked = pickedRelays.map(a => {
+      const authorsOnRelay = new Set(topRelays.filter(v => v.relays.includes(a)).map(v => v.key));
+      return {
+        relay: a,
+        filters: input.filter(v => v.authors && authorsOnRelay.has(v.authors)),
+      } as RelayTaggedFlatFilters;
+    });
+    const noRelays = new Set(topRelays.filter(v => v.relays.length === 0).map(v => v.key));
+    if (noRelays.size > 0) {
+      picked.push({
+        relay: "",
+        filters: input.filter(v => !v.authors || noRelays.has(v.authors)),
+      } as RelayTaggedFlatFilters);
+    }
+
+    this.#log("Picked %d relays from %d filters", picked.length, input.length);
+    return picked;
+  }
+
+  /**
+   * Pick relay inboxs for replies
+   * @param ev The reply event to send
+   * @param system Nostr system interface
+   * @param pickN Number of relays to pick per recipient
+   * @returns
+   */
+  async forReply(ev: NostrEvent, pickN?: number) {
+    const recipients = dedupe([ev.pubkey, ...ev.tags.filter(a => a[0] === "p").map(a => a[1])]);
+    await this.updateRelayLists(recipients);
+    const relays = this.pickTopRelays(recipients, pickN ?? DefaultPickNRelays, "read");
+    const ret = removeUndefined(dedupe(relays.map(a => a.relays).flat()));
+    this.#log("Picked %O from authors %O", ret, recipients);
+    return ret;
+  }
+
+  /**
+   * Update relay cache with latest relay lists
+   * @param authors The authors to update relay lists for
+   */
+  async updateRelayLists(authors: Array<string>) {
+    await this.#relays.buffer(authors);
+    const expire = unixNowMs() - RelayListCacheExpire;
+    const expired = authors.filter(a => (this.#relays.getFromCache(a)?.loaded ?? 0) < expire);
+    if (expired.length > 0) {
+      this.#log("Updating relays for authors: %O", expired);
+      const rb = new RequestBuilder("system-update-relays-for-outbox");
+      rb.withFilter().authors(expired).kinds([EventKind.Relays, EventKind.ContactList]);
+      const relayLists = await this.#fetcher.Fetch(rb);
+      await this.#relays.bulkSet(
+        removeUndefined(
+          relayLists.map(a => {
+            const relays = parseRelaysFromKind(a);
+            if (!relays) return;
+            return {
+              relays: relays,
+              pubkey: a.pubkey,
+              created: a.created_at,
+              loaded: unixNowMs(),
+            };
+          }),
+        ),
+      );
+    }
+  }
+}
diff --git a/packages/system/src/outbox/relay-loader.ts b/packages/system/src/outbox/relay-loader.ts
new file mode 100644
index 00000000..1ac0d073
--- /dev/null
+++ b/packages/system/src/outbox/relay-loader.ts
@@ -0,0 +1,46 @@
+import { EventKind, RequestBuilder, TaggedNostrEvent, UsersRelays } from "..";
+import { unixNowMs } from "@snort/shared";
+import { RelayListCacheExpire } from "../const";
+import { BackgroundLoader } from "../background-loader";
+import { parseRelaysFromKind } from ".";
+
+export class RelayMetadataLoader extends BackgroundLoader<UsersRelays> {
+  override name(): string {
+    return "RelayMetadataLoader";
+  }
+
+  override onEvent(e: Readonly<TaggedNostrEvent>): UsersRelays | undefined {
+    const relays = parseRelaysFromKind(e);
+    if (!relays) return;
+    return {
+      relays: relays,
+      pubkey: e.pubkey,
+      created: e.created_at,
+      loaded: unixNowMs(),
+    };
+  }
+
+  override getExpireCutoff(): number {
+    return unixNowMs() - RelayListCacheExpire;
+  }
+
+  protected override buildSub(missing: string[]): RequestBuilder {
+    const rb = new RequestBuilder("relay-loader");
+    rb.withOptions({
+      skipDiff: true,
+      timeout: 10000,
+      outboxPickN: 4,
+    });
+    rb.withFilter().authors(missing).kinds([EventKind.Relays, EventKind.ContactList]);
+    return rb;
+  }
+
+  protected override makePlaceholder(key: string): UsersRelays | undefined {
+    return {
+      relays: [],
+      pubkey: key,
+      created: 0,
+      loaded: this.getExpireCutoff() + 300000,
+    };
+  }
+}
diff --git a/packages/system/src/request-builder.ts b/packages/system/src/request-builder.ts
index b71b8ed4..37b1a548 100644
--- a/packages/system/src/request-builder.ts
+++ b/packages/system/src/request-builder.ts
@@ -5,7 +5,7 @@ import { appendDedupe, dedupe, sanitizeRelayUrl, unixNowMs, unwrap } from "@snor
 import EventKind from "./event-kind";
 import { NostrLink, NostrPrefix, SystemInterface } from ".";
 import { ReqFilter, u256, HexKey, TaggedNostrEvent } from "./nostr";
-import { AuthorsRelaysCache, splitByWriteRelays, splitFlatByWriteRelays } from "./outbox-model";
+import { RequestRouter } from "./request-router";
 
