diff --git a/.eslintrc.js b/.eslintrc.cjs
similarity index 73%
rename from .eslintrc.js
rename to .eslintrc.cjs
index fbb623ee1b..e42653fdf8 100644
--- a/.eslintrc.js
+++ b/.eslintrc.cjs
@@ -1,9 +1,10 @@
-'use strict'
-
 const { overrides } = require('@netlify/eslint-config-node')
 
 module.exports = {
   extends: ['plugin:fp/recommended', '@netlify/eslint-config-node'],
+  parserOptions: {
+    sourceType: 'module',
+  },
   rules: {
     strict: 2,
 
@@ -54,32 +55,17 @@ module.exports = {
         ],
       },
     ],
+    'import/extensions': [2, 'ignorePackages'],
   },
   overrides: [
     ...overrides,
-    {
-      files: ['**/tests.{cjs,mjs,js}', '**/tests/**/*.{cjs,mjs,js}'],
-      rules: {
-        'node/no-missing-import': 0,
-      },
-    },
     {
       files: ['**/fixtures/**/*.{cjs,mjs,js}'],
       rules: {
         'import/no-unresolved': 0,
+        'node/no-missing-import': 0,
       },
     },
-    {
-      files: ['**/fixtures/**/*edge-handlers*/**/*.js', '**/fixtures/*es_module*/**/*.js'],
-      parserOptions: {
-        sourceType: 'module',
-      },
-      rules: {
-        'node/no-unsupported-features/es-syntax': 0,
-        'ava/no-import-test-files': 0,
-      },
-    },
-
     // @todo As it stands, this rule is problematic with methods that get+send
     // many parameters, such as `runStep` in `src/steps/run_step.js`.
     // We should discuss whether we want to keep this rule or discontinue it.
@@ -123,30 +109,5 @@ module.exports = {
         'import/no-anonymous-default-export': 0,
       },
     },
-
-    {
-      files: ['packages/*/tests/**/*.{cjs,mjs,js}'],
-      rules: {
-        'no-magic-numbers': 'off',
-      },
-    },
-
-    // Those packages are using pure ES modules
-    {
-      files: [
-        'packages/build/**/*.{cjs,mjs,js}',
-        'packages/cache-utils/**/*.{cjs,mjs,js}',
-        'packages/config/**/*.{cjs,mjs,js}',
-        'packages/functions-utils/**/*.{cjs,mjs,js}',
-        'packages/git-utils/**/*.{cjs,mjs,js}',
-        'packages/run-utils/**/*.{cjs,mjs,js}',
-      ],
-      parserOptions: {
-        sourceType: 'module',
-      },
-      rules: {
-        'import/extensions': [2, 'ignorePackages'],
-      },
-    },
   ],
 }
diff --git a/commitlint.config.js b/commitlint.config.cjs
similarity index 82%
rename from commitlint.config.js
rename to commitlint.config.cjs
index 329a25f070..4fedde6daf 100644
--- a/commitlint.config.js
+++ b/commitlint.config.cjs
@@ -1,3 +1 @@
-'use strict'
-
 module.exports = { extends: ['@commitlint/config-conventional'] }
diff --git a/package.json b/package.json
index 537d403edf..5d2f900bed 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,7 @@
   "private": true,
   "version": "0.0.0",
   "description": "Netlify build module",
-  "main": "index.js",
+  "type": "module",
   "author": "Netlify Inc.",
   "scripts": {
     "test": "run-s format test:dev",
diff --git a/packages/build/tests/core/tests.mjs b/packages/build/tests/core/tests.mjs
index ccb9fadba3..928893e223 100644
--- a/packages/build/tests/core/tests.mjs
+++ b/packages/build/tests/core/tests.mjs
@@ -226,7 +226,8 @@ const getNodeBinary = async function (nodeVersion, retries = 1) {
 const MAX_RETRIES = 10
 
 // Memoize `get-node`
-const mGetNode = moize(getNodeBinary, { isPromise: true, maxSize: 1e3 })
+const GET_NODE_MOIZE_MAX_SIZE = 1e3
+const mGetNode = moize(getNodeBinary, { isPromise: true, maxSize: GET_NODE_MOIZE_MAX_SIZE })
 
 test('--node-path is used by build.command', async (t) => {
   const { path } = await mGetNode(CHILD_NODE_VERSION)
@@ -357,7 +358,7 @@ test.serial('Passes the right base path properties to zip-it-and-ship-it', async
   t.is(repositoryRoot, fixtureDir)
 })
 
-// eslint-disable-next-line max-statements
+/* eslint-disable max-statements, no-magic-numbers */
 test.serial('Passes the right feature flags to zip-it-and-ship-it', async (t) => {
   // eslint-disable-next-line import/no-named-as-default-member
   const mockZipFunctions = sinon.stub().resolves()
@@ -417,6 +418,7 @@ test.serial('Passes the right feature flags to zip-it-and-ship-it', async (t) =>
   t.true(mockZipFunctions.getCall(7).args[2].featureFlags.this_is_a_mock_flag)
   t.true(mockZipFunctions.getCall(7).args[2].featureFlags.and_another_one)
 })
+/* eslint-enable max-statements, no-magic-numbers */
 
 test('Print warning on lingering processes', async (t) => {
   const { returnValue } = await runFixture(t, 'lingering', {
diff --git a/packages/build/tests/edge_handlers/fixtures/simple/netlify/edge-handlers/test.js b/packages/build/tests/edge_handlers/fixtures/simple/netlify/edge-handlers/test.js
index 886501571b..73dea48bf0 100644
--- a/packages/build/tests/edge_handlers/fixtures/simple/netlify/edge-handlers/test.js
+++ b/packages/build/tests/edge_handlers/fixtures/simple/netlify/edge-handlers/test.js
@@ -1,5 +1,6 @@
 import isPlainObj from 'is-plain-obj'
 
