diff --git a/packages/browser-sdk/example/typescript/app.ts b/packages/browser-sdk/example/typescript/app.ts
index 72ee20cd..b06546ab 100644
--- a/packages/browser-sdk/example/typescript/app.ts
+++ b/packages/browser-sdk/example/typescript/app.ts
@@ -1,10 +1,11 @@
-import { BucketClient } from "../../src";
+import { BucketClient, FeatureKey } from "../../src";
+import features from "./bucket.config";
 
 const urlParams = new URLSearchParams(window.location.search);
 const publishableKey = urlParams.get("publishableKey");
-const featureKey = urlParams.get("featureKey") ?? "huddles";
-
-const featureList = ["huddles"];
+const featureKey = (urlParams.get("featureKey") ?? "huddles") as FeatureKey<
+  typeof features
+>;
 
 if (!publishableKey) {
   throw Error("publishableKey is missing");
@@ -18,7 +19,7 @@ const bucket = new BucketClient({
     show: true,
     position: { placement: "bottom-right" },
   },
-  featureList,
+  features,
 });
 
 document
@@ -38,9 +39,14 @@ bucket.initialize().then(() => {
 });
 
 bucket.onFeaturesUpdated(() => {
-  const { isEnabled } = bucket.getFeature("huddles");
+  const { isEnabled, config } = bucket.getFeature("huddles");
 
   const startHuddleElem = document.getElementById("start-huddle");
+  if (startHuddleElem) {
+    startHuddleElem.innerText =
+      config?.payload?.startHuddleCopy ?? "Start Huddle";
+  }
+
   if (isEnabled) {
     // show the start-huddle button
     if (startHuddleElem) startHuddleElem.style.display = "block";
diff --git a/packages/browser-sdk/example/typescript/bucket.config.ts b/packages/browser-sdk/example/typescript/bucket.config.ts
new file mode 100644
index 00000000..515d7ba2
--- /dev/null
+++ b/packages/browser-sdk/example/typescript/bucket.config.ts
@@ -0,0 +1,7 @@
+import { defineFeatures } from "../../src";
+
+export default defineFeatures([
+  "feature1",
+  "feature2",
+  { key: "huddles", config: { startHuddleCopy: "string" } },
+]);
diff --git a/packages/browser-sdk/example/typescript/index.html b/packages/browser-sdk/example/typescript/index.html
index cec72d21..ec4f2fc7 100644
--- a/packages/browser-sdk/example/typescript/index.html
+++ b/packages/browser-sdk/example/typescript/index.html
@@ -14,7 +14,7 @@
       }
     </style>
     <div id="start-huddle" style="display: none">
-      Start huddle!<br />
+      <span id="start-huddle-copy">Start huddle!</span><br />
       <button id="startHuddle">Click me</button>
       <button id="giveFeedback">Give feedback!</button>
     </div>
diff --git a/packages/browser-sdk/src/client.ts b/packages/browser-sdk/src/client.ts
index eb7488f6..91c1b458 100644
--- a/packages/browser-sdk/src/client.ts
+++ b/packages/browser-sdk/src/client.ts
@@ -15,8 +15,13 @@ import {
 } from "./feedback/feedback";
 import * as feedbackLib from "./feedback/ui";
 import { ToolbarPosition } from "./toolbar/Toolbar";
-import { API_BASE_URL, APP_BASE_URL, SSE_REALTIME_BASE_URL } from "./config";
+import { API_BASE_URL, APP_BASE_URL, SSE_REALTIME_BASE_URL } from "./constants";
 import { BucketContext, CompanyContext, UserContext } from "./context";
+import {
+  ConfigType,
+  FeatureDefinitions,
+  FeatureKey,
+} from "./featureDefinitions";
 import { HttpClient } from "./httpClient";
 import { Logger, loggerWithPrefix, quietConsoleLogger } from "./logger";
 import { showToolbarToggle } from "./toolbar";
@@ -177,15 +182,10 @@ export type ToolbarOptions =
       position?: ToolbarPosition;
     };
 
-/**
- * Feature definitions.
- */
-export type FeatureDefinitions = Readonly<Array<string>>;
-
 /**
  * BucketClient initialization options.
  */
-export type InitOptions = {
+export type InitOptions<TFeatures extends FeatureDefinitions = any> = {
   /**
    * Publishable key for authentication
    */
@@ -284,7 +284,7 @@ export type InitOptions = {
   /**
    * Local-first definition of features
    */
-  features?: FeatureDefinitions;
+  features?: TFeatures;
 };
 
 const defaultConfig: Config = {
@@ -294,27 +294,10 @@ const defaultConfig: Config = {
   enableTracking: true,
 };
 
-/**
- * A remotely managed configuration value for a feature.
- */
-export type FeatureRemoteConfig =
-  | {
-      /**
-       * The key of the matched configuration value.
-       */
-      key: string;
-
-      /**
-       * The optional user-supplied payload data.
-       */
-      payload: any;
-    }
-  | { key: undefined; payload: undefined };
-
 /**
  * A feature.
  */
-export interface Feature {
+export interface Feature<TRemoteConfig = any> {
   /**
    * Result of feature flag evaluation.
    */
@@ -323,7 +306,19 @@ export interface Feature {
   /*
    * Optional user-defined configuration.
    */
-  config: FeatureRemoteConfig;
+  config:
+    | {
+        /**
+         * The key of the matched configuration value.
+         */
+        key: string;
+
+        /**
+         * The optional user-supplied payload data.
+         */
+        payload: TRemoteConfig;
+      }
+    | { key: undefined; payload: undefined };
 
   /**
    * Function to send analytics events for this feature.
@@ -338,7 +333,7 @@ export interface Feature {
   ) => void;
 }
 
-function shouldShowToolbar(opts: InitOptions) {
+function shouldShowToolbar(opts: InitOptions<any>) {
   const toolbarOpts = opts.toolbar;
   if (typeof toolbarOpts === "boolean") return toolbarOpts;
   if (typeof toolbarOpts?.show === "boolean") return toolbarOpts.show;
@@ -351,7 +346,10 @@ function shouldShowToolbar(opts: InitOptions) {
 /**
  * BucketClient lets you interact with the Bucket API.
  */
-export class BucketClient {
+export class BucketClient<
+  TFeatures extends FeatureDefinitions = any,
+  TFeatureKey extends string = FeatureKey<TFeatures>,
+> {
   private readonly publishableKey: string;
   private readonly context: BucketContext;
   private config: Config;
@@ -367,7 +365,7 @@ export class BucketClient {
   /**
    * Create a new BucketClient instance.
    */
-  constructor(opts: InitOptions) {
+  constructor(opts: InitOptions<TFeatures>) {
     this.publishableKey = opts.publishableKey;
     this.logger =
       opts?.logger ?? loggerWithPrefix(quietConsoleLogger, "[Bucket]");
@@ -396,6 +394,9 @@ export class BucketClient {
       sdkVersion: opts?.sdkVersion,
     });
 
+    const keys =
+      opts.features?.map((f) => (f instanceof Object ? f.key : f)) ?? [];
+
     this.featuresClient = new FeaturesClient(
       this.httpClient,
       // API expects `other` and we have `otherContext`.
@@ -404,7 +405,7 @@ export class BucketClient {
         company: this.context.company,
         other: this.context.otherContext,
       },
-      opts?.features || [],
+      keys,
       this.logger,
       {
         expireTimeMs: opts.expireTimeMs,
@@ -614,7 +615,7 @@ export class BucketClient {
    *
    * @param options
    */
-  requestFeedback(options: RequestFeedbackData) {
+  requestFeedback(options: RequestFeedbackData<FeatureKey<TFeatures>>) {
     if (!this.context.user?.id) {
       this.logger.error(
         "`requestFeedback` call ignored. No `user` context provided at initialization",
@@ -692,7 +693,9 @@ export class BucketClient {
    * Return a feature. Accessing `isEnabled` or `config` will automatically send a `check` event.
    * @returns A feature.
    */
-  getFeature(key: string): Feature {
+  getFeature<TKey extends TFeatureKey>(
+    key: TKey,
+  ): Feature<ConfigType<TFeatures, TKey>> {
     const f = this.getFeatures()[key];
 
     const fClient = this.featuresClient;
diff --git a/packages/browser-sdk/src/config.ts b/packages/browser-sdk/src/constants.ts
similarity index 100%
rename from packages/browser-sdk/src/config.ts
rename to packages/browser-sdk/src/constants.ts
diff --git a/packages/browser-sdk/src/feature/features.ts b/packages/browser-sdk/src/feature/features.ts
index cd536e5d..07da92e4 100644
--- a/packages/browser-sdk/src/feature/features.ts
+++ b/packages/browser-sdk/src/feature/features.ts
@@ -1,4 +1,4 @@
-import { FEATURE_EVENTS_PER_MIN } from "../config";
+import { FEATURE_EVENTS_PER_MIN } from "../constants";
 import { HttpClient } from "../httpClient";
 import { Logger, loggerWithPrefix } from "../logger";
 import RateLimiter from "../rateLimiter";
diff --git a/packages/browser-sdk/src/featureDefinitions.ts b/packages/browser-sdk/src/featureDefinitions.ts
new file mode 100644
index 00000000..2d2d97de
--- /dev/null
+++ b/packages/browser-sdk/src/featureDefinitions.ts
@@ -0,0 +1,41 @@
+export type ConfigDataType =
+  | "string"
+  | "number"
+  | "boolean"
+  | { [key: string]: ConfigDataType };
+
+export type FeatureDefinitions = Readonly<
+  Array<string | { key: string; config?: ConfigDataType }>
+>;
+
+export type StringTypeToTSType<C extends ConfigDataType> = C extends "string"
+  ? string
+  : C extends "number"
+    ? number
+    : C extends "boolean"
+      ? boolean
+      : C extends { [key: string]: ConfigDataType }
+        ? { [K in keyof C]: StringTypeToTSType<C[K]> }
+        : never;
+
+export type ConfigType<Defs extends FeatureDefinitions, Key extends string> =
+  Extract<Defs[number], { key: Key; config: any }> extends never
+    ? undefined
+    : StringTypeToTSType<
+        Extract<Defs[number], { key: Key; config: any }>["config"]
+      >;
+
+export type FeatureKey<Defs extends FeatureDefinitions> =
+  | Extract<Defs[number], string>
+  | Extract<Defs[number], { key: string }>["key"];
+
+/**
+ * Define features for the SDK
+ * @param features Feature definitions
+ * @returns Feature definitions, ready to plug into the SDK
+ */
+export function defineFeatures<const TFeatures extends FeatureDefinitions>(
+  features: TFeatures,
+): TFeatures {
+  return features;
+}
diff --git a/packages/browser-sdk/src/feedback/feedback.ts b/packages/browser-sdk/src/feedback/feedback.ts
index 3e70bd74..dec3c2df 100644
--- a/packages/browser-sdk/src/feedback/feedback.ts
+++ b/packages/browser-sdk/src/feedback/feedback.ts
@@ -69,7 +69,7 @@ export function handleDeprecatedFeedbackOptions(
   };
 }
 
-export type RequestFeedbackData = Omit<
+export type RequestFeedbackData<TFeatureKey extends string = string> = Omit<
   OpenFeedbackFormOptions,
   "key" | "onSubmit"
 > & {
@@ -93,7 +93,7 @@ export type RequestFeedbackData = Omit<
   /**
    * Bucket feature key.
    */
-  featureKey: string;
+  featureKey: TFeatureKey;
 };
 
 export type RequestFeedbackOptions = RequestFeedbackData & {
diff --git a/packages/browser-sdk/src/httpClient.ts b/packages/browser-sdk/src/httpClient.ts
index 43c925f8..ce91b596 100644
--- a/packages/browser-sdk/src/httpClient.ts
+++ b/packages/browser-sdk/src/httpClient.ts
@@ -1,4 +1,4 @@
-import { API_BASE_URL, SDK_VERSION, SDK_VERSION_HEADER_NAME } from "./config";
+import { API_BASE_URL, SDK_VERSION, SDK_VERSION_HEADER_NAME } from "./constants";
 
