diff --git a/tsconfig.base.json b/tsconfig.base.json
index 58a6237846a54..0aad8d6b9c124 100644
--- a/tsconfig.base.json
+++ b/tsconfig.base.json
@@ -39,6 +39,8 @@
     // Resolve modules in the same way as Node.js. Aka make `require` works the
     // same in TypeScript as it does in Node.js.
     "moduleResolution": "node",
+    // "resolveJsonModule" allows for importing, extracting types from and generating .json files.
+    "resolveJsonModule": true,
     // Disallow inconsistently-cased references to the same file.
     "forceConsistentCasingInFileNames": true,
     // Forbid unused local variables as the rule was deprecated by ts-lint
diff --git a/typings/index.d.ts b/typings/index.d.ts
index 6d97aca4024c3..db6530d3f9e0b 100644
--- a/typings/index.d.ts
+++ b/typings/index.d.ts
@@ -35,15 +35,6 @@ declare module '*.svg' {
   export default content;
 }
 
-// allow JSON files to be imported directly without lint errors
-// see: https://github.com/palantir/tslint/issues/1264#issuecomment-228433367
-// and: https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#arbitrary-expressions-are-forbidden-in-export-assignments-in-ambient-contexts
-declare module '*.json' {
-  const json: any;
-  // eslint-disable-next-line import/no-default-export
-  export default json;
-}
-
 type MethodKeysOf<T> = {
   [K in keyof T]: T[K] extends (...args: any[]) => any ? K : never;
 }[keyof T];
diff --git a/x-pack/plugins/apm/public/components/app/ErrorGroupOverview/List/__test__/List.test.tsx b/x-pack/plugins/apm/public/components/app/ErrorGroupOverview/List/__test__/List.test.tsx
index 84b72b62248b0..a5a38da3d5d88 100644
--- a/x-pack/plugins/apm/public/components/app/ErrorGroupOverview/List/__test__/List.test.tsx
+++ b/x-pack/plugins/apm/public/components/app/ErrorGroupOverview/List/__test__/List.test.tsx
@@ -43,6 +43,7 @@ describe('ErrorGroupOverview -> List', () => {
       <MemoryRouter>
         <MockApmPluginContextWrapper>
           <MockUrlParamsContextProvider>
+            {/* @ts-expect-error invalid json props */}
             <ErrorGroupList items={props.items} serviceName="opbeans-python" />
           </MockUrlParamsContextProvider>
         </MockApmPluginContextWrapper>
diff --git a/x-pack/plugins/apm/public/components/shared/Links/DiscoverLinks/__test__/DiscoverTransactionButton.test.tsx b/x-pack/plugins/apm/public/components/shared/Links/DiscoverLinks/__test__/DiscoverTransactionButton.test.tsx
index 02e0e72826f3a..17dca4796ec74 100644
--- a/x-pack/plugins/apm/public/components/shared/Links/DiscoverLinks/__test__/DiscoverTransactionButton.test.tsx
+++ b/x-pack/plugins/apm/public/components/shared/Links/DiscoverLinks/__test__/DiscoverTransactionButton.test.tsx
@@ -15,6 +15,7 @@ import mockTransaction from './mockTransaction.json';
 
 describe('DiscoverTransactionLink component', () => {
   it('should render with data', () => {
+    // @ts-expect-error invalid json mock
     const transaction: Transaction = mockTransaction;
 
     expect(
@@ -25,6 +26,7 @@ describe('DiscoverTransactionLink component', () => {
 
 describe('getDiscoverQuery', () => {
   it('should return the correct query params object', () => {
+    // @ts-expect-error invalid json mock
     const transaction: Transaction = mockTransaction;
     const result = getDiscoverQuery(transaction);
     expect(result).toMatchSnapshot();
diff --git a/x-pack/plugins/apm/server/lib/service_map/group_resource_nodes.test.ts b/x-pack/plugins/apm/server/lib/service_map/group_resource_nodes.test.ts
index 2a9a2daf1fe47..23ef3f92e21a2 100644
--- a/x-pack/plugins/apm/server/lib/service_map/group_resource_nodes.test.ts
+++ b/x-pack/plugins/apm/server/lib/service_map/group_resource_nodes.test.ts
@@ -10,6 +10,7 @@ import expectedGroupedData from './mock_responses/group_resource_nodes_grouped.j
 
