diff --git a/packages/event-processor/__tests__/pendingEventsStore.spec.ts b/packages/event-processor/__tests__/pendingEventsStore.spec.ts
index 23a8b4871..780b5ae13 100644
--- a/packages/event-processor/__tests__/pendingEventsStore.spec.ts
+++ b/packages/event-processor/__tests__/pendingEventsStore.spec.ts
@@ -93,7 +93,7 @@ describe('LocalStorageStore', () => {
       { uuid: '3', timestamp: 3, value: 'third' },
     ])
 
-    const newMap = {}
+    const newMap: { [key: string]: TestEntry } = {}
     store.values().forEach(item => {
       newMap[item.uuid] = {
         ...item,
diff --git a/packages/logging/src/logger.ts b/packages/logging/src/logger.ts
index 269968372..5da90e493 100644
--- a/packages/logging/src/logger.ts
+++ b/packages/logging/src/logger.ts
@@ -18,7 +18,15 @@ import { isValidEnum, sprintf } from '@optimizely/js-sdk-utils'
 
 import { LogLevel, LoggerFacade, LogManager, LogHandler } from './models'
 
-const stringToLogLevel = {
+type StringToLogLevel = {
+  NOTSET: number,
+  DEBUG: number,
+  INFO: number,
+  WARNING: number,
+  ERROR: number,
+}
+
+const stringToLogLevel: StringToLogLevel = {
   NOTSET: 0,
   DEBUG: 1,
   INFO: 2,
@@ -36,11 +44,11 @@ function coerceLogLevel(level: any): LogLevel {
     level = 'WARNING'
   }
 
-  if (!stringToLogLevel[level]) {
+  if (!stringToLogLevel[level as keyof StringToLogLevel]) {
     return level
   }
 
-  return stringToLogLevel[level]
+  return stringToLogLevel[level as keyof StringToLogLevel]
 }
 
 type LogData = {
diff --git a/packages/optimizely-sdk/lib/optimizely/index.ts b/packages/optimizely-sdk/lib/optimizely/index.ts
index e477cd351..d71db9cbc 100644
--- a/packages/optimizely-sdk/lib/optimizely/index.ts
+++ b/packages/optimizely-sdk/lib/optimizely/index.ts
@@ -78,6 +78,11 @@ export interface OptimizelyOptions {
   userProfileService?: UserProfileService | null;
 }
 
+// TODO: Make feature_key, user_id, variable_key, experiment_key, event_key camelCase
+export type InputKey = 'feature_key' | 'user_id' | 'variable_key' | 'experiment_key' | 'event_key' | 'variation_id';
+
+export type StringInputs = Partial<Record<InputKey, unknown>>;
+
 /**
  * The Optimizely class
  * @param {OptimizelyOptions} config
@@ -581,15 +586,14 @@ export default class Optimizely {
 
   /**
    * Validate string inputs, user attributes and event tags.
-   * @param  {unknown}  stringInputs   Map of string keys and associated values
-   * @param  {unknown}  userAttributes Optional parameter for user's attributes
-   * @param  {unknown}  eventTags      Optional parameter for event tags
-   * @return {boolean}                 True if inputs are valid
+   * @param  {StringInputs}  stringInputs   Map of string keys and associated values
+   * @param  {unknown}       userAttributes Optional parameter for user's attributes
+   * @param  {unknown}       eventTags      Optional parameter for event tags
+   * @return {boolean}                      True if inputs are valid
    *
    */
   private validateInputs(
-    // TODO: Make feature_key, user_id, variable_key, experiment_key camelCase
-    stringInputs: Partial<Record<'feature_key' | 'user_id' | 'variable_key' | 'experiment_key' | 'event_key', unknown>>,
+    stringInputs: StringInputs,
     userAttributes?: unknown,
     eventTags?: unknown
   ): boolean {
@@ -603,7 +607,7 @@ export default class Optimizely {
         delete stringInputs['user_id'];
       }
       Object.keys(stringInputs).forEach(key => {
-        if (!stringValidator.validate(stringInputs[key])) {
+        if (!stringValidator.validate(stringInputs[key as InputKey])) {
           throw new Error(sprintf(ERROR_MESSAGES.INVALID_INPUT_FORMAT, MODULE_NAME, key));
         }
       })
@@ -1196,7 +1200,7 @@ export default class Optimizely {
 
