diff --git a/.github/workflows/browser.yml b/.github/workflows/browser.yml
index 6e24d4ec0c..c121998d80 100644
--- a/.github/workflows/browser.yml
+++ b/.github/workflows/browser.yml
@@ -50,6 +50,9 @@ jobs:
       - name: Install Playwright browsers
         run: yarn workspace browser-contract-test-service install-playwright-browsers
 
+      - name: Build shared contract test utils
+        run: yarn workspace @launchdarkly/js-contract-test-utils build:client
+
       - name: Build contract test adapter
         run: yarn workspace browser-contract-test-adapter run build
 
diff --git a/.github/workflows/electron.yaml b/.github/workflows/electron.yaml
index 90dd0e74f7..4a5b5aac00 100644
--- a/.github/workflows/electron.yaml
+++ b/.github/workflows/electron.yaml
@@ -40,6 +40,7 @@ jobs:
           ELECTRON_DISABLE_SANDBOX: '1'
         run: |
           yarn workspaces focus @internal/electron-contract-tests-entity
+          yarn workspace @launchdarkly/js-contract-test-utils build:client
           yarn workspace @internal/electron-contract-tests-entity build
           sudo apt-get install -y xvfb
           Xvfb :99 -screen 0 1024x768x24 > /tmp/xvfb.log 2>&1 &
diff --git a/.github/workflows/react-native-contract-tests.yml b/.github/workflows/react-native-contract-tests.yml
index 687c965736..fb6265b82c 100644
--- a/.github/workflows/react-native-contract-tests.yml
+++ b/.github/workflows/react-native-contract-tests.yml
@@ -33,6 +33,9 @@ jobs:
       - name: Build SDK and dependencies
         run: yarn workspaces foreach -pR --topological-dev --from '@launchdarkly/react-native-client-sdk' run build
 
+      - name: Build shared contract test utils
+        run: yarn workspace @launchdarkly/js-contract-test-utils build:client
+
       - name: Build contract test adapter
         run: yarn workspace react-native-contract-test-adapter run build
 
diff --git a/.github/workflows/react.yaml b/.github/workflows/react.yaml
index 366f40e2af..4766d60a7f 100644
--- a/.github/workflows/react.yaml
+++ b/.github/workflows/react.yaml
@@ -39,8 +39,7 @@ jobs:
           yarn workspaces foreach -pR --topological-dev --from "@launchdarkly/react-sdk-contract-tests" install
           yarn workspaces foreach -pR --topological-dev --from 'browser-contract-test-adapter' run build
           yarn workspaces foreach -pR --topological-dev --from "@launchdarkly/react-sdk-contract-tests" run build
-      - name: Install Playwright browsers
-        run: yarn workspace @launchdarkly/react-sdk-contract-tests install-playwright-browsers
+          yarn workspace @launchdarkly/react-sdk-contract-tests install-playwright-browsers
       - name: Run test adapter
         run: |
           yarn workspace @launchdarkly/react-sdk-contract-tests run start:adapter > /tmp/adapter.log 2>&1 &
diff --git a/.github/workflows/server-node.yml b/.github/workflows/server-node.yml
index 46c225f8fd..85abb74a32 100644
--- a/.github/workflows/server-node.yml
+++ b/.github/workflows/server-node.yml
@@ -33,6 +33,8 @@ jobs:
           workspace_path: packages/sdk/server-node
       - name: Install contract test service dependencies
         run: yarn workspace node-server-sdk-contract-tests install --no-immutable
+      - name: Build shared contract test utils (server)
+        run: yarn workspace @launchdarkly/js-contract-test-utils build:server
       - name: Build the test service
         run: yarn workspace node-server-sdk-contract-tests build
       - name: Launch the test service in the background
diff --git a/.github/workflows/shopify-oxygen.yml b/.github/workflows/shopify-oxygen.yml
index 9eabf2c6dc..26c224b809 100644
--- a/.github/workflows/shopify-oxygen.yml
+++ b/.github/workflows/shopify-oxygen.yml
@@ -28,6 +28,8 @@ jobs:
           workspace_path: packages/sdk/shopify-oxygen
       - name: Install contract test service dependencies
         run: yarn workspace @launchdarkly/shopify-oxygen-contract-tests install --no-immutable
+      - name: Build shared contract test utils
+        run: yarn workspace @launchdarkly/js-contract-test-utils build:server
       - name: Build the test service
         run: yarn workspace @launchdarkly/shopify-oxygen-contract-tests build
       - name: Launch the test service in the background
diff --git a/packages/sdk/server-node/contract-tests/package.json b/packages/sdk/server-node/contract-tests/package.json
index 2b00e78f3f..061721a5b6 100644
--- a/packages/sdk/server-node/contract-tests/package.json
+++ b/packages/sdk/server-node/contract-tests/package.json
@@ -12,6 +12,7 @@
   "license": "Apache-2.0",
   "private": true,
   "dependencies": {
+    "@launchdarkly/js-contract-test-utils": "workspace:^",
     "@launchdarkly/node-server-sdk": "workspace:^",
     "body-parser": "^1.19.0",
     "express": "^4.17.1",
diff --git a/packages/sdk/server-node/contract-tests/src/TestHook.ts b/packages/sdk/server-node/contract-tests/src/TestHook.ts
deleted file mode 100644
index abad14331d..0000000000
--- a/packages/sdk/server-node/contract-tests/src/TestHook.ts
+++ /dev/null
@@ -1,75 +0,0 @@
-import got from 'got';
-
-import { integrations, LDEvaluationDetail } from '@launchdarkly/node-server-sdk';
-
-export interface HookData {
-  beforeEvaluation?: Record<string, unknown>;
-  afterEvaluation?: Record<string, unknown>;
-}
-
-export interface HookErrors {
-  beforeEvaluation?: string;
-  afterEvaluation?: string;
-}
-
-export default class TestHook implements integrations.Hook {
-  private _name: string;
-  private _endpoint: string;
-  private _data?: HookData;
-  private _errors?: HookErrors;
-
-  constructor(name: string, endpoint: string, data?: HookData, errors?: HookErrors) {
-    this._name = name;
-    this._endpoint = endpoint;
-    this._data = data;
-    this._errors = errors;
-  }
-
-  private async _safePost(body: unknown): Promise<void> {
-    try {
-      await got.post(this._endpoint, { json: body });
-    } catch {
-      // The test could move on before the post, so we are ignoring
-      // failed posts.
-    }
-  }
-
-  getMetadata(): integrations.HookMetadata {
-    return {
-      name: this._name,
-    };
-  }
-
-  beforeEvaluation(
-    hookContext: integrations.EvaluationSeriesContext,
-    data: integrations.EvaluationSeriesData,
-  ): integrations.EvaluationSeriesData {
-    if (this._errors?.beforeEvaluation) {
-      throw new Error(this._errors.beforeEvaluation);
-    }
-    this._safePost({
-      evaluationSeriesContext: hookContext,
-      evaluationSeriesData: data,
-      stage: 'beforeEvaluation',
-    });
-    return { ...data, ...(this._data?.beforeEvaluation || {}) };
-  }
-
-  afterEvaluation(
-    hookContext: integrations.EvaluationSeriesContext,
-    data: integrations.EvaluationSeriesData,
-    detail: LDEvaluationDetail,
-  ): integrations.EvaluationSeriesData {
-    if (this._errors?.afterEvaluation) {
-      throw new Error(this._errors.afterEvaluation);
-    }
-    this._safePost({
-      evaluationSeriesContext: hookContext,
-      evaluationSeriesData: data,
-      stage: 'afterEvaluation',
-      evaluationDetail: detail,
-    });
-
-    return { ...data, ...(this._data?.afterEvaluation || {}) };
-  }
-}
diff --git a/packages/sdk/server-node/contract-tests/src/index.ts b/packages/sdk/server-node/contract-tests/src/index.ts
index f366bf9ca4..8265479343 100644
--- a/packages/sdk/server-node/contract-tests/src/index.ts
+++ b/packages/sdk/server-node/contract-tests/src/index.ts
@@ -2,6 +2,8 @@ import bodyParser from 'body-parser';
 import express, { Request, Response } from 'express';
 import { Server } from 'http';
 