+// eslint-disable-next-line ava/no-import-test-files
 import data from './data.json'
 
 export const onRequest = function (event) {
diff --git a/packages/build/tests/plugins/fixtures/commonjs_local/netlify.toml b/packages/build/tests/plugins/fixtures/commonjs_local/netlify.toml
index 81b0ce8bb1..384ddc321e 100644
--- a/packages/build/tests/plugins/fixtures/commonjs_local/netlify.toml
+++ b/packages/build/tests/plugins/fixtures/commonjs_local/netlify.toml
@@ -1,2 +1,2 @@
 [[plugins]]
-package = "./plugin"
+package = "./plugin.cjs"
diff --git a/packages/build/tests/plugins/fixtures/commonjs_local/plugin.js b/packages/build/tests/plugins/fixtures/commonjs_local/plugin.cjs
similarity index 100%
rename from packages/build/tests/plugins/fixtures/commonjs_local/plugin.js
rename to packages/build/tests/plugins/fixtures/commonjs_local/plugin.cjs
diff --git a/packages/build/tests/plugins/fixtures/ts_transpile_already/netlify.toml b/packages/build/tests/plugins/fixtures/ts_transpile_already/netlify.toml
index 81b0ce8bb1..384ddc321e 100644
--- a/packages/build/tests/plugins/fixtures/ts_transpile_already/netlify.toml
+++ b/packages/build/tests/plugins/fixtures/ts_transpile_already/netlify.toml
@@ -1,2 +1,2 @@
 [[plugins]]
-package = "./plugin"
+package = "./plugin.cjs"
diff --git a/packages/build/tests/plugins/fixtures/ts_transpile_already/plugin.js b/packages/build/tests/plugins/fixtures/ts_transpile_already/plugin.cjs
similarity index 100%
rename from packages/build/tests/plugins/fixtures/ts_transpile_already/plugin.js
rename to packages/build/tests/plugins/fixtures/ts_transpile_already/plugin.cjs
diff --git a/packages/build/tests/plugins/snapshots/tests.mjs.md b/packages/build/tests/plugins/snapshots/tests.mjs.md
index b19873f655..2c4d2352ab 100644
--- a/packages/build/tests/plugins/snapshots/tests.mjs.md
+++ b/packages/build/tests/plugins/snapshots/tests.mjs.md
@@ -252,21 +252,21 @@ Generated by [AVA](https://avajs.dev).
       plugins:␊
         - inputs: {}␊
           origin: config␊
-          package: ./plugin␊
+          package: ./plugin.cjs␊
     ␊
     > Context␊
       production␊
     ␊
     > Loading plugins␊
-       - ./plugin@1.0.0 from netlify.toml␊
+       - ./plugin.cjs@1.0.0 from netlify.toml␊
     ␊
     ────────────────────────────────────────────────────────────────␊
-      1. ./plugin (onPreBuild event)                                ␊
+      1. ./plugin.cjs (onPreBuild event)                            ␊
     ────────────────────────────────────────────────────────────────␊
     ␊
     true␊
     ␊
-    (./plugin onPreBuild completed in 1ms)␊
+    (./plugin.cjs onPreBuild completed in 1ms)␊
     ␊
     ────────────────────────────────────────────────────────────────␊
       Netlify Build Complete                                        ␊
@@ -2564,21 +2564,21 @@ Generated by [AVA](https://avajs.dev).
       plugins:␊
         - inputs: {}␊
           origin: config␊
-          package: ./plugin␊
+          package: ./plugin.cjs␊
     ␊
     > Context␊
       production␊
     ␊
     > Loading plugins␊
-       - ./plugin@1.0.0 from netlify.toml␊
+       - ./plugin.cjs@1.0.0 from netlify.toml␊
     ␊
     ────────────────────────────────────────────────────────────────␊
-      1. ./plugin (onPreBuild event)                                ␊
+      1. ./plugin.cjs (onPreBuild event)                            ␊
     ────────────────────────────────────────────────────────────────␊
     ␊
     JavaScript␊
     ␊
-    (./plugin onPreBuild completed in 1ms)␊
+    (./plugin.cjs onPreBuild completed in 1ms)␊
     ␊
     ────────────────────────────────────────────────────────────────␊
       Netlify Build Complete                                        ␊
diff --git a/packages/build/tests/plugins/snapshots/tests.mjs.snap b/packages/build/tests/plugins/snapshots/tests.mjs.snap
index 6d96162640..f1afda93a5 100644
Binary files a/packages/build/tests/plugins/snapshots/tests.mjs.snap and b/packages/build/tests/plugins/snapshots/tests.mjs.snap differ
diff --git a/packages/build/tests/telemetry/tests.mjs b/packages/build/tests/telemetry/tests.mjs
index f8545236b1..e521e4763c 100644
--- a/packages/build/tests/telemetry/tests.mjs
+++ b/packages/build/tests/telemetry/tests.mjs
@@ -222,9 +222,11 @@ test('Telemetry calls timeout by default', async (t) => {
     // We want to rely on the default timeout value
     disableTelemetryTimeout: false,
     // Introduce an arbitrary large timeout on the server side so that we can validate the client timeout works
-    waitTelemetryServer: 5 * 60 * 1000,
+    waitTelemetryServer: WAIT_TELEMETRY_SERVER,
     // The error monitor snapshot should contain the timeout error
     snapshot: true,
   })
   t.is(telemetryRequests.length, 0)
 })
+
+const WAIT_TELEMETRY_SERVER = 3e5