       const decisionObj = this.decisionService.getVariationForFeature(configObj, featureFlag, userId, attributes);
       const featureEnabled = decision.getFeatureEnabledFromVariation(decisionObj);
-      const allVariables = {};
+      const allVariables: { [variableKey: string]: unknown } = {};
 
       featureFlag.variables.forEach((variable: FeatureVariable) => {
         allVariables[variable.key] = this.getFeatureVariableValueFromVariation(featureKey, featureEnabled, decisionObj.variation, variable, userId);
diff --git a/packages/optimizely-sdk/lib/shared_types.ts b/packages/optimizely-sdk/lib/shared_types.ts
index 3ec5e3ee4..31423ba34 100644
--- a/packages/optimizely-sdk/lib/shared_types.ts
+++ b/packages/optimizely-sdk/lib/shared_types.ts
@@ -11,7 +11,7 @@ export interface UserProfile {
   user_id: string;
   experiment_bucket_map: {
     [experiment_id: string]: {
-        variation_id: string;
+      variation_id: string;
     };
   };
 }
@@ -71,7 +71,7 @@ export interface Variation {
 export interface Experiment {
   id: string;
   key: string;
-  variationKeyMap: {[key: string]: Variation}
+  variationKeyMap: { [key: string]: Variation }
 }
 
 export interface FeatureVariable {
@@ -87,7 +87,7 @@ export interface FeatureFlag {
   id: string;
   experimentIds: string[],
   variables: FeatureVariable[],
-  variableKeyMap: {[key: string]: FeatureVariable}
+  variableKeyMap: { [key: string]: FeatureVariable }
 }
 
 export interface FeatureKeyMap {
@@ -99,6 +99,10 @@ export interface OnReadyResult {
   reason?: string;
 }
 
+export type ObjectWithUnknownProperties = {
+  [key: string]: unknown;
+}
+
 /**
  * Optimizely Config Entities
  */
diff --git a/packages/optimizely-sdk/lib/utils/attributes_validator/index.ts b/packages/optimizely-sdk/lib/utils/attributes_validator/index.ts
index 8fdccbe50..e3c475390 100644
--- a/packages/optimizely-sdk/lib/utils/attributes_validator/index.ts
+++ b/packages/optimizely-sdk/lib/utils/attributes_validator/index.ts
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 import { sprintf } from '@optimizely/js-sdk-utils';
+import { ObjectWithUnknownProperties } from '../../shared_types';
 
 import fns from '../../utils/fns';
 import { ERROR_MESSAGES } from '../enums';
@@ -30,7 +31,7 @@ const MODULE_NAME = 'ATTRIBUTES_VALIDATOR';
 export function validate(attributes: unknown): boolean {
   if (typeof attributes === 'object' && !Array.isArray(attributes) && attributes !== null) {
     Object.keys(attributes).forEach(function(key) {
-      if (typeof attributes[key] === 'undefined') {
+      if (typeof (attributes as ObjectWithUnknownProperties)[key] === 'undefined') {
         throw new Error(sprintf(ERROR_MESSAGES.UNDEFINED_ATTRIBUTE, MODULE_NAME, key));
       }
     });
diff --git a/packages/optimizely-sdk/lib/utils/config_validator/index.ts b/packages/optimizely-sdk/lib/utils/config_validator/index.ts
index d71841581..ef156555a 100644
--- a/packages/optimizely-sdk/lib/utils/config_validator/index.ts
+++ b/packages/optimizely-sdk/lib/utils/config_validator/index.ts
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 import { sprintf } from '@optimizely/js-sdk-utils';
+import { ObjectWithUnknownProperties } from '../../shared_types';
 