+import { ClientPool } from '@launchdarkly/js-contract-test-utils/server';
+
 import { Log } from './log.js';
 import { badCommandError, newSdkClientEntity, SdkClientEntity } from './sdkClientEntity.js';
 
@@ -10,8 +12,7 @@ let server: Server | null = null;
 
 const port = 8000;
 
-let clientCounter = 0;
-const clients: Record<string, SdkClientEntity> = {};
+const clients = new ClientPool<SdkClientEntity>();
 
 const mainLog = Log('service');
 
@@ -66,16 +67,12 @@ app.delete('/', (req: Request, res: Response) => {
 app.post('/', async (req: Request, res: Response) => {
   const options = req.body;
 
-  clientCounter += 1;
-  const clientId = clientCounter.toString();
-  const resourceUrl = `/clients/${clientId}`;
-
   try {
     const client = await newSdkClientEntity(options);
-    clients[clientId] = client;
+    const clientId = clients.add(client);
 
     res.status(201);
-    res.set('Location', resourceUrl);
+    res.set('Location', `/clients/${clientId}`);
   } catch (e) {
     res.status(500);
     const message = e instanceof Error ? e.message : JSON.stringify(e);
@@ -86,7 +83,7 @@ app.post('/', async (req: Request, res: Response) => {
 });
 
 app.post('/clients/:id', async (req: Request, res: Response) => {
-  const client = clients[req.params.id];
+  const client = clients.get(req.params.id);
   if (!client) {
     res.status(404);
   } else {
@@ -113,13 +110,13 @@ app.post('/clients/:id', async (req: Request, res: Response) => {
 });
 
 app.delete('/clients/:id', async (req: Request, res: Response) => {
-  const client = clients[req.params.id];
+  const client = clients.get(req.params.id);
   if (!client) {
     res.status(404);
     res.send();
   } else {
     client.close();
-    delete clients[req.params.id];
+    clients.remove(req.params.id);
     res.status(204);
     res.send();
   }
diff --git a/packages/sdk/server-node/contract-tests/src/sdkClientEntity.ts b/packages/sdk/server-node/contract-tests/src/sdkClientEntity.ts
index f1fcfabe2b..2b99380531 100644
--- a/packages/sdk/server-node/contract-tests/src/sdkClientEntity.ts
+++ b/packages/sdk/server-node/contract-tests/src/sdkClientEntity.ts
@@ -1,5 +1,11 @@
 import got from 'got';
 
+import {
+  CommandParams,
+  CreateInstanceParams,
+  ServerSDKConfigParams,
+  ServerSideTestHook as TestHook,
+} from '@launchdarkly/js-contract-test-utils/server';
 import ld, {
   createMigration,
   DataSourceOptions,
@@ -7,7 +13,6 @@ import ld, {
   LDConcurrentExecution,
   LDContext,
   LDExecutionOrdering,
-  LDFlagValue,
   LDMigrationError,
   LDMigrationStage,
   LDMigrationSuccess,
@@ -20,136 +25,11 @@ import ld, {
 
 import BigSegmentTestStore from './BigSegmentTestStore.js';
 import { Log, sdkLogger } from './log.js';
-import TestHook from './TestHook.js';
 
 const badCommandError = new Error('unsupported command');
 export { badCommandError };
 