 describe('groupResourceNodes', () => {
   it('should group external nodes', () => {
+    // @ts-expect-error invalid json mock
     const responseWithGroups = groupResourceNodes(preGroupedData);
     expect(responseWithGroups.elements).toHaveLength(
       expectedGroupedData.elements.length
@@ -17,7 +18,7 @@ describe('groupResourceNodes', () => {
     for (const element of responseWithGroups.elements) {
       const expectedElement = expectedGroupedData.elements.find(
         ({ data: { id } }: { data: { id: string } }) => id === element.data.id
-      );
+      )!;
       expect(element).toMatchObject(expectedElement);
     }
   });
diff --git a/x-pack/plugins/apm/server/lib/services/annotations/index.test.ts b/x-pack/plugins/apm/server/lib/services/annotations/index.test.ts
index e1a3ee1c9380d..9bd9c7b7a1040 100644
--- a/x-pack/plugins/apm/server/lib/services/annotations/index.test.ts
+++ b/x-pack/plugins/apm/server/lib/services/annotations/index.test.ts
@@ -31,6 +31,7 @@ describe('getServiceAnnotations', () => {
             searchAggregatedTransactions: false,
           }),
         {
+          // @ts-expect-error invalid json mock
           mockResponse: () => noVersions,
         }
       );
@@ -50,6 +51,7 @@ describe('getServiceAnnotations', () => {
             searchAggregatedTransactions: false,
           }),
         {
+          // @ts-expect-error invalid json mock
           mockResponse: () => oneVersion,
         }
       );
@@ -74,6 +76,7 @@ describe('getServiceAnnotations', () => {
             searchAggregatedTransactions: false,
           }),
         {
+          // @ts-expect-error invalid json mock
           mockResponse: () => responses.shift(),
         }
       );
diff --git a/x-pack/plugins/canvas/canvas_plugin_src/functions/server/demodata/index.ts b/x-pack/plugins/canvas/canvas_plugin_src/functions/server/demodata/index.ts
index e29f1f511685e..102e6cdc726d5 100644
--- a/x-pack/plugins/canvas/canvas_plugin_src/functions/server/demodata/index.ts
+++ b/x-pack/plugins/canvas/canvas_plugin_src/functions/server/demodata/index.ts
@@ -61,6 +61,7 @@ export function demodata(): ExpressionFunctionDefinition<
             { id: 'project', name: 'project', meta: { type: 'string' } },
             { id: 'percent_uptime', name: 'percent_uptime', meta: { type: 'number' } },
           ],
+          // @ts-expect-error invalid json mock
           rows: sortBy(demoRows, 'time'),
         };
       } else if (args.type === DemoRows.SHIRTS) {
diff --git a/x-pack/plugins/canvas/shareable_runtime/components/__tests__/app.test.tsx b/x-pack/plugins/canvas/shareable_runtime/components/__tests__/app.test.tsx
index 8786788e13fd3..f2bc07defb14b 100644
--- a/x-pack/plugins/canvas/shareable_runtime/components/__tests__/app.test.tsx
+++ b/x-pack/plugins/canvas/shareable_runtime/components/__tests__/app.test.tsx
@@ -4,10 +4,10 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-/*	
-  One test relies on react-dom at a version of 16.9... it can be enabled	
-  once renovate completes the upgrade.  Relevant code has been commented out	
-  in the meantime.	
+/*
+  One test relies on react-dom at a version of 16.9... it can be enabled
+  once renovate completes the upgrade.  Relevant code has been commented out
+  in the meantime.
 */
 
 import { mount, ReactWrapper } from 'enzyme';
diff --git a/x-pack/plugins/canvas/shareable_runtime/test/index.ts b/x-pack/plugins/canvas/shareable_runtime/test/index.ts
index e07d94a6e1054..288dd0dc3a5be 100644
--- a/x-pack/plugins/canvas/shareable_runtime/test/index.ts
+++ b/x-pack/plugins/canvas/shareable_runtime/test/index.ts
@@ -11,4 +11,11 @@ import test from './workpads/test.json';
 export * from './utils';
 
 export type WorkpadNames = keyof typeof sharedWorkpads;
-export const sharedWorkpads = { hello, austin, test };
+export const sharedWorkpads = {
+  // TODO: the automatic types for these JSON files are insufficient, and "austin" is so massive
+  // that Typescript refuses to type it. These should be converted to TypeScript and typed to fit
+  // the requirements. "austin" should also be reduced to the necessary data
+  hello: hello as any,
+  austin: austin as any,
+  test: test as any,
+};
diff --git a/x-pack/plugins/infra/public/utils/apollo_client.ts b/x-pack/plugins/infra/public/utils/apollo_client.ts
index 3c69ef4c98fac..41831a03cabbb 100644
--- a/x-pack/plugins/infra/public/utils/apollo_client.ts
+++ b/x-pack/plugins/infra/public/utils/apollo_client.ts
@@ -16,6 +16,7 @@ export const createApolloClient = (fetch: HttpHandler) => {
   const cache = new InMemoryCache({
     addTypename: false,
     fragmentMatcher: new IntrospectionFragmentMatcher({
+      // @ts-expect-error apollo-cache-inmemory types don't match actual introspection data
       introspectionQueryResultData,
     }),
   });
diff --git a/x-pack/plugins/ml/public/application/components/annotations/annotation_description_list/index.test.tsx b/x-pack/plugins/ml/public/application/components/annotations/annotation_description_list/index.test.tsx
index 2568a6f40d326..e7330ca1dbe5d 100644
--- a/x-pack/plugins/ml/public/application/components/annotations/annotation_description_list/index.test.tsx
+++ b/x-pack/plugins/ml/public/application/components/annotations/annotation_description_list/index.test.tsx
@@ -21,6 +21,7 @@ describe('AnnotationDescriptionList', () => {
   });
 
   test('Initialization with annotation.', () => {
+    // @ts-expect-error mock data is too loosely typed
     const wrapper = shallowWithIntl(<AnnotationDescriptionList annotation={mockAnnotations[0]} />);
     expect(wrapper).toMatchSnapshot();
   });
diff --git a/x-pack/plugins/ml/public/application/data_frame_analytics/pages/analytics_management/components/action_delete/delete_action_name.test.tsx b/x-pack/plugins/ml/public/application/data_frame_analytics/pages/analytics_management/components/action_delete/delete_action_name.test.tsx
index e033af6436130..63c4a0fe889f6 100644
--- a/x-pack/plugins/ml/public/application/data_frame_analytics/pages/analytics_management/components/action_delete/delete_action_name.test.tsx
+++ b/x-pack/plugins/ml/public/application/data_frame_analytics/pages/analytics_management/components/action_delete/delete_action_name.test.tsx
@@ -51,6 +51,7 @@ describe('DeleteAction', () => {
 
   it('should display a tooltip when isDisabled prop is true.', () => {
     const { container } = render(
+      // @ts-expect-error mock data is incorrectly typed
       <DeleteActionName isDisabled={true} item={mockAnalyticsListItem} />
     );
 
@@ -59,6 +60,7 @@ describe('DeleteAction', () => {
 
   it('should not display a tooltip when isDisabled prop is false.', () => {
     const { container } = render(
+      // @ts-expect-error mock data is incorrectly typed
       <DeleteActionName isDisabled={false} item={mockAnalyticsListItem} />
     );
 