 import { 
   ERROR_MESSAGES, 
@@ -34,13 +35,17 @@ const SUPPORTED_VERSIONS = [DATAFILE_VERSIONS.V2, DATAFILE_VERSIONS.V3, DATAFILE
  */
 export const validate = function(config: unknown): boolean {
   if (typeof config === 'object' && config !== null) {
-    if (config['errorHandler'] && typeof config['errorHandler'].handleError !== 'function') {
+    const configObj = config as ObjectWithUnknownProperties;
+    const errorHandler = configObj['errorHandler'];
+    const eventDispatcher = configObj['eventDispatcher'];
+    const logger = configObj['logger'];
+    if (errorHandler && typeof (errorHandler as ObjectWithUnknownProperties)['handleError'] !== 'function') {
       throw new Error(sprintf(ERROR_MESSAGES.INVALID_ERROR_HANDLER, MODULE_NAME));
     }
-    if (config['eventDispatcher'] && typeof config['eventDispatcher'].dispatchEvent !== 'function') {
+    if (eventDispatcher && typeof (eventDispatcher as ObjectWithUnknownProperties)['dispatchEvent'] !== 'function') {
       throw new Error(sprintf(ERROR_MESSAGES.INVALID_EVENT_DISPATCHER, MODULE_NAME));
     }
-    if (config['logger'] && typeof config['logger'].log !== 'function') {
+    if (logger && typeof (logger as ObjectWithUnknownProperties)['log'] !== 'function') {
       throw new Error(sprintf(ERROR_MESSAGES.INVALID_LOGGER, MODULE_NAME));
     }
     return true;
@@ -71,8 +76,8 @@ export const validateDatafile = function(datafile: unknown): any {
     }
   }
   if (typeof datafile === 'object' && !Array.isArray(datafile) && datafile !== null) {
-    if (SUPPORTED_VERSIONS.indexOf(datafile['version']) === -1) {
-      throw new Error(sprintf(ERROR_MESSAGES.INVALID_DATAFILE_VERSION, MODULE_NAME, datafile['version']));
+    if (SUPPORTED_VERSIONS.indexOf(datafile['version' as keyof unknown]) === -1) {
+      throw new Error(sprintf(ERROR_MESSAGES.INVALID_DATAFILE_VERSION, MODULE_NAME, datafile['version' as keyof unknown]));
     }
   }
 
diff --git a/packages/optimizely-sdk/lib/utils/fns/index.ts b/packages/optimizely-sdk/lib/utils/fns/index.ts
index e2e5800f6..59be164a9 100644
--- a/packages/optimizely-sdk/lib/utils/fns/index.ts
+++ b/packages/optimizely-sdk/lib/utils/fns/index.ts
@@ -52,7 +52,8 @@ function isSafeInteger(number: unknown): boolean {
 function keyBy<K>(arr: K[], key: string): { [key: string]: K } {
   if (!arr) return {};
   return keyByUtil(arr, function (item) {
-    return item[key];
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    return (item as any)[key];
   });
 }
 
diff --git a/packages/optimizely-sdk/lib/utils/user_profile_service_validator/index.ts b/packages/optimizely-sdk/lib/utils/user_profile_service_validator/index.ts
index 9c264178e..ea59c8220 100644
--- a/packages/optimizely-sdk/lib/utils/user_profile_service_validator/index.ts
+++ b/packages/optimizely-sdk/lib/utils/user_profile_service_validator/index.ts
@@ -19,6 +19,7 @@
  */
 
 import { sprintf } from '@optimizely/js-sdk-utils';
+import { ObjectWithUnknownProperties } from '../../shared_types';
 
 import { ERROR_MESSAGES } from '../enums';
 
@@ -33,9 +34,9 @@ const MODULE_NAME = 'USER_PROFILE_SERVICE_VALIDATOR';
 
 export function validate(userProfileServiceInstance: unknown): boolean {
   if (typeof userProfileServiceInstance === 'object' && userProfileServiceInstance !== null) {
-    if (typeof userProfileServiceInstance['lookup'] !== 'function') {
+    if (typeof (userProfileServiceInstance as ObjectWithUnknownProperties)['lookup'] !== 'function') {
       throw new Error(sprintf(ERROR_MESSAGES.INVALID_USER_PROFILE_SERVICE, MODULE_NAME, "Missing function 'lookup'"));
-    } else if (typeof userProfileServiceInstance['save'] !== 'function') {
+    } else if (typeof (userProfileServiceInstance as ObjectWithUnknownProperties)['save'] !== 'function') {
       throw new Error(sprintf(ERROR_MESSAGES.INVALID_USER_PROFILE_SERVICE, MODULE_NAME, "Missing function 'save'"));
     }
     return true;
diff --git a/tsconfig.json b/tsconfig.json
index 000ff9c89..1073836e9 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -19,7 +19,6 @@
     // "composite": true,                     /* Enable project compilation */
     // "removeComments": true,                /* Do not emit comments to output. */
     // "noEmit": true,                        /* Do not emit outputs. */
-    "suppressImplicitAnyIndexErrors": true,
     // "importHelpers": true /* Import emit helpers from 'tslib'. */,
     // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
     // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */