diff --git a/lib/components/neynar-client-provider.react.js b/lib/components/neynar-client-provider.react.js
--- a/lib/components/neynar-client-provider.react.js
+++ b/lib/components/neynar-client-provider.react.js
@@ -2,10 +2,12 @@
 
 import * as React from 'react';
 
+import { FCCache } from '../utils/fc-cache.js';
 import { NeynarClient } from '../utils/neynar-client.js';
 
 type NeynarClientContextType = {
   +client: NeynarClient,
+  +fcCache: FCCache,
 };
 
 const NeynarClientContext: React.Context<?NeynarClientContextType> =
@@ -31,6 +33,7 @@
     }
     return {
       client: neynarClient,
+      fcCache: new FCCache(neynarClient),
     };
   }, [neynarClient]);
 
diff --git a/lib/types/farcaster-types.js b/lib/types/farcaster-types.js
--- a/lib/types/farcaster-types.js
+++ b/lib/types/farcaster-types.js
@@ -14,13 +14,19 @@
       +fid: string,
     };
 
-export type NeynarUserWithViewerContext = {
+export type NeynarUser = {
   +fid: number,
+  +username: string,
+  ...
+};
+
+export type NeynarUserWithViewerContext = $ReadOnly<{
+  ...NeynarUser,
   +viewerContext: {
     +following: boolean,
   },
   ...
-};
+}>;
 
 export type NeynarChannel = {
   +id: string,
diff --git a/lib/utils/fc-cache.js b/lib/utils/fc-cache.js
new file mode 100644
--- /dev/null
+++ b/lib/utils/fc-cache.js
@@ -0,0 +1,152 @@
+// @flow
+
+import { NeynarClient } from './neynar-client.js';
+import sleep from './sleep.js';
+
+const cacheTimeout = 24 * 60 * 60 * 1000; // one day
+const failedQueryCacheTimeout = 5 * 60 * 1000; // five minutes
+const queryTimeout = 10 * 1000; // ten seconds
+
+async function throwOnTimeout(identifier: string) {
+  await sleep(queryTimeout);
+  throw new Error(`Farcaster fetch for ${identifier} timed out`);
+}
+
+type FarcasterUsernameQueryCacheEntry = {
+  +fid: string,
+  +expirationTime: number,
+  +farcasterUsername: ?string | Promise<?string>,
+};
+
+class FCCache {
+  client: NeynarClient;
+
+  // Maps from FIDs to a cache entry for its Farcaster username
+  farcasterUsernameQueryCache: Map<string, FarcasterUsernameQueryCacheEntry> =
+    new Map();
+
+  constructor(client: NeynarClient) {
+    this.client = client;
+  }
+
+  getFarcasterUsernamesForFIDs(
+    fids: $ReadOnlyArray<string>,
+  ): Promise<Array<?string>> {
+    const cacheMatches = fids.map(fid =>
+      this.getCachedFarcasterUsernameEntryForFID(fid),
+    );
+    const cacheResultsPromise = Promise.all(
+      cacheMatches.map(match =>
+        Promise.resolve(match ? match.farcasterUsername : match),
+      ),
+    );
+    if (cacheMatches.every(Boolean)) {
+      return cacheResultsPromise;
+    }
+
+    const needFetch = [];
+    for (let i = 0; i < fids.length; i++) {
+      const fid = fids[i];
+      const cacheMatch = cacheMatches[i];
+      if (!cacheMatch) {
+        needFetch.push(fid);
+      }
+    }
+
+    const fetchFarcasterUsernamesPromise = (async () => {
+      let farcasterUsernames: $ReadOnlyArray<?string>;
+      try {
+        farcasterUsernames = await Promise.race([
+          this.client.getFarcasterUsernames(needFetch),
+          throwOnTimeout(`usernames for ${JSON.stringify(needFetch)}`),
+        ]);
+      } catch (e) {
+        console.log(e);
+        farcasterUsernames = new Array<?string>(needFetch.length).fill(null);
+      }
+
+      const resultMap = new Map<string, ?string>();
+      for (let i = 0; i < needFetch.length; i++) {
+        const fid = needFetch[i];
+        const farcasterUsername = farcasterUsernames[i];
+        resultMap.set(fid, farcasterUsername);
+      }
+      return resultMap;
+    })();
+
+    for (let i = 0; i < needFetch.length; i++) {
+      const fid = needFetch[i];
+      const fetchFarcasterUsernamePromise = (async () => {
+        const resultMap = await fetchFarcasterUsernamesPromise;
+        return resultMap.get(fid) ?? null;
+      })();
+      this.farcasterUsernameQueryCache.set(fid, {
+        fid,
+        expirationTime: Date.now() + queryTimeout * 2,
+        farcasterUsername: fetchFarcasterUsernamePromise,
+      });
+    }
+
+    return (async () => {
+      const [resultMap, cacheResults] = await Promise.all([
+        fetchFarcasterUsernamesPromise,
+        cacheResultsPromise,
+      ]);
+      for (let i = 0; i < needFetch.length; i++) {
+        const fid = needFetch[i];
+        const farcasterUsername = resultMap.get(fid);
+        const timeout =
+          farcasterUsername === null ? failedQueryCacheTimeout : cacheTimeout;
+        this.farcasterUsernameQueryCache.set(fid, {
+          fid,
+          expirationTime: Date.now() + timeout,
+          farcasterUsername,
+        });
+      }
+
+      const results = [];
+      for (let i = 0; i < fids.length; i++) {
+        const cachedResult = cacheResults[i];
+        if (cachedResult) {
+          results.push(cachedResult);
+        } else {
+          results.push(resultMap.get(fids[i]));
+        }
+      }
+      return results;
+    })();
+  }
+
+  getCachedFarcasterUsernameEntryForFID(
+    fid: string,
+  ): ?FarcasterUsernameQueryCacheEntry {
+    const cacheResult = this.farcasterUsernameQueryCache.get(fid);
+    if (!cacheResult) {
+      return undefined;
+    }
+
+    const { expirationTime } = cacheResult;
+    if (expirationTime <= Date.now()) {
+      this.farcasterUsernameQueryCache.delete(fid);
+      return undefined;
+    }
+
+    return cacheResult;
+  }
+
+  getCachedFarcasterUsernameForFID(fid: string): ?string {
+    const cacheResult = this.getCachedFarcasterUsernameEntryForFID(fid);
+    if (!cacheResult) {
+      return undefined;
+    }
+
+    const { farcasterUsername } = cacheResult;
+    if (typeof farcasterUsername !== 'string') {
+      return undefined;
+    }
+
+    return farcasterUsername;
+  }
+}
+
+export { FCCache };
diff --git a/lib/utils/neynar-client.js b/lib/utils/neynar-client.js
--- a/lib/utils/neynar-client.js
+++ b/lib/utils/neynar-client.js
@@ -5,6 +5,7 @@
 import { getMessageForException } from './errors.js';
 import type {
   NeynarChannel,
+  NeynarUser,
   NeynarUserWithViewerContext,
 } from '../types/farcaster-types.js';
 
@@ -24,6 +25,10 @@
   },
 };
 
+type FetchUsersResponse = {
+  +users: $ReadOnlyArray<NeynarUser>,
+};
+
 const neynarBaseURL = 'https://api.neynar.com/';
 const neynarURLs = {
   '1': `${neynarBaseURL}v1/farcaster/`,
@@ -141,6 +146,47 @@
 
     return farcasterChannels;
   }
+
+  async getFarcasterUsernames(
+    fids: $ReadOnlyArray<string>,
+  ): Promise<Array<?string>> {
+    const fidsLeft = [...fids];
+    const results: Array<?string> = [];
+    do {
+      // Neynar API allows querying 100 at a time
+      const batch = fidsLeft.splice(0, 100);
+      const url = getNeynarURL('2', 'user/bulk', { fids: batch.join(',') });
+      try {
+        const response = await fetch(url, {
+          method: 'GET',
+          headers: {
+            Accept: 'application/json',
+            api_key: this.apiKey,
+          },
+        });
+
+        const json: FetchUsersResponse = await response.json();
+        const { users } = json;
+
+        const neynarUserMap = new Map<number, NeynarUser>();
+        for (const neynarUser of users) {
+          neynarUserMap.set(neynarUser.fid, neynarUser);
+        }
+
+        for (const fid of batch) {
+          const neynarUser = neynarUserMap.get(parseInt(fid));
+          results.push(neynarUser ? neynarUser.username : null);
+        }
+      } catch (error) {
+        console.log(
+          'Failed to fetch Farcaster usernames:',
+          getMessageForException(error) ?? 'unknown',
+        );
+        throw error;
+      }
+    } while (fidsLeft.length > 0);
+    return results;
+  }
 }
 
 export { NeynarClient };