@@ -78,8 +80,12 @@ describe('DeleteAction', () => {
             {deleteAction.isModalVisible && <DeleteActionModal {...deleteAction} />}
             <button
               data-test-subj="mlAnalyticsJobDeleteButton"
-              onClick={() => deleteAction.openModal(mockAnalyticsListItem)}
+              onClick={() => {
+                // @ts-expect-error mock data is incorrectly typed
+                deleteAction.openModal(mockAnalyticsListItem);
+              }}
             >
+              {/* @ts-expect-error mock data is incorrectly typed */}
               <DeleteActionName isDisabled={false} item={mockAnalyticsListItem} />
             </button>
           </>
diff --git a/x-pack/plugins/ml/public/application/timeseriesexplorer/components/timeseries_chart/timeseries_chart_annotations.test.ts b/x-pack/plugins/ml/public/application/timeseriesexplorer/components/timeseries_chart/timeseries_chart_annotations.test.ts
index 240e840363a1f..cf7e2890c1fd2 100644
--- a/x-pack/plugins/ml/public/application/timeseriesexplorer/components/timeseries_chart/timeseries_chart_annotations.test.ts
+++ b/x-pack/plugins/ml/public/application/timeseriesexplorer/components/timeseries_chart/timeseries_chart_annotations.test.ts
@@ -10,6 +10,7 @@ import { getAnnotationLevels } from './timeseries_chart_annotations';
 
 describe('Timeseries Chart Annotations: getAnnotationLevels()', () => {
   test('getAnnotationLevels()', () => {
+    // @ts-expect-error mock data is too loosely typed
     const levels = getAnnotationLevels(mockAnnotationsOverlap);
     expect(levels).toEqual({ A: 0, B: 1, C: 2, D: 2 });
   });
diff --git a/x-pack/plugins/ml/server/models/job_validation/validate_time_range.test.ts b/x-pack/plugins/ml/server/models/job_validation/validate_time_range.test.ts
index 12458af0521a9..674a19e1db488 100644
--- a/x-pack/plugins/ml/server/models/job_validation/validate_time_range.test.ts
+++ b/x-pack/plugins/ml/server/models/job_validation/validate_time_range.test.ts
@@ -144,6 +144,7 @@ describe('ML - validateTimeRange', () => {
 
   it('invalid time field', () => {
     const mockSearchResponseInvalid = cloneDeep(mockSearchResponse);
+    // @ts-expect-error creating intentionally invalid data
     mockSearchResponseInvalid.fieldCaps = undefined;
     const duration = { start: 0, end: 1 };
     return validateTimeRange(
diff --git a/x-pack/plugins/security_solution/public/common/lib/compose/helpers.test.ts b/x-pack/plugins/security_solution/public/common/lib/compose/helpers.test.ts
index c34027648c896..01f74a5678be6 100644
--- a/x-pack/plugins/security_solution/public/common/lib/compose/helpers.test.ts
+++ b/x-pack/plugins/security_solution/public/common/lib/compose/helpers.test.ts
@@ -26,6 +26,7 @@ describe('getLinks helper', () => {
     const mockCache = new InMemoryCache({
       dataIdFromObject: () => null,
       fragmentMatcher: new IntrospectionFragmentMatcher({
+        // @ts-expect-error apollo-cache-inmemory types don't match actual introspection data
         introspectionQueryResultData,
       }),
     });
diff --git a/x-pack/plugins/security_solution/public/common/lib/compose/kibana_compose.tsx b/x-pack/plugins/security_solution/public/common/lib/compose/kibana_compose.tsx
index 30d3311a40b61..055e2591f7805 100644
--- a/x-pack/plugins/security_solution/public/common/lib/compose/kibana_compose.tsx
+++ b/x-pack/plugins/security_solution/public/common/lib/compose/kibana_compose.tsx
@@ -17,6 +17,7 @@ export function composeLibs(core: CoreStart): AppFrontendLibs {
   const cache = new InMemoryCache({
     dataIdFromObject: () => null,
     fragmentMatcher: new IntrospectionFragmentMatcher({
+      // @ts-expect-error apollo-cache-inmemory types don't match actual introspection data
       introspectionQueryResultData,
     }),
   });
diff --git a/x-pack/plugins/security_solution/public/timelines/components/timeline/body/renderers/suricata/suricata_links.ts b/x-pack/plugins/security_solution/public/timelines/components/timeline/body/renderers/suricata/suricata_links.ts
index fe6b44af202a8..4f389382dc475 100644
--- a/x-pack/plugins/security_solution/public/timelines/components/timeline/body/renderers/suricata/suricata_links.ts
+++ b/x-pack/plugins/security_solution/public/timelines/components/timeline/body/renderers/suricata/suricata_links.ts
@@ -7,8 +7,11 @@
 import { uniq } from 'lodash/fp';
 import { db } from 'suricata-sid-db';
 
+const has = <T>(obj: T, key: string | number | symbol): key is keyof T =>
+  Object.prototype.hasOwnProperty.call(obj, key);
+
 export const getLinksFromSignature = (id: number): string[] => {
-  const refs = db[id];
+  const refs = has(db, id) ? db[id] : null;
   if (refs != null) {
     return uniq(refs);
   } else {
diff --git a/x-pack/plugins/security_solution/server/lib/detection_engine/routes/index/get_signals_template.ts b/x-pack/plugins/security_solution/server/lib/detection_engine/routes/index/get_signals_template.ts
index cc22f34560c71..5ccde6d3eab97 100644
--- a/x-pack/plugins/security_solution/server/lib/detection_engine/routes/index/get_signals_template.ts
+++ b/x-pack/plugins/security_solution/server/lib/detection_engine/routes/index/get_signals_template.ts
@@ -8,7 +8,6 @@ import signalsMapping from './signals_mapping.json';
 import ecsMapping from './ecs_mapping.json';
 
 export const getSignalsTemplate = (index: string) => {
-  ecsMapping.mappings.properties.signal = signalsMapping.mappings.properties.signal;
   const template = {
     settings: {
       index: {
@@ -24,7 +23,13 @@ export const getSignalsTemplate = (index: string) => {
       },
     },
     index_patterns: [`${index}-*`],
-    mappings: ecsMapping.mappings,
+    mappings: {
+      ...ecsMapping.mappings,
+      properties: {
+        ...ecsMapping.mappings.properties,
+        signal: signalsMapping.mappings.properties.signal,
+      },
+    },
     version: 1,
   };
   return template;
diff --git a/x-pack/plugins/security_solution/server/lib/detection_engine/rules/get_prepackaged_rules.test.ts b/x-pack/plugins/security_solution/server/lib/detection_engine/rules/get_prepackaged_rules.test.ts
index ed1a239facf79..cf9a566cf4f90 100644
--- a/x-pack/plugins/security_solution/server/lib/detection_engine/rules/get_prepackaged_rules.test.ts
+++ b/x-pack/plugins/security_solution/server/lib/detection_engine/rules/get_prepackaged_rules.test.ts
@@ -33,12 +33,14 @@ describe('get_existing_prepackaged_rules', () => {
   });
 
   test('should throw an exception if a pre-packaged rule is not valid', () => {
+    // @ts-expect-error intentionally invalid argument
     expect(() => getPrepackagedRules([{ not_valid_made_up_key: true }])).toThrow(
       'name: "(rule name unknown)", rule_id: "(rule rule_id unknown)" within the folder rules/prepackaged_rules is not a valid detection engine rule. Expect the system to not work with pre-packaged rules until this rule is fixed or the file is removed. Error is: Invalid value "undefined" supplied to "description",Invalid value "undefined" supplied to "risk_score",Invalid value "undefined" supplied to "name",Invalid value "undefined" supplied to "severity",Invalid value "undefined" supplied to "type",Invalid value "undefined" supplied to "rule_id",Invalid value "undefined" supplied to "version", Full rule contents are:\n{\n  "not_valid_made_up_key": true\n}'
     );
   });
 