 export interface HttpClientOptions {
   baseUrl?: string;
diff --git a/packages/browser-sdk/src/index.ts b/packages/browser-sdk/src/index.ts
index a1044228..499bf1b4 100644
--- a/packages/browser-sdk/src/index.ts
+++ b/packages/browser-sdk/src/index.ts
@@ -7,6 +7,12 @@ export type {
   RawFeature,
   RawFeatures,
 } from "./feature/features";
+export type {
+  ConfigType,
+  FeatureDefinitions,
+  FeatureKey,
+} from "./featureDefinitions";
+export { defineFeatures } from "./featureDefinitions";
 export type {
   Feedback,
   FeedbackOptions,
diff --git a/packages/browser-sdk/test/e2e/acceptance.browser.spec.ts b/packages/browser-sdk/test/e2e/acceptance.browser.spec.ts
index 1fc5e8c6..41cedcbf 100644
--- a/packages/browser-sdk/test/e2e/acceptance.browser.spec.ts
+++ b/packages/browser-sdk/test/e2e/acceptance.browser.spec.ts
@@ -1,7 +1,7 @@
 import { randomUUID } from "crypto";
 import { expect, test } from "@playwright/test";
 
-import { API_BASE_URL } from "../../src/config";
+import { API_BASE_URL } from "../../src/constants";
 
 const KEY = randomUUID();
 
diff --git a/packages/browser-sdk/test/features.test.ts b/packages/browser-sdk/test/features.test.ts
index b0282fe0..d8360e64 100644
--- a/packages/browser-sdk/test/features.test.ts
+++ b/packages/browser-sdk/test/features.test.ts
@@ -1,13 +1,13 @@
 import { afterAll, beforeEach, describe, expect, test, vi } from "vitest";
 
 import { version } from "../package.json";
-import { FeatureDefinitions } from "../src/client";
 import {
   FEATURES_EXPIRE_MS,
   FeaturesClient,
   FetchedFeature,
   RawFeature,
 } from "../src/feature/features";
+import { FeatureDefinitions } from "../src/featureDefinitions";
 import { HttpClient } from "../src/httpClient";
 
 import { featuresResult } from "./mocks/handlers";
@@ -48,7 +48,7 @@ function featuresClientFactory() {
           other: { eventId: "big-conference1" },
           ...context,
         },
-        features || [],
+        features?.map((f) => (f instanceof Object ? f.key : f)) || [],
         testLogger,
         {
           cache,
diff --git a/packages/browser-sdk/test/usage.test.ts b/packages/browser-sdk/test/usage.test.ts
index b792fdb2..3ffbc293 100644
--- a/packages/browser-sdk/test/usage.test.ts
+++ b/packages/browser-sdk/test/usage.test.ts
@@ -11,7 +11,7 @@ import {
 } from "vitest";
 
 import { BucketClient } from "../src";
-import { API_BASE_URL } from "../src/config";
+import { API_BASE_URL } from "../src/constants";
 import { FeaturesClient } from "../src/feature/features";
 import { FeedbackPromptHandler } from "../src/feedback/feedback";
 import {
diff --git a/packages/react-sdk/dev/plain/app.tsx b/packages/react-sdk/dev/plain/app.tsx
index 3890fa63..7ce5a81b 100644
--- a/packages/react-sdk/dev/plain/app.tsx
+++ b/packages/react-sdk/dev/plain/app.tsx
@@ -10,20 +10,14 @@ import {
   useUpdateOtherContext,
   useUpdateUser,
 } from "../../src";
-
-// Extending the Features interface to define the available features
-declare module "../../src" {
-  interface Features {
-    huddles: boolean;
-  }
-}
+import bucketFeatures from "./bucket.features";
 
 const publishableKey = import.meta.env.VITE_PUBLISHABLE_KEY || "";
 const apiBaseUrl = import.meta.env.VITE_BUCKET_API_BASE_URL;
 
 function HuddleFeature() {
-  // Type safe feature
   const feature = useFeature("huddles");
+
   return (
     <div>
       <h2>Huddle feature</h2>
@@ -148,7 +142,7 @@ function Feedback() {
         onClick={(e) =>
           requestFeedback({
             title: "How do you like Huddles?",
-            featureKey: "huddle",
+            featureKey: "huddles",
             position: {
               type: "POPOVER",
               anchor: e.currentTarget as HTMLElement,
@@ -164,20 +158,26 @@ function Feedback() {
 
