diff --git a/.eslintrc.js b/.eslintrc.js
index ccc0b3249bdf..32eb83986453 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -11,8 +11,10 @@ module.exports = {
   },
   parser: "@typescript-eslint/parser",
   parserOptions: {
-    ecmaVersion: 10,
+    ecmaVersion: "latest",
     project: "./tsconfig.json",
+    // Support ESM modules
+    sourceType: "module",
   },
   plugins: ["@typescript-eslint", "eslint-plugin-import", "eslint-plugin-node", "no-only-tests", "prettier"],
   extends: [
@@ -124,6 +126,9 @@ module.exports = {
 
     // Prevents accidentally pushing a commit with .only in Mocha tests
     "no-only-tests/no-only-tests": "error",
+
+    // TEMP Disabled while eslint-plugin-import support ESM (Typescript does support it) https://github.com/import-js/eslint-plugin-import/issues/2170
+    "import/no-unresolved": "off",
   },
   overrides: [
     {
diff --git a/packages/utils/package.json b/packages/utils/package.json
index ddbdd6135e22..26eaf0940a44 100644
--- a/packages/utils/package.json
+++ b/packages/utils/package.json
@@ -12,6 +12,8 @@
     "url": "https://github.com/ChainSafe/lodestar/issues"
   },
   "version": "0.29.3",
+  "type": "module",
+  "exports": "./lib/index.js",
   "main": "lib/index.js",
   "files": [
     "lib/**/*.d.ts",
@@ -20,6 +22,9 @@
     "*.d.ts",
     "*.js"
   ],
+  "engines": {
+    "node": "^12.20.0 || ^14.13.1 || >=16.0.0"
+  },
   "scripts": {
     "clean": "rm -rf lib && rm -f *.tsbuildinfo",
     "build": "tsc -p tsconfig.build.json",
diff --git a/packages/utils/src/index.ts b/packages/utils/src/index.ts
index 4fbe38e12dad..295566f54474 100644
--- a/packages/utils/src/index.ts
+++ b/packages/utils/src/index.ts
@@ -1,15 +1,15 @@
-export * from "./logger";
-export * from "./yaml";
-export * from "./assert";
-export * from "./bytes";
-export * from "./errors";
-export * from "./format";
-export * from "./math";
-export * from "./objects";
-export * from "./notNullish";
-export * from "./sleep";
-export * from "./sort";
-export * from "./timeout";
-export * from "./types";
-export * from "./verifyMerkleBranch";
-export * from "./json";
+export * from "./logger/index.js";
+export * from "./yaml/index.js";
+export * from "./assert.js";
+export * from "./bytes.js";
+export * from "./errors.js";
+export * from "./format.js";
+export * from "./math.js";
+export * from "./objects.js";
+export * from "./notNullish.js";
+export * from "./sleep.js";
+export * from "./sort.js";
+export * from "./timeout.js";
+export * from "./types.js";
+export * from "./verifyMerkleBranch.js";
+export * from "./json.js";
diff --git a/packages/utils/src/json.ts b/packages/utils/src/json.ts
index 1aefa1a5f97d..ed906b16132c 100644
--- a/packages/utils/src/json.ts
+++ b/packages/utils/src/json.ts
@@ -1,6 +1,6 @@
 import {Json, toHexString} from "@chainsafe/ssz";
-import {LodestarError} from "./errors";
-import {mapValues} from "./objects";
+import {LodestarError} from "./errors.js";
+import {mapValues} from "./objects.js";
 
 export const CIRCULAR_REFERENCE_TAG = "CIRCULAR_REFERENCE";
 
diff --git a/packages/utils/src/logger/format.ts b/packages/utils/src/logger/format.ts
index 3a44f8b48ae1..6f5d7ab1f6fe 100644
--- a/packages/utils/src/logger/format.ts
+++ b/packages/utils/src/logger/format.ts
@@ -1,6 +1,6 @@
 import {Json} from "@chainsafe/ssz";
 import {format} from "winston";
-import {toJson, toString} from "../json";
+import {toJson, toString} from "../json.js";
 import {Context, ILoggerOptions, TimestampFormatCode} from "./interface";
 import {formatEpochSlotTime} from "./util";
 
diff --git a/packages/utils/src/logger/index.ts b/packages/utils/src/logger/index.ts
index 33c9eefc9db8..5cb88279c696 100644
--- a/packages/utils/src/logger/index.ts
+++ b/packages/utils/src/logger/index.ts
@@ -3,6 +3,6 @@
  */
 
 export * from "./interface";
-export * from "./format";
-export * from "./transport";
-export * from "./winston";
+export * from "./format.js";
+export * from "./transport.js";
+export * from "./winston.js";
diff --git a/packages/utils/src/logger/winston.ts b/packages/utils/src/logger/winston.ts
index 3623caee9107..e095d6132a63 100644
--- a/packages/utils/src/logger/winston.ts
+++ b/packages/utils/src/logger/winston.ts
@@ -5,9 +5,9 @@
 import {createLogger, Logger} from "winston";
 import {Context, defaultLogLevel, ILogger, ILoggerOptions, LogLevel, logLevelNum} from "./interface";
 import chalk from "chalk";
-import {getFormat} from "./format";
+import {getFormat} from "./format.js";
 import {Writable} from "stream";
-import {TransportOpts, TransportType, fromTransportOpts} from "./transport";
+import {TransportOpts, TransportType, fromTransportOpts} from "./transport.js";
 