   test('should throw an exception with a message having rule_id and name in it', () => {
+    // @ts-expect-error intentionally invalid argument
     expect(() => getPrepackagedRules([{ name: 'rule name', rule_id: 'id-123' }])).toThrow(
       'name: "rule name", rule_id: "id-123" within the folder rules/prepackaged_rules is not a valid detection engine rule. Expect the system to not work with pre-packaged rules until this rule is fixed or the file is removed. Error is: Invalid value "undefined" supplied to "description",Invalid value "undefined" supplied to "risk_score",Invalid value "undefined" supplied to "severity",Invalid value "undefined" supplied to "type",Invalid value "undefined" supplied to "version", Full rule contents are:\n{\n  "name": "rule name",\n  "rule_id": "id-123"\n}'
     );
diff --git a/x-pack/plugins/security_solution/server/lib/detection_engine/rules/get_prepackaged_rules.ts b/x-pack/plugins/security_solution/server/lib/detection_engine/rules/get_prepackaged_rules.ts
index 354f8b90fae23..3d187d74432e8 100644
--- a/x-pack/plugins/security_solution/server/lib/detection_engine/rules/get_prepackaged_rules.ts
+++ b/x-pack/plugins/security_solution/server/lib/detection_engine/rules/get_prepackaged_rules.ts
@@ -15,6 +15,8 @@ import {
   AddPrepackagedRulesSchemaDecoded,
 } from '../../../../common/detection_engine/schemas/request/add_prepackaged_rules_schema';
 import { BadRequestError } from '../errors/bad_request_error';
+
+// TODO: convert rules files to TS and add explicit type definitions
 import { rawRules } from './prepackaged_rules';
 
 /**
@@ -49,5 +51,7 @@ export const validateAllPrepackagedRules = (
   });
 };
 
-export const getPrepackagedRules = (rules = rawRules): AddPrepackagedRulesSchemaDecoded[] =>
-  validateAllPrepackagedRules(rules);
+export const getPrepackagedRules = (
+  // @ts-expect-error mock data is too loosely typed
+  rules: AddPrepackagedRulesSchema[] = rawRules
+): AddPrepackagedRulesSchemaDecoded[] => validateAllPrepackagedRules(rules);
diff --git a/x-pack/plugins/transform/public/app/common/transform_stats.test.ts b/x-pack/plugins/transform/public/app/common/transform_stats.test.ts
index 342ca77a67b38..c030a24ff5c3c 100644
--- a/x-pack/plugins/transform/public/app/common/transform_stats.test.ts
+++ b/x-pack/plugins/transform/public/app/common/transform_stats.test.ts
@@ -12,11 +12,12 @@ import { getTransformProgress, isCompletedBatchTransform } from './transform_sta
 
 const getRow = (statsId: string) => {
   return {
+    // @ts-expect-error mock data does not actually match TransformListRow type
     ...(mockTransformListRow as TransformListRow),
     stats: {
-      ...mockTransformStats.transforms.find(
-        (stats: TransformListRow['stats']) => stats.id === statsId
-      ),
+      ...(mockTransformStats.transforms as Array<TransformListRow['stats']>).find(
+        (stats) => stats.id === statsId
+      )!,
     },
   };
 };
diff --git a/x-pack/plugins/transform/public/app/sections/transform_management/components/action_start/start_action_name.test.tsx b/x-pack/plugins/transform/public/app/sections/transform_management/components/action_start/start_action_name.test.tsx
index 9c06675d69ca4..87e890b1b9718 100644
--- a/x-pack/plugins/transform/public/app/sections/transform_management/components/action_start/start_action_name.test.tsx
+++ b/x-pack/plugins/transform/public/app/sections/transform_management/components/action_start/start_action_name.test.tsx
@@ -17,6 +17,7 @@ jest.mock('../../../../../app/app_dependencies');
 
 describe('Transform: Transform List Actions <StartAction />', () => {
   test('Minimal initialization', () => {
+    // @ts-expect-error mock data is too loosely typed
     const item: TransformListRow = transformListRow;
     const props: StartActionNameProps = {
       forceDisable: false,
diff --git a/x-pack/plugins/transform/public/app/sections/transform_management/components/action_stop/stop_action_name.test.tsx b/x-pack/plugins/transform/public/app/sections/transform_management/components/action_stop/stop_action_name.test.tsx
index 643e8c6126f0f..dcc26593de44b 100644
--- a/x-pack/plugins/transform/public/app/sections/transform_management/components/action_stop/stop_action_name.test.tsx
+++ b/x-pack/plugins/transform/public/app/sections/transform_management/components/action_stop/stop_action_name.test.tsx
@@ -17,6 +17,7 @@ jest.mock('../../../../../app/app_dependencies');
 
 describe('Transform: Transform List Actions <StopAction />', () => {
   test('Minimal initialization', () => {
+    // @ts-expect-error mock data is too loosely typed
     const item: TransformListRow = transformListRow;
     const props: StopActionNameProps = {
       forceDisable: false,
diff --git a/x-pack/plugins/transform/public/app/sections/transform_management/components/transform_list/common.test.ts b/x-pack/plugins/transform/public/app/sections/transform_management/components/transform_list/common.test.ts
index f6708f7c36f26..9a6988445c73d 100644
--- a/x-pack/plugins/transform/public/app/sections/transform_management/components/transform_list/common.test.ts
+++ b/x-pack/plugins/transform/public/app/sections/transform_management/components/transform_list/common.test.ts
@@ -15,14 +15,15 @@ describe('Transform: isCompletedBatchTransform()', () => {
     // check the transform config/state against the conditions
     // that will be used by isCompletedBatchTransform()
     // followed by a call to isCompletedBatchTransform() itself
+    // @ts-expect-error mock data is too loosely typed
     const row = mockTransformListRow as TransformListRow;
     expect(row.stats.checkpointing.last.checkpoint === 1).toBe(true);
     expect(row.config.sync === undefined).toBe(true);
     expect(row.stats.state === TRANSFORM_STATE.STOPPED).toBe(true);
-    expect(isCompletedBatchTransform(mockTransformListRow)).toBe(true);
+    expect(isCompletedBatchTransform(row)).toBe(true);
 
     // adapt the mock config to resemble a non-completed transform.
     row.stats.checkpointing.last.checkpoint = 0;
-    expect(isCompletedBatchTransform(mockTransformListRow)).toBe(false);
+    expect(isCompletedBatchTransform(row)).toBe(false);
   });
 });
diff --git a/x-pack/plugins/transform/public/app/sections/transform_management/components/transform_list/expanded_row.test.tsx b/x-pack/plugins/transform/public/app/sections/transform_management/components/transform_list/expanded_row.test.tsx
index 846d8a8ccd200..2a04668fe6017 100644
--- a/x-pack/plugins/transform/public/app/sections/transform_management/components/transform_list/expanded_row.test.tsx
+++ b/x-pack/plugins/transform/public/app/sections/transform_management/components/transform_list/expanded_row.test.tsx
@@ -27,6 +27,7 @@ describe('Transform: Transform List <ExpandedRow />', () => {
   });
 
   test('Minimal initialization', async () => {
+    // @ts-expect-error mock data is too loosely typed
     const item: TransformListRow = transformListRow;
 