-interface SdkConfigOptions {
-  streaming?: {
-    baseUri: string;
-    initialRetryDelayMs?: number;
-    filter?: string;
-  };
-  polling?: {
-    baseUri: string;
-    pollIntervalMs: number;
-    filter?: string;
-  };
-  dataSystem?: {
-    initializers?: SDKDataSystemInitializerParams[];
-    synchronizers?: SDKDataSystemSynchronizerParams[];
-    payloadFilter?: string;
-  };
-  events?: {
-    allAttributesPrivate?: boolean;
-    baseUri: string;
-    capacity?: number;
-    enableDiagnostics?: boolean;
-    flushIntervalMs?: number;
-    globalPrivateAttributes?: string[];
-    enableGzip?: boolean;
-  };
-  tags?: {
-    applicationId: string;
-    applicationVersion: string;
-  };
-  bigSegments?: {
-    callbackUri: string;
-    userCacheSize?: number;
-    userCacheTimeMs?: number;
-    statusPollIntervalMs?: number;
-    staleAfterMs?: number;
-  };
-  hooks?: {
-    hooks: {
-      name: string;
-      callbackUri: string;
-      data: any;
-      errors: any;
-    }[];
-  };
-  wrapper?: {
-    name?: string;
-    version?: string;
-  };
-}
-
-export interface SDKDataSystemSynchronizerParams {
-  streaming?: SDKDataSourceStreamingParams;
-  polling?: SDKDataSourcePollingParams;
-}
-
-export interface SDKDataSystemInitializerParams {
-  polling?: SDKDataSourcePollingParams;
-}
-
-export interface SDKDataSourceStreamingParams {
-  baseUri?: string;
-  initialRetryDelayMs?: number;
-}
-
-export interface SDKDataSourcePollingParams {
-  baseUri?: string;
-  pollIntervalMs?: number;
-}
-
-interface CommandParams {
-  command: string;
-  evaluate?: {
-    flagKey: string;
-    context?: LDContext;
-    user?: LDUser;
-    defaultValue: LDFlagValue;
-    detail?: boolean;
-    valueType?: string;
-  };
-  evaluateAll?: {
-    context?: LDContext;
-    user?: LDUser;
-    clientSideOnly?: boolean;
-    detailsOnlyForTrackedFlags?: boolean;
-    withReasons?: boolean;
-  };
-  identifyEvent?: {
-    context?: LDContext;
-    user?: LDUser;
-  };
-  customEvent?: {
-    eventKey: string;
-    context?: LDContext;
-    user?: LDUser;
-    data?: any;
-    metricValue?: number;
-  };
-  migrationVariation?: {
-    key: string;
-    context: LDContext;
-    defaultStage: LDMigrationStage;
-  };
-  migrationOperation?: {
-    operation: string;
-    key: string;
-    context: LDContext;
-    defaultStage: LDMigrationStage;
-    payload: any;
-    readExecutionOrder: string;
-    trackLatency?: boolean;
-    trackErrors?: boolean;
-    trackConsistency?: boolean;
-    newEndpoint: string;
-    oldEndpoint: string;
-  };
-  registerFlagChangeListener?: {
-    listenerId: string;
-    callbackUri: string;
-  };
-  unregisterListener?: {
-    listenerId: string;
-  };
-}
-
-export function makeSdkConfig(options: SdkConfigOptions, tag: string): LDOptions {
+export function makeSdkConfig(options: ServerSDKConfigParams, tag: string): LDOptions {
   const cf: LDOptions = {
     logger: sdkLogger(tag),
     diagnosticOptOut: true,
@@ -169,7 +49,7 @@ export function makeSdkConfig(options: SdkConfigOptions, tag: string): LDOptions
   if (options.polling) {
     cf.stream = false;
     cf.baseUri = options.polling.baseUri;
-    cf.pollInterval = options.polling.pollIntervalMs / 1000;
+    cf.pollInterval = maybeTime(options.polling.pollIntervalMs);
     if (options.polling.filter) {
       cf.payloadFilterKey = options.polling.filter;
     }
@@ -312,10 +192,14 @@ function makeMigrationPostOptions(payload: any) {
 }
 
 function contextOrUser(
-  context: LDContext | undefined,
+  context: Record<string, any> | undefined,
   user: LDUser | undefined,
 ): LDContext | LDUser {
-  return (context || user)!;
+  const result = (context as LDContext | undefined) ?? user;
+  if (!result) {
+    throw new Error('Neither context nor user provided');
+  }
+  return result;
 }
 
 export interface SdkClientEntity {
@@ -328,7 +212,7 @@ interface ListenerEntry {
   handler: (...args: any[]) => void;
 }
 