 /**
  * Which strategy is used when building REQ filters
@@ -133,7 +133,7 @@ export class RequestBuilder {
   }
 
   build(system: SystemInterface): Array<BuiltRawReqFilter> {
-    const expanded = this.#builders.flatMap(a => a.build(system.relayCache, this.#options));
+    const expanded = this.#builders.flatMap(a => a.build(system.requestRouter, this.#options));
     return this.#groupByRelay(system, expanded);
   }
 
@@ -147,14 +147,24 @@ export class RequestBuilder {
     const ts = unixNowMs() - start;
     this.#log("buildDiff %s %d ms +%d", this.id, ts, diff.length);
     if (diff.length > 0) {
-      // todo: fix for explicit relays
-      return splitFlatByWriteRelays(system.relayCache, diff).map(a => {
-        return {
-          strategy: RequestStrategy.AuthorsRelays,
-          filters: system.optimizer.flatMerge(a.filters),
-          relay: a.relay,
-        };
-      });
+      if (system.requestRouter) {
+        // todo: fix for explicit relays
+        return system.requestRouter.forFlatRequest(diff).map(a => {
+          return {
+            strategy: RequestStrategy.AuthorsRelays,
+            filters: system.optimizer.flatMerge(a.filters),
+            relay: a.relay,
+          };
+        });
+      } else {
+        return [
+          {
+            strategy: RequestStrategy.DefaultRelays,
+            filters: system.optimizer.flatMerge(diff),
+            relay: "",
+          },
+        ];
+      }
     }
     return [];
   }
@@ -294,11 +304,11 @@ export class RequestFilterBuilder {
   /**
    * Build/expand this filter into a set of relay specific queries
    */
-  build(relays: AuthorsRelaysCache, options?: RequestBuilderOptions): Array<BuiltRawReqFilter> {
-    return this.#buildFromFilter(relays, this.#filter, options);
+  build(model?: RequestRouter, options?: RequestBuilderOptions): Array<BuiltRawReqFilter> {
+    return this.#buildFromFilter(this.#filter, model, options);
   }
 
-  #buildFromFilter(relays: AuthorsRelaysCache, f: ReqFilter, options?: RequestBuilderOptions) {
+  #buildFromFilter(f: ReqFilter, model?: RequestRouter, options?: RequestBuilderOptions) {
     // use the explicit relay list first
     if (this.#relays.size > 0) {
       return [...this.#relays].map(r => {
@@ -311,8 +321,8 @@ export class RequestFilterBuilder {
     }
 
     // If any authors are set use the gossip model to fetch data for each author
-    if (f.authors) {
-      const split = splitByWriteRelays(relays, f, options?.outboxPickN);
+    if (f.authors && model) {
+      const split = model.forRequest(f, options?.outboxPickN);
       return split.map(a => {
         return {
           filters: [a.filter],
diff --git a/packages/system/src/request-router.ts b/packages/system/src/request-router.ts
new file mode 100644
index 00000000..008b7f58
--- /dev/null
+++ b/packages/system/src/request-router.ts
@@ -0,0 +1,76 @@
+import { NostrEvent, ReqFilter } from "./nostr";
+import { FlatReqFilter } from "./query-optimizer";
+
+export interface RelayTaggedFilter {
+  relay: string;
+  filter: ReqFilter;
+}
+
+export interface RelayTaggedFlatFilters {
+  relay: string;
+  filters: Array<FlatReqFilter>;
+}
+
+export interface RelayTaggedFilters {
+  relay: string;
+  filters: Array<ReqFilter>;
+}
+
+/**
+ * Request router managed splitting of requests to one or more relays, and which relay to send events to.
+ */
+export interface RequestRouter {
+  /**
+   * Pick relays to send an event to
+   * @param ev The reply event to send
+   * @param system Nostr system interface
+   * @param pickN Number of relays to pick per recipient
+   * @returns
+   */
+  forReply(ev: NostrEvent, pickN?: number): Promise<Array<string>>;
+
+  /**
+   * Split a request filter to one or more relays.
+   * @param filter Filter to split
+   * @param pickN Number of relays to pick
+   * @returns
+   */
+  forRequest(filter: ReqFilter, pickN?: number): Array<RelayTaggedFilter>;
+
+  /**
+   * Split a request filter to one or more relays.
+   * @param filter Filters to split
+   * @param pickN Number of relays to pick
+   * @returns
+   */
+  forFlatRequest(filter: Array<FlatReqFilter>, pickN?: number): Array<RelayTaggedFlatFilters>;
+}
+
+export abstract class BaseRequestRouter implements RequestRouter {
+  abstract forReply(ev: NostrEvent, pickN?: number): Promise<Array<string>>;
+  abstract forRequest(filter: ReqFilter, pickN?: number): Array<RelayTaggedFilter>;
+  abstract forFlatRequest(filter: FlatReqFilter[], pickN?: number): Array<RelayTaggedFlatFilters>;
+
+  forAllRequest(filters: Array<ReqFilter>) {
+    const allSplit = filters
+      .map(a => this.forRequest(a))
+      .reduce((acc, v) => {
+        for (const vn of v) {
+          const existing = acc.get(vn.relay);
+          if (existing) {
+            existing.push(vn.filter);
+          } else {
+            acc.set(vn.relay, [vn.filter]);
+          }
+        }
+        return acc;
+      }, new Map<string, Array<ReqFilter>>());
+
+    return [...allSplit.entries()].map(([k, v]) => {
+      return {
+        relay: k,
+        filters: v,
+      } as RelayTaggedFilters;
+    });
+  }
+}
diff --git a/packages/system/src/worker/system-worker.ts b/packages/system/src/worker/system-worker.ts
index 9a40e768..8fb0dc8d 100644
--- a/packages/system/src/worker/system-worker.ts
+++ b/packages/system/src/worker/system-worker.ts
@@ -9,7 +9,6 @@ import {
   SystemInterface,
   TaggedNostrEvent,
   CachedMetadata,
-  DefaultOptimizer,
   RelayMetadataLoader,
   RelayMetricCache,
   RelayMetrics,
@@ -17,8 +16,10 @@ import {
   UserRelaysCache,
   UsersRelays,
   QueryLike,
+  Optimizer,
+  DefaultOptimizer,
 } from "..";
-import { NostrSystemEvents, NostrsystemProps } from "../nostr-system";
+import { NostrSystemEvents, SystemConfig } from "../nostr-system";
 import { WorkerCommand, WorkerMessage } from ".";
 import { CachedTable } from "@snort/shared";
 import { EventsCache } from "../cache/events";
@@ -31,38 +32,80 @@ export class SystemWorker extends EventEmitter<NostrSystemEvents> implements Sys
   #log = debug("SystemWorker");
   #worker: Worker;
   #commandQueue: Map<string, (v: unknown) => void> = new Map();
-  readonly relayCache: CachedTable<UsersRelays>;
-  readonly profileCache: CachedTable<CachedMetadata>;
-  readonly relayMetricsCache: CachedTable<RelayMetrics>;
-  readonly profileLoader: ProfileLoaderService;
-  readonly relayMetricsHandler: RelayMetricHandler;
-  readonly eventsCache: CachedTable<NostrEvent>;
-  readonly relayLoader: RelayMetadataLoader;
-  readonly cacheRelay: CacheRelay | undefined;
+  #config: SystemConfig;
 
-  get checkSigs() {
-    return true;
+  /**
+   * Storage class for user relay lists
+   */
+  get relayCache(): CachedTable<UsersRelays> {
+    return this.#config.relays;
+  }
+
+  /**
+   * Storage class for user profiles
+   */
+  get profileCache(): CachedTable<CachedMetadata> {
+    return this.#config.profiles;
+  }
+
+  /**
+   * Storage class for relay metrics (connects/disconnects)
+   */
+  get relayMetricsCache(): CachedTable<RelayMetrics> {
+    return this.#config.relayMetrics;
+  }
+
+  /**
+   * Optimizer instance, contains optimized functions for processing data
+   */
+  get optimizer(): Optimizer {
+    return this.#config.optimizer;
+  }
+
+  get eventsCache(): CachedTable<NostrEvent> {
+    return this.#config.events;
+  }
+
+  /**
+   * Check event signatures (recommended)
+   */
+  get checkSigs(): boolean {
+    return this.#config.checkSigs;
   }
 
   set checkSigs(v: boolean) {
-    // not used
+    this.#config.checkSigs = v;
   }
 
-  get optimizer() {
-    return DefaultOptimizer;
+  get requestRouter() {
+    return undefined;
+  }
+
+  get cacheRelay(): CacheRelay | undefined {
+    return this.#config.cachingRelay;
   }
 
   get pool() {
     return {} as ConnectionPool;
   }
 
-  constructor(scriptPath: string, props: NostrsystemProps) {
-    super();
+  readonly relayLoader: RelayMetadataLoader;
+  readonly profileLoader: ProfileLoaderService;
+  readonly relayMetricsHandler: RelayMetricHandler;
 
-    this.relayCache = props.relayCache ?? new UserRelaysCache(props.db?.userRelays);
-    this.profileCache = props.profileCache ?? new UserProfileCache(props.db?.users);
-    this.relayMetricsCache = props.relayMetrics ?? new RelayMetricCache(props.db?.relayMetrics);
-    this.eventsCache = props.eventsCache ?? new EventsCache(props.db?.events);
+  constructor(scriptPath: string, props: Partial<SystemConfig>) {
+    super();
+    this.#config = {
+      relays: props.relays ?? new UserRelaysCache(props.db?.userRelays),
+      profiles: props.profiles ?? new UserProfileCache(props.db?.users),
+      relayMetrics: props.relayMetrics ?? new RelayMetricCache(props.db?.relayMetrics),
+      events: props.events ?? new EventsCache(props.db?.events),
+      optimizer: props.optimizer ?? DefaultOptimizer,
+      checkSigs: props.checkSigs ?? false,
+      cachingRelay: props.cachingRelay,
+      db: props.db,
+      automaticOutboxModel: props.automaticOutboxModel ?? true,
+    };
 
     this.profileLoader = new ProfileLoaderService(this, this.profileCache);
     this.relayMetricsHandler = new RelayMetricHandler(this.relayMetricsCache);