 const defaultTransportOpts: TransportOpts = {type: TransportType.console};
 
diff --git a/packages/utils/src/sleep.ts b/packages/utils/src/sleep.ts
index 0134bf23810d..16d482eec159 100644
--- a/packages/utils/src/sleep.ts
+++ b/packages/utils/src/sleep.ts
@@ -1,5 +1,5 @@
 import {AbortSignal} from "@chainsafe/abort-controller";
-import {ErrorAborted} from "./errors";
+import {ErrorAborted} from "./errors.js";
 
 /**
  * Abortable sleep function. Cleans everything on all cases preventing leaks
diff --git a/packages/utils/src/timeout.ts b/packages/utils/src/timeout.ts
index 8545152bfbf5..c3d5f4d485c7 100644
--- a/packages/utils/src/timeout.ts
+++ b/packages/utils/src/timeout.ts
@@ -1,7 +1,7 @@
 import {AbortSignal, AbortController} from "@chainsafe/abort-controller";
 import {anySignal} from "any-signal";
-import {TimeoutError} from "./errors";
-import {sleep} from "./sleep";
+import {TimeoutError} from "./errors.js";
+import {sleep} from "./sleep.js";
 
 export async function withTimeout<T>(
   asyncFn: (timeoutAndParentSignal?: AbortSignal) => Promise<T>,
diff --git a/packages/utils/src/verifyMerkleBranch.ts b/packages/utils/src/verifyMerkleBranch.ts
index 59db928575bf..7cbce3d6d10d 100644
--- a/packages/utils/src/verifyMerkleBranch.ts
+++ b/packages/utils/src/verifyMerkleBranch.ts
@@ -1,4 +1,3 @@
-import {intDiv} from "./math";
 import {hash} from "@chainsafe/ssz";
 
 /**
@@ -14,7 +13,7 @@ export function verifyMerkleBranch(
 ): boolean {
   let value = leaf;
   for (let i = 0; i < depth; i++) {
-    if (intDiv(index, 2 ** i) % 2) {
+    if (Math.floor(index / 2 ** i) % 2) {
       value = hash(Buffer.concat([proof[i], value]));
     } else {
       value = hash(Buffer.concat([value, proof[i]]));
diff --git a/packages/utils/src/yaml/index.ts b/packages/utils/src/yaml/index.ts
index ac0cb1394edc..e5908d5a89fb 100644
--- a/packages/utils/src/yaml/index.ts
+++ b/packages/utils/src/yaml/index.ts
@@ -1,6 +1,6 @@
 import {load, dump} from "js-yaml";
-import {schema} from "./schema";
-import {objectToExpectedCase} from "../objects";
+import {schema} from "./schema.js";
+import {objectToExpectedCase} from "../objects.js";
 
 export function loadYaml(yaml: string): Record<string, unknown> {
   return objectToExpectedCase<Record<string, unknown>>(load(yaml, {schema}));
diff --git a/packages/utils/src/yaml/schema.ts b/packages/utils/src/yaml/schema.ts
index efe59c4f4405..03ef475ab5f0 100644
--- a/packages/utils/src/yaml/schema.ts
+++ b/packages/utils/src/yaml/schema.ts
@@ -11,7 +11,7 @@ import boolType from "js-yaml/lib/js-yaml/type/bool";
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
 // @ts-ignore
 import floatType from "js-yaml/lib/js-yaml/type/float";
-import {intType} from "./int";
+import {intType} from "./int.js";
 
 export const schema = new Schema({
   include: [failsafe],
diff --git a/packages/utils/tsconfig.build.json b/packages/utils/tsconfig.build.json
index bac394399f4e..5395232e2eea 100644
--- a/packages/utils/tsconfig.build.json
+++ b/packages/utils/tsconfig.build.json
@@ -2,6 +2,10 @@
   "extends": "../../tsconfig.build.json",
   "include": ["src"],
   "compilerOptions": {
-    "outDir": "./lib"
+    "outDir": "./lib",
+    "target": "es2020",
+    "module": "esnext",
+    "moduleResolution": "Node",
+    "allowSyntheticDefaultImports": true
   }
 }
diff --git a/packages/utils/tsconfig.json b/packages/utils/tsconfig.json
index b29a7b46c4b1..c5fd0b35329f 100644
--- a/packages/utils/tsconfig.json
+++ b/packages/utils/tsconfig.json
@@ -1,4 +1,9 @@
 {
   "extends": "../../tsconfig.json",
-  "compilerOptions": {}
+  "compilerOptions": {
+    "target": "es2020",
+    "module": "ES2020",
+    "moduleResolution": "Node",
+    "allowSyntheticDefaultImports": true
+  }
 }