-export async function newSdkClientEntity(options: any): Promise<SdkClientEntity> {
+export async function newSdkClientEntity(options: CreateInstanceParams): Promise<SdkClientEntity> {
   const c: any = {};
   const log = Log(options.tag);
   const listeners = new Map<string, ListenerEntry>();
@@ -341,7 +225,7 @@ export async function newSdkClientEntity(options: any): Promise<SdkClientEntity>
       : 5000;
   const client: LDClient = ld.init(
     options.configuration.credential || 'unknown-sdk-key',
-    makeSdkConfig(options.configuration, options.tag),
+    makeSdkConfig(options.configuration as ServerSDKConfigParams, options.tag),
   );
   try {
     await client.waitForInitialization({ timeout });
@@ -372,12 +256,12 @@ export async function newSdkClientEntity(options: any): Promise<SdkClientEntity>
         if (pe.detail) {
           switch (pe.valueType) {
             case 'bool':
-              return client.boolVariationDetail(pe.flagKey, context, pe.defaultValue);
+              return client.boolVariationDetail(pe.flagKey, context, pe.defaultValue as boolean);
             case 'int': // Intentional fallthrough.
             case 'double':
-              return client.numberVariationDetail(pe.flagKey, context, pe.defaultValue);
+              return client.numberVariationDetail(pe.flagKey, context, pe.defaultValue as number);
             case 'string':
-              return client.stringVariationDetail(pe.flagKey, context, pe.defaultValue);
+              return client.stringVariationDetail(pe.flagKey, context, pe.defaultValue as string);
             default:
               return client.variationDetail(
                 pe.flagKey,
@@ -389,16 +273,16 @@ export async function newSdkClientEntity(options: any): Promise<SdkClientEntity>
           switch (pe.valueType) {
             case 'bool':
               return {
-                value: await client.boolVariation(pe.flagKey, context, pe.defaultValue),
+                value: await client.boolVariation(pe.flagKey, context, pe.defaultValue as boolean),
               };
             case 'int': // Intentional fallthrough.
             case 'double':
               return {
-                value: await client.numberVariation(pe.flagKey, context, pe.defaultValue),
+                value: await client.numberVariation(pe.flagKey, context, pe.defaultValue as number),
               };
             case 'string':
               return {
-                value: await client.stringVariation(pe.flagKey, context, pe.defaultValue),
+                value: await client.stringVariation(pe.flagKey, context, pe.defaultValue as string),
               };
             default:
               return {
@@ -419,7 +303,9 @@ export async function newSdkClientEntity(options: any): Promise<SdkClientEntity>
       }
 
       case 'identifyEvent':
-        client.identify(params.identifyEvent!.context || params.identifyEvent!.user!);
+        client.identify(
+          (params.identifyEvent!.context as LDContext) || params.identifyEvent!.user!,
+        );
         return undefined;
 
       case 'customEvent': {
@@ -439,8 +325,8 @@ export async function newSdkClientEntity(options: any): Promise<SdkClientEntity>
         const migrationVariation = params.migrationVariation!;
         const res = await client.migrationVariation(
           migrationVariation.key,
-          migrationVariation.context,
-          migrationVariation.defaultStage,
+          migrationVariation.context as LDContext,
+          migrationVariation.defaultStage as LDMigrationStage,
         );
         return { result: res.value };
       }
@@ -504,8 +390,8 @@ export async function newSdkClientEntity(options: any): Promise<SdkClientEntity>
           case 'read': {
             const res = await migration.read(
               migrationOperation.key,
-              migrationOperation.context,
-              migrationOperation.defaultStage,
+              migrationOperation.context as LDContext,
+              migrationOperation.defaultStage as LDMigrationStage,
               migrationOperation.payload,
             );
             if (res.success) {
@@ -516,8 +402,8 @@ export async function newSdkClientEntity(options: any): Promise<SdkClientEntity>
           case 'write': {
             const res = await migration.write(
               migrationOperation.key,
-              migrationOperation.context,
-              migrationOperation.defaultStage,
+              migrationOperation.context as LDContext,
+              migrationOperation.defaultStage as LDMigrationStage,
               migrationOperation.payload,
             );
 
diff --git a/packages/sdk/shopify-oxygen/contract-tests/package.json b/packages/sdk/shopify-oxygen/contract-tests/package.json
index 30d72f702e..f2124f2020 100644
--- a/packages/sdk/shopify-oxygen/contract-tests/package.json
+++ b/packages/sdk/shopify-oxygen/contract-tests/package.json
@@ -11,6 +11,7 @@
   "license": "Apache-2.0",
   "private": true,
   "dependencies": {
+    "@launchdarkly/js-contract-test-utils": "workspace:^",
     "@launchdarkly/js-server-sdk-common": "workspace:^",
     "@launchdarkly/shopify-oxygen-sdk": "workspace:^",
     "express": "^5.0.1"
diff --git a/packages/sdk/shopify-oxygen/contract-tests/src/utils/clientPool.ts b/packages/sdk/shopify-oxygen/contract-tests/src/utils/clientPool.ts
index f509631aee..d0ca93dcdb 100644
--- a/packages/sdk/shopify-oxygen/contract-tests/src/utils/clientPool.ts
+++ b/packages/sdk/shopify-oxygen/contract-tests/src/utils/clientPool.ts
@@ -1,42 +1,23 @@
 import { Response } from 'express';
 
+import { ClientPool as GenericClientPool } from '@launchdarkly/js-contract-test-utils';
 import { LDClient } from '@launchdarkly/js-server-sdk-common';
 import { init } from '@launchdarkly/shopify-oxygen-sdk';
 
 /* eslint-disable no-console */
 
-// NOTE: Currently, this is a very simple client pool that only really handles the
-// very limited Oxygen specific use cases... we should be expand this to be more
-// general purpose in the future and maybe even come up with some shared ts interface
-// to facilitate future contract testing.
-
-// TODO: currently this class will handle the response sending as well, which may technically
-// sit outside the scope of what it SHOULD be doing. We should refactor this to be more
-// general purpose and allow the caller to handle the response sending.
-
 /**
- * ClientPool is a singleton that manages a pool of LDClient instances. Currently there is
- * no separation between a managed client and this pool. Which means all of the client specs
- * will be implemented in this class.
+ * ClientPool manages a pool of LDClient instances for contract tests.
+ * It uses the shared generic ClientPool for client storage and ID generation, and
+ * handles SDK-specific client creation, command execution, and response sending.
  *
  * @see https://github.com/launchdarkly/sdk-test-harness/blob/v2/docs/service_spec.md
  */
 export default class ClientPool {
-  private _clients: Record<string, LDClient> = {};
-  private _clientCounter = 0;
-
-  constructor() {
-    this._clients = {};
-    this._clientCounter = 0;
-  }
-
-  private _makeId(): string {
-    this._clientCounter += 1;
-    return `client-${this._clientCounter}`;
-  }
+  private _pool = new GenericClientPool<LDClient>();
 