 // App.tsx
 function Demos() {
+  const { isEnabled, config } = useFeature("optIn");
+
   return (
     <main>
       <h1>React SDK</h1>
 
       <HuddleFeature />
 
-      <h2>Feature opt-in</h2>
-      <div>
-        Create a <code>huddle</code> feature and set a rule:{" "}
-        <code>optin-huddles IS TRUE</code>. Hit the checkbox below to opt-in/out
-        of the feature.
-      </div>
-      <FeatureOptIn featureKey={"huddles"} featureName={"Huddles"} />
-
+      {isEnabled && (
+        <>
+          <h2>Feature opt-in</h2>
+          <div>
+            Create a <code>huddle</code> feature and set a rule:{" "}
+            <code>optin-huddles IS TRUE</code>. Hit the checkbox below to
+            opt-in/out of the feature.
+            {config.payload?.additionalCopy}
+          </div>
+          <FeatureOptIn featureKey={"huddles"} featureName={"Huddles"} />
+        </>
+      )}
       <UpdateContext />
       <Feedback />
       <SendEvent />
@@ -228,6 +228,7 @@ export function App() {
       user={initialUser}
       otherContext={initialOtherContext}
       apiBaseUrl={apiBaseUrl}
+      features={bucketFeatures}
     >
       <Demos />
       {}
diff --git a/packages/react-sdk/dev/plain/bucket.d.ts b/packages/react-sdk/dev/plain/bucket.d.ts
new file mode 100644
index 00000000..6bffbc6c
--- /dev/null
+++ b/packages/react-sdk/dev/plain/bucket.d.ts
@@ -0,0 +1,6 @@
+import { FeaturesType } from "../../src";
+import features from "./bucket.features";
+
+declare module "../../src" {
+  interface Features extends FeaturesType<typeof features> {}
+}
diff --git a/packages/react-sdk/dev/plain/bucket.features.ts b/packages/react-sdk/dev/plain/bucket.features.ts
new file mode 100644
index 00000000..9bc76e94
--- /dev/null
+++ b/packages/react-sdk/dev/plain/bucket.features.ts
@@ -0,0 +1,10 @@
+import { defineFeatures } from "../../src";
+
+export default defineFeatures([
+  "huddles",
+  "voiceMessages",
+  {
+    key: "optIn",
+    config: { additionalCopy: "string" },
+  },
+] as const);
diff --git a/packages/react-sdk/src/index.tsx b/packages/react-sdk/src/index.tsx
index caad7eaa..df4b68a3 100644
--- a/packages/react-sdk/src/index.tsx
+++ b/packages/react-sdk/src/index.tsx
@@ -10,9 +10,13 @@ import React, {
 } from "react";
 import canonicalJSON from "canonical-json";
 
+import type { FeatureDefinitions } from "@bucketco/browser-sdk";
 import {
   BucketClient,
   BucketContext,
+  ConfigType,
+  defineFeatures,
+  FeatureKey as BaseFeatureKey,
   FeedbackOptions,
   RawFeatures,
   RequestFeedbackData,
@@ -22,6 +26,12 @@ import {
 
 import { version } from "../package.json";
 
+export { defineFeatures, FeatureDefinitions };
+
+export type FeaturesType<TFeatures extends FeatureDefinitions> = {
+  [K in BaseFeatureKey<TFeatures>]: ConfigType<TFeatures, K>;
+};
+
 export interface Features {}
 
 const SDK_VERSION = `react-sdk/${version}`;
@@ -65,7 +75,7 @@ export type BucketProps = BucketContext & {
   debug?: boolean;
   enableTracking?: boolean;
 
-  features?: Readonly<string[]>;
+  features?: Readonly<FeatureDefinitions>;
 
   fallbackFeatures?: FeatureKey[] | Record<FeatureKey, any>;
 
@@ -306,7 +316,8 @@ export function useTrack() {
  */
 export function useRequestFeedback() {
   const { client } = useContext<ProviderContextType>(ProviderContext);
-  return (options: RequestFeedbackData) => client?.requestFeedback(options);
+  return (options: RequestFeedbackData<FeatureKey>) =>
+    client?.requestFeedback(options);
 }
 
 /**