     const { getByText, getByTestId } = render(<ExpandedRow item={item} />);
diff --git a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/checkup_tab.test.tsx b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/checkup_tab.test.tsx
index 9ba5441604ddc..a4054bacba448 100644
--- a/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/checkup_tab.test.tsx
+++ b/x-pack/plugins/upgrade_assistant/public/application/components/tabs/checkup/checkup_tab.test.tsx
@@ -25,6 +25,7 @@ const defaultProps = {
  */
 describe('CheckupTab', () => {
   test('render with deprecations', () => {
+    // @ts-expect-error mock data is too loosely typed
     expect(shallow(<CheckupTab {...defaultProps} />)).toMatchSnapshot();
   });
 
diff --git a/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.test.ts b/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.test.ts
index 4d6e3f51a83a0..e0518e9447ec5 100644
--- a/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.test.ts
+++ b/x-pack/plugins/upgrade_assistant/server/lib/es_migration_apis.test.ts
@@ -34,6 +34,7 @@ describe('getUpgradeAssistantStatus', () => {
   });
 
   beforeEach(() => {
+    // @ts-expect-error mock data is too loosely typed
     deprecationsResponse = _.cloneDeep(fakeDeprecations);
   });
 
diff --git a/x-pack/test/api_integration/services/infraops_graphql_client.ts b/x-pack/test/api_integration/services/infraops_graphql_client.ts
index 9eb2699431548..81f0ac8fad919 100644
--- a/x-pack/test/api_integration/services/infraops_graphql_client.ts
+++ b/x-pack/test/api_integration/services/infraops_graphql_client.ts
@@ -47,6 +47,7 @@ export function InfraOpsGraphQLClientFactoryProvider({ getService }: FtrProvider
     return new ApolloClient({
       cache: new InMemoryCache({
         fragmentMatcher: new IntrospectionFragmentMatcher({
+          // @ts-expect-error apollo-cache-inmemory types don't match actual introspection data
           introspectionQueryResultData,
         }),
       }),
diff --git a/x-pack/test/api_integration/services/security_solution_graphql_client.ts b/x-pack/test/api_integration/services/security_solution_graphql_client.ts
index 0bcf94fdb7d3f..c592ced623467 100644
--- a/x-pack/test/api_integration/services/security_solution_graphql_client.ts
+++ b/x-pack/test/api_integration/services/security_solution_graphql_client.ts
@@ -46,6 +46,7 @@ export function SecuritySolutionGraphQLClientFactoryProvider({ getService }: Ftr
     return new ApolloClient({
       cache: new InMemoryCache({
         fragmentMatcher: new IntrospectionFragmentMatcher({
+          // @ts-expect-error apollo-cache-inmemory types don't match actual introspection data
           introspectionQueryResultData,
         }),
       }),
diff --git a/x-pack/tsconfig.json b/x-pack/tsconfig.json
index d4722aba4882c..9a52aca381e87 100644
--- a/x-pack/tsconfig.json
+++ b/x-pack/tsconfig.json
@@ -15,7 +15,6 @@
     "plugins/licensing/**/*"
   ],
   "compilerOptions": {
-    "outDir": ".",
     "paths": {
       "kibana/public": ["src/core/public"],
       "kibana/server": ["src/core/server"],
diff --git a/x-pack/typings/index.d.ts b/x-pack/typings/index.d.ts
index 73efee0dab2eb..2c7ae2961101c 100644
--- a/x-pack/typings/index.d.ts
+++ b/x-pack/typings/index.d.ts
@@ -33,12 +33,3 @@ declare module 'axios/lib/adapters/xhr';
 type Writable<T> = {
   -readonly [K in keyof T]: T[K];
 };
-
-// allow JSON files to be imported directly without lint errors
-// see: https://github.com/palantir/tslint/issues/1264#issuecomment-228433367
-// and: https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#arbitrary-expressions-are-forbidden-in-export-assignments-in-ambient-contexts
-declare module '*.json' {
-  const json: any;
-  // eslint-disable-next-line import/no-default-export
-  export default json;
-}