   public async runCommand(id: string, body: any, res: Response): Promise<void> {
-    const client = this._clients[id];
+    const client = this._pool.get(id);
     // TODO: handle the 'itCanFailCase'
     if (client) {
       try {
@@ -69,10 +50,10 @@ export default class ClientPool {
   }
 
   public async deleteClient(id: string, res: Response): Promise<void> {
-    const client = this._clients[id];
+    const client = this._pool.get(id);
     if (client) {
       client.close();
-      delete this._clients[id];
+      this._pool.remove(id);
       res.status(204);
       res.send();
     } else {
@@ -83,7 +64,6 @@ export default class ClientPool {
 
   public async createClient(options: any, res: Response): Promise<void> {
     try {
-      const id = this._makeId();
       const {
         configuration: { credential = 'unknown-sdk-key', polling },
       } = options;
@@ -101,7 +81,7 @@ export default class ClientPool {
       });
 
       await client.waitForInitialization({ timeout: 10 });
-      this._clients[id] = client;
+      const id = this._pool.add(client);
       res.status(201);
       res.set('Location', `/clients/${id}`);
       if (!client.initialized()) {
diff --git a/packages/sdk/shopify-oxygen/contract-tests/tsup.config.ts b/packages/sdk/shopify-oxygen/contract-tests/tsup.config.ts
index 0758f21c40..300be1bd30 100644
--- a/packages/sdk/shopify-oxygen/contract-tests/tsup.config.ts
+++ b/packages/sdk/shopify-oxygen/contract-tests/tsup.config.ts
@@ -7,6 +7,7 @@ export default defineConfig({
   entry: {
     index: 'src/index.ts',
   },
+  noExternal: ['@launchdarkly/js-contract-test-utils'],
   minify: true,
   format: ['esm', 'cjs'],
   splitting: false,
diff --git a/packages/tooling/contract-test-utils/package.json b/packages/tooling/contract-test-utils/package.json
index de1dd22804..6f07b01152 100644
--- a/packages/tooling/contract-test-utils/package.json
+++ b/packages/tooling/contract-test-utils/package.json
@@ -3,36 +3,60 @@
   "version": "0.0.0",
   "private": true,
   "type": "module",
-  "main": "./src/index.ts",
-  "types": "./src/index.ts",
+  "main": "./dist/index.js",
+  "types": "./dist/index.d.ts",
   "exports": {
     ".": {
-      "types": "./src/index.ts",
-      "import": "./src/index.ts",
-      "default": "./src/index.ts"
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js",
+      "default": "./dist/index.js"
     },
     "./client": {
-      "types": "./src/client.ts",
-      "import": "./src/client.ts",
-      "default": "./src/client.ts"
+      "types": "./dist/client.d.ts",
+      "import": "./dist/client.js",
+      "default": "./dist/client.js"
+    },
+    "./server": {
+      "types": "./dist/server.d.ts",
+      "import": "./dist/server.js",
+      "default": "./dist/server.js"
     }
   },
   "typesVersions": {
     "*": {
       "client": [
-        "./src/client.ts"
+        "./dist/client.d.ts"
+      ],
+      "server": [
+        "./dist/server.d.ts"
       ]
     }
   },
   "scripts": {
-    "build": "tsc",
+    "build": "tsc && tsc -p tsconfig.client.json && tsc -p tsconfig.server.json",
+    "build:client": "tsc -p tsconfig.client.json",
+    "build:server": "tsc -p tsconfig.server.json",
     "clean": "rimraf dist"
   },
-  "dependencies": {
-    "@launchdarkly/js-client-sdk-common": "workspace:^"
+  "peerDependencies": {
+    "@launchdarkly/js-client-sdk-common": "workspace:^",
+    "@launchdarkly/js-server-sdk-common": "workspace:^",
+    "got": "14.4.7"
+  },
+  "peerDependenciesMeta": {
+    "@launchdarkly/js-client-sdk-common": {
+      "optional": true
+    },
+    "@launchdarkly/js-server-sdk-common": {
+      "optional": true
+    },
+    "got": {
+      "optional": true
+    }
   },
   "devDependencies": {
     "@types/node": "^18.11.9",
+    "got": "14.4.7",
     "typescript": "^4.9.0"
   }
 }
diff --git a/packages/tooling/contract-test-utils/src/client-side/TestHook.ts b/packages/tooling/contract-test-utils/src/client-side/TestHook.ts
index 9a107f420f..b9072ca6b0 100644
--- a/packages/tooling/contract-test-utils/src/client-side/TestHook.ts
+++ b/packages/tooling/contract-test-utils/src/client-side/TestHook.ts
@@ -6,32 +6,10 @@ import {
   LDEvaluationDetail,
   TrackSeriesContext,
 } from '@launchdarkly/js-client-sdk-common';
+import { BaseTestHook } from '../shared/BaseTestHook.js';
 
-export interface HookData {
-  beforeEvaluation?: Record<string, unknown>;
-  afterEvaluation?: Record<string, unknown>;
-}
-
-export interface HookErrors {
-  beforeEvaluation?: string;
-  afterEvaluation?: string;
-  afterTrack?: string;
-}
-
-export default class TestHook implements Hook {
-  private _name: string;
-  private _endpoint: string;
-  private _data?: HookData;
-  private _errors?: HookErrors;
-
-  constructor(name: string, endpoint: string, data?: HookData, errors?: HookErrors) {
-    this._name = name;
-    this._endpoint = endpoint;
-    this._data = data;
-    this._errors = errors;
-  }
-
-  private async _safePost(body: unknown): Promise<void> {
+export default class TestHook extends BaseTestHook implements Hook {
+  protected async _safePost(body: unknown): Promise<void> {
     try {
       await fetch(this._endpoint, {
         method: 'POST',
@@ -43,25 +21,18 @@ export default class TestHook implements Hook {
     }
   }
 
-  getMetadata(): HookMetadata {
-    return {
-      name: this._name,
-    };
+  override getMetadata(): HookMetadata {
+    return super.getMetadata();
   }
 
   beforeEvaluation(
     hookContext: EvaluationSeriesContext,
     data: EvaluationSeriesData,
   ): EvaluationSeriesData {
-    if (this._errors?.beforeEvaluation) {
-      throw new Error(this._errors.beforeEvaluation);
-    }
-    this._safePost({
-      evaluationSeriesContext: hookContext,
-      evaluationSeriesData: data,
-      stage: 'beforeEvaluation',
-    });
-    return { ...data, ...(this._data?.beforeEvaluation || {}) };
+    return this._beforeEvaluationImpl(
+      hookContext as unknown as Record<string, unknown>,
+      data,
+    ) as EvaluationSeriesData;
   }
 
   afterEvaluation(
@@ -69,17 +40,11 @@ export default class TestHook implements Hook {
     data: EvaluationSeriesData,
     detail: LDEvaluationDetail,
   ): EvaluationSeriesData {
-    if (this._errors?.afterEvaluation) {
-      throw new Error(this._errors.afterEvaluation);
-    }
-    this._safePost({
-      evaluationSeriesContext: hookContext,
-      evaluationSeriesData: data,
-      stage: 'afterEvaluation',
-      evaluationDetail: detail,
-    });
-
-    return { ...data, ...(this._data?.afterEvaluation || {}) };
+    return this._afterEvaluationImpl(
+      hookContext as unknown as Record<string, unknown>,
+      data,
+      detail,
+    ) as EvaluationSeriesData;
   }
 
   afterTrack(hookContext: TrackSeriesContext): void {
diff --git a/packages/tooling/contract-test-utils/src/client.ts b/packages/tooling/contract-test-utils/src/client.ts
index d0a167b519..80469be6b1 100644
--- a/packages/tooling/contract-test-utils/src/client.ts
+++ b/packages/tooling/contract-test-utils/src/client.ts
@@ -1,9 +1,5 @@
 // Re-export universal exports
-export * from './index';
+export * from './index.js';
 
 // Client-side exports
-export { default as ClientSideTestHook } from './client-side/TestHook';
-export type {
-  HookData as ClientSideHookData,
-  HookErrors as ClientSideHookErrors,
-} from './client-side/TestHook';
+export { default as ClientSideTestHook } from './client-side/TestHook.js';
diff --git a/packages/tooling/contract-test-utils/src/index.ts b/packages/tooling/contract-test-utils/src/index.ts
index 82c54b0dcb..f227ed20f3 100644
--- a/packages/tooling/contract-test-utils/src/index.ts
+++ b/packages/tooling/contract-test-utils/src/index.ts
@@ -1,20 +1,5 @@
-// Universal exports (no SDK dependency)
-export * from './types/CommandParams';
-export {
-  type CreateInstanceParams,
-  type SDKConfigParams,
-  type SDKConfigTLSParams,
-  type SDKConfigServiceEndpointsParams,
-  type SDKConfigStreamingParams,
-  type SDKConfigPollingParams,
-  type SDKConfigEventParams,
-  type SDKConfigTagsParams,
-  type SDKConfigClientSideParams,
-  type SDKConfigEvaluationHookData,
-  type SDKConfigHookInstance,
-  type SDKConfigHooksParams,
-  type SDKConfigProxyParams,
-  type SDKConfigWrapper,
-} from './types/ConfigParams';
-export { makeLogger } from './logging/makeLogger';
-export { ClientPool } from './server-side/ClientPool';
+// Universal exports (types use minimal compat types, no SDK dependency)
+export * from './types/CommandParams.js';
+export * from './types/ConfigParams.js';
+export { makeLogger } from './logging/makeLogger.js';
+export { ClientPool } from './server-side/ClientPool.js';
diff --git a/packages/tooling/contract-test-utils/src/logging/makeLogger.ts b/packages/tooling/contract-test-utils/src/logging/makeLogger.ts
index ad01caf65d..65954ad83f 100644
--- a/packages/tooling/contract-test-utils/src/logging/makeLogger.ts
+++ b/packages/tooling/contract-test-utils/src/logging/makeLogger.ts
@@ -1,4 +1,4 @@
-import { LDLogger } from '@launchdarkly/js-client-sdk-common';
+import { LDLogger } from '../types/compat.js';
 
 export function makeLogger(tag: string): LDLogger {
   return {
diff --git a/packages/tooling/contract-test-utils/src/server-side/TestHook.ts b/packages/tooling/contract-test-utils/src/server-side/TestHook.ts
new file mode 100644
index 0000000000..37348117a3
--- /dev/null
+++ b/packages/tooling/contract-test-utils/src/server-side/TestHook.ts
@@ -0,0 +1,40 @@
+import got from 'got';
+import { integrations, LDEvaluationDetail } from '@launchdarkly/js-server-sdk-common';
+import { BaseTestHook } from '../shared/BaseTestHook.js';
+
+export default class TestHook extends BaseTestHook implements integrations.Hook {
+  protected async _safePost(body: unknown): Promise<void> {
+    try {
+      await got.post(this._endpoint, { json: body });
+    } catch {
+      // The test could move on before the post, so we are ignoring
+      // failed posts.
+    }
+  }
+
+  override getMetadata(): integrations.HookMetadata {
+    return super.getMetadata();
+  }
+
+  beforeEvaluation(
+    hookContext: integrations.EvaluationSeriesContext,
+    data: integrations.EvaluationSeriesData,
+  ): integrations.EvaluationSeriesData {
+    return this._beforeEvaluationImpl(
+      hookContext as unknown as Record<string, unknown>,
+      data,
+    ) as integrations.EvaluationSeriesData;
+  }
+
+  afterEvaluation(
+    hookContext: integrations.EvaluationSeriesContext,
+    data: integrations.EvaluationSeriesData,
+    detail: LDEvaluationDetail,
+  ): integrations.EvaluationSeriesData {
+    return this._afterEvaluationImpl(
+      hookContext as unknown as Record<string, unknown>,
+      data,
+      detail,
+    ) as integrations.EvaluationSeriesData;
+  }
+}
diff --git a/packages/tooling/contract-test-utils/src/server.ts b/packages/tooling/contract-test-utils/src/server.ts
new file mode 100644
index 0000000000..4c18533942
--- /dev/null
+++ b/packages/tooling/contract-test-utils/src/server.ts
@@ -0,0 +1,6 @@
+// Re-export universal exports
+export * from './index.js';
+
+// Server-side exports
+export { default as ServerSideTestHook } from './server-side/TestHook.js';
+export type { ServerSDKConfigParams } from './types/ConfigParams.js';
diff --git a/packages/tooling/contract-test-utils/src/shared/BaseTestHook.ts b/packages/tooling/contract-test-utils/src/shared/BaseTestHook.ts
new file mode 100644
index 0000000000..8df84059eb
--- /dev/null
+++ b/packages/tooling/contract-test-utils/src/shared/BaseTestHook.ts
@@ -0,0 +1,53 @@
+import { HookData, HookErrors } from '../types/CommandParams.js';
+
+export abstract class BaseTestHook {
+  protected readonly _name: string;
+  protected readonly _endpoint: string;
+  protected readonly _data?: HookData;
+  protected readonly _errors?: HookErrors;
+
+  constructor(name: string, endpoint: string, data?: HookData, errors?: HookErrors) {
+    this._name = name;
+    this._endpoint = endpoint;
+    this._data = data;
+    this._errors = errors;
+  }
+
+  protected abstract _safePost(body: unknown): Promise<void>;
+
+  getMetadata() {
+    return { name: this._name };
+  }
+
+  protected _beforeEvaluationImpl(
+    hookContext: Record<string, unknown>,
+    data: Record<string, unknown>,
+  ): Record<string, unknown> {
+    if (this._errors?.beforeEvaluation) {
+      throw new Error(this._errors.beforeEvaluation);
+    }
+    this._safePost({
+      evaluationSeriesContext: hookContext,
+      evaluationSeriesData: data,
+      stage: 'beforeEvaluation',
+    });
+    return { ...data, ...(this._data?.beforeEvaluation ?? {}) };
+  }
+
+  protected _afterEvaluationImpl(
+    hookContext: Record<string, unknown>,
+    data: Record<string, unknown>,
+    detail: unknown,
+  ): Record<string, unknown> {
+    if (this._errors?.afterEvaluation) {
+      throw new Error(this._errors.afterEvaluation);
+    }
+    this._safePost({
+      evaluationSeriesContext: hookContext,
+      evaluationSeriesData: data,
+      stage: 'afterEvaluation',
+      evaluationDetail: detail,
+    });
+    return { ...data, ...(this._data?.afterEvaluation ?? {}) };
+  }
+}
diff --git a/packages/tooling/contract-test-utils/src/types/CommandParams.ts b/packages/tooling/contract-test-utils/src/types/CommandParams.ts
index 2f67b8a10f..dccf9f3928 100644
--- a/packages/tooling/contract-test-utils/src/types/CommandParams.ts
+++ b/packages/tooling/contract-test-utils/src/types/CommandParams.ts
@@ -1,4 +1,4 @@
-import { LDContext, LDEvaluationReason } from '@launchdarkly/js-client-sdk-common';
+import { LDContext, LDEvaluationReason } from './compat.js';
 
 export const CommandType = {
   EvaluateFlag: 'evaluate',
@@ -11,6 +11,12 @@ export const CommandType = {
   ContextConvert: 'contextConvert',
   ContextComparison: 'contextComparison',
   SecureModeHash: 'secureModeHash',
+  // Server-specific commands
+  GetBigSegmentStoreStatus: 'getBigSegmentStoreStatus',
+  MigrationVariation: 'migrationVariation',
+  MigrationOperation: 'migrationOperation',
+  RegisterFlagChangeListener: 'registerFlagChangeListener',
+  UnregisterListener: 'unregisterListener',
 } as const;
 // eslint-disable-next-line @typescript-eslint/no-redeclare
 export type CommandType = (typeof CommandType)[keyof typeof CommandType];
@@ -35,6 +41,11 @@ export interface CommandParams {
   contextConvert?: ContextConvertParams;
   contextComparison?: ContextComparisonPairParams;
   secureModeHash?: SecureModeHashParams;
+  // Server-specific command fields
+  migrationVariation?: MigrationVariationParams;
+  migrationOperation?: MigrationOperationParams;
+  registerFlagChangeListener?: RegisterFlagChangeListenerParams;
+  unregisterListener?: UnregisterListenerParams;
 }
 
 export interface EvaluateFlagParams {
@@ -161,3 +172,45 @@ export interface HookExecutionPayload {
   evaluationDetail?: EvaluateFlagResponse;
   stage?: HookStage;
 }
+
+export interface HookData {
+  beforeEvaluation?: Record<string, unknown>;
+  afterEvaluation?: Record<string, unknown>;
+}
+
+export interface HookErrors {
+  beforeEvaluation?: string;
+  afterEvaluation?: string;
+  afterTrack?: string; // client-only; server ignores this field
+}
+
+// Server-specific command parameter types
+
+export interface MigrationVariationParams {
+  key: string;
+  context: LDContext;
+  defaultStage: string;
+}
+
+export interface MigrationOperationParams {
+  operation: string;
+  key: string;
+  context: LDContext;
+  defaultStage: string;
+  payload: any;
+  readExecutionOrder: string;
+  trackLatency?: boolean;
+  trackErrors?: boolean;
+  trackConsistency?: boolean;
+  newEndpoint: string;
+  oldEndpoint: string;
+}
+
+export interface RegisterFlagChangeListenerParams {
+  listenerId: string;
+  callbackUri: string;
+}
+
+export interface UnregisterListenerParams {
+  listenerId: string;
+}
diff --git a/packages/tooling/contract-test-utils/src/types/ConfigParams.ts b/packages/tooling/contract-test-utils/src/types/ConfigParams.ts
index 6727ff5e0b..971aa67bf0 100644
--- a/packages/tooling/contract-test-utils/src/types/ConfigParams.ts
+++ b/packages/tooling/contract-test-utils/src/types/ConfigParams.ts
@@ -1,6 +1,5 @@
-import { LDContext } from '@launchdarkly/js-client-sdk-common';
-
-import { HookStage } from './CommandParams';
+import { HookStage } from './CommandParams.js';
+import { LDContext } from './compat.js';
 
 export interface CreateInstanceParams {
   configuration: SDKConfigParams;
@@ -23,6 +22,11 @@ export interface SDKConfigParams {
   proxy?: SDKConfigProxyParams;
 }
 
+export interface ServerSDKConfigParams extends SDKConfigParams {
+  bigSegments?: SDKConfigBigSegmentsParams;
+  dataSystem?: SDKDataSystemParams;
+}
+
 export interface SDKConfigTLSParams {
   skipVerifyPeer?: boolean;
   customCAFile?: string;
@@ -93,3 +97,38 @@ export interface SDKConfigWrapper {
   name: string;
   version: string;
 }
+
+// Server-specific config types
+
+export interface SDKConfigBigSegmentsParams {
+  callbackUri: string;
+  userCacheSize?: number;
+  userCacheTimeMs?: number;
+  statusPollIntervalMs?: number;
+  staleAfterMs?: number;
+}
+
+export interface SDKDataSourceStreamingParams {
+  baseUri?: string;
+  initialRetryDelayMs?: number;
+}
+
+export interface SDKDataSourcePollingParams {
+  baseUri?: string;
+  pollIntervalMs?: number;
+}
+
+export interface SDKDataSystemSynchronizerParams {
+  streaming?: SDKDataSourceStreamingParams;
+  polling?: SDKDataSourcePollingParams;
+}
+
+export interface SDKDataSystemInitializerParams {
+  polling?: SDKDataSourcePollingParams;
+}
+
+export interface SDKDataSystemParams {
+  initializers?: SDKDataSystemInitializerParams[];
+  synchronizers?: SDKDataSystemSynchronizerParams[];
+  payloadFilter?: string;
+}
diff --git a/packages/tooling/contract-test-utils/src/types/compat.ts b/packages/tooling/contract-test-utils/src/types/compat.ts
new file mode 100644
index 0000000000..c673f35786
--- /dev/null
+++ b/packages/tooling/contract-test-utils/src/types/compat.ts
@@ -0,0 +1,32 @@
+/**
+ * Minimal type definitions for contract test utilities.
+ *
+ * These are compatible with the corresponding types from both
+ * @launchdarkly/js-client-sdk-common and @launchdarkly/js-server-sdk-common,
+ * allowing the shared package to work without depending on either SDK directly.
+ */
+
+/**
+ * A minimal LDContext type compatible with both client and server SDKs.
+ * Contract test harness passes context objects through without deep inspection.
+ */
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export type LDContext = Record<string, any>;
+
+/**
+ * A minimal LDEvaluationReason type compatible with both client and server SDKs.
+ */
+export interface LDEvaluationReason {
+  kind: string;
+  [key: string]: unknown;
+}
+
+/**
+ * A minimal LDLogger type compatible with both client and server SDKs.
+ */
+export interface LDLogger {
+  error(...args: any[]): void;
+  warn(...args: any[]): void;
+  info(...args: any[]): void;
+  debug(...args: any[]): void;
+}
diff --git a/packages/tooling/contract-test-utils/tsconfig.client.json b/packages/tooling/contract-test-utils/tsconfig.client.json
new file mode 100644
index 0000000000..57aed148f3
--- /dev/null
+++ b/packages/tooling/contract-test-utils/tsconfig.client.json
@@ -0,0 +1,5 @@
+{
+  "extends": "./tsconfig.json",
+  "include": ["src/**/*"],
+  "exclude": ["dist", "node_modules", "src/server.ts", "src/server-side/TestHook.ts"]
+}
diff --git a/packages/tooling/contract-test-utils/tsconfig.json b/packages/tooling/contract-test-utils/tsconfig.json
index 166160dbfa..079ac2afc6 100644
--- a/packages/tooling/contract-test-utils/tsconfig.json
+++ b/packages/tooling/contract-test-utils/tsconfig.json
@@ -17,5 +17,5 @@
     "skipLibCheck": true
   },
   "include": ["src/**/*"],
-  "exclude": ["dist", "node_modules"]
+  "exclude": ["dist", "node_modules", "src/client.ts", "src/client-side/TestHook.ts", "src/server.ts", "src/server-side/TestHook.ts"]
 }
diff --git a/packages/tooling/contract-test-utils/tsconfig.server.json b/packages/tooling/contract-test-utils/tsconfig.server.json
new file mode 100644
index 0000000000..fb3066bda8
--- /dev/null
+++ b/packages/tooling/contract-test-utils/tsconfig.server.json
@@ -0,0 +1,13 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    // 'got' is a devDependency; this path alias is needed because TypeScript's
+    // 'node' moduleResolution does not follow exports maps for ESM-only packages.
+    "baseUrl": ".",
+    "paths": {
+      "got": ["../../../node_modules/got/dist/source"]
+    }
+  },
+  "include": ["src/**/*"],
+  "exclude": ["dist", "node_modules", "src/client.ts", "src/client-side/**"]
+}