diff --git a/.eslintrc b/.eslintrc
new file mode 100644
index 0000000..ac6ca88
--- /dev/null
+++ b/.eslintrc
@@ -0,0 +1,21 @@
+{
+  "overrides": [
+    {
+      "files": "*.ts",
+      "parser": "@typescript-eslint/parser",
+      "rules": {
+        "no-unused-vars": "off",
+        "no-useless-constructor": "off",
+        "@typescript-eslint/no-unused-vars": "error",
+        "@typescript-eslint/no-useless-constructor": "error"
+      }
+    }
+  ],
+  "parserOptions": {
+    "ecmaVersion": 2018,
+    "sourceType": "module"
+  },
+  "plugins": [
+    "@typescript-eslint/eslint-plugin"
+  ]
+}
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 9c14fc9..fba38a3 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -43,3 +43,27 @@ jobs:
           PUPPETEER_SKIP_CHROMIUM_DOWNLOAD: true
       - run: npm test
       - run: npm run coverage
+  esm:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 14
+      - run: npm install
+      - run: npm run test:esm
+  deno:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v1
+        with:
+          node-version: 14
+      - run: npm install
+      - run: npm run compile
+      - uses: denolib/setup-deno@v2
+        with:
+          deno-version: v1.x
+      - run: |
+          deno --version
+          deno test test/deno/cliui-test.ts
diff --git a/.gitignore b/.gitignore
index eef5570..0028f33 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,4 +3,4 @@ node_modules
 .nyc_output
 package-lock.json
 coverage
-
+build
diff --git a/.nycrc b/.nycrc
index 827f9a7..73cd631 100644
--- a/.nycrc
+++ b/.nycrc
@@ -7,7 +7,7 @@
     "html",
     "text"
   ],
-  "lines": 98.0,
-  "branches": "98",
-  "statements": "98.0"
+  "lines": 99.0,
+  "branches": "95",
+  "statements": "99.0"
 }
diff --git a/README.md b/README.md
index b9a847f..65b5672 100644
--- a/README.md
+++ b/README.md
@@ -10,13 +10,13 @@ easily create complex multi-column command-line-interfaces.
 ## Example
 
 ```js
-var ui = require('cliui')()
+const ui = require('cliui')()
 
 ui.div('Usage: $0 [command] [options]')
 
 ui.div({
   text: 'Options:',
-  padding: [2, 0, 2, 0]
+  padding: [2, 0, 1, 0]
 })
 
 ui.div(
@@ -40,6 +40,32 @@ ui.div(
 console.log(ui.toString())
 ```
 
+## Deno/ESM Support
+
+As of `v7` `cliui` supports [Deno](https://github.com/denoland/deno) and
+[ESM](https://nodejs.org/api/esm.html#esm_ecmascript_modules):
+
+```typescript
+import cliui from "https://deno.land/x/cliui/deno.ts";
+
+const ui = cliui({})
+
+ui.div('Usage: $0 [command] [options]')
+
+ui.div({
+  text: 'Options:',
+  padding: [2, 0, 1, 0]
+})
+
+ui.div({
+  text: "-f, --file",
+  width: 20,
+  padding: [0, 4, 0, 4]
+})
+
+console.log(ui.toString())
+```
+
 <img width="500" src="screenshot.png">
 
 ## Layout DSL
diff --git a/deno.ts b/deno.ts
new file mode 100644
index 0000000..8adbc03
--- /dev/null
+++ b/deno.ts
@@ -0,0 +1,13 @@
+// Bootstrap cliui with CommonJS dependencies:
+import { cliui, UIOptions, UI } from './build/lib/index.js'
+import { wrap, stripAnsi } from './build/lib/string-utils.js'
+
+export default function ui (opts: UIOptions): UI {
+  return cliui(opts, {
+    stringWidth: (str: string) => {
+      return [...str].length
+    },
+    stripAnsi,
+    wrap
+  })
+}
diff --git a/index.mjs b/index.mjs
new file mode 100644
index 0000000..bc7a022
--- /dev/null
+++ b/index.mjs
@@ -0,0 +1,13 @@
+// Bootstrap cliui with CommonJS dependencies:
+import { cliui } from './build/lib/index.js'
+import { wrap, stripAnsi } from './build/lib/string-utils.js'
+
+export default function ui (opts) {
+  return cliui(opts, {
+    stringWidth: (str) => {
+      return [...str].length
+    },
+    stripAnsi,
+    wrap
+  })
+}
diff --git a/lib/cjs.ts b/lib/cjs.ts
new file mode 100644
index 0000000..bda4241
--- /dev/null
+++ b/lib/cjs.ts
@@ -0,0 +1,12 @@
+// Bootstrap cliui with CommonJS dependencies:
+import { cliui, UIOptions } from './index.js'
+const stringWidth = require('string-width')
+const stripAnsi = require('strip-ansi')
+const wrap = require('wrap-ansi')
+export default function ui (opts: UIOptions) {
+  return cliui(opts, {
+    stringWidth,
+    stripAnsi,
+    wrap
+  })
+}
diff --git a/index.js b/lib/index.ts
similarity index 64%
rename from index.js
rename to lib/index.ts
index e917b00..db5052e 100644
--- a/index.js
+++ b/lib/index.ts
@@ -1,26 +1,57 @@
 'use strict'
 
-const stringWidth = require('string-width')
-const stripAnsi = require('strip-ansi')
-const wrap = require('wrap-ansi')
-
 const align = {
   right: alignRight,
   center: alignCenter
 }
+
 const top = 0
 const right = 1
 const bottom = 2
 const left = 3
 
-class UI {
-  constructor (opts) {
+export interface UIOptions {
+  width: number;
+  wrap: boolean;
+  rows?: string[];
+}
+
+interface Column {
+  text: string;
+  width?: number;
+  align?: 'right'|'left'|'center',
+  padding: number[],
+  border?: boolean;
+}
+
+interface ColumnArray extends Array<Column> {
+  span: boolean;
+}
+
+interface Line {
+  hidden?: boolean;
+  text: string;
+  span?: boolean;
+}
+
+interface Mixin {
+  stringWidth: Function;
+  stripAnsi: Function;
+  wrap: Function;
+}
+
+export class UI {
+  width: number;
+  wrap: boolean;
+  rows: ColumnArray[];
+
+  constructor (opts: UIOptions) {
     this.width = opts.width
     this.wrap = opts.wrap
     this.rows = []
   }
 
-  span (...args) {
+  span (...args: ColumnArray) {
     const cols = this.div(...args)
     cols.span = true
   }
@@ -29,33 +60,32 @@ class UI {
     this.rows = []
   }
 
-  div (...args) {
+  div (...args: (Column|string)[]): ColumnArray {
     if (args.length === 0) {
       this.div('')
     }
 
-    if (this.wrap && this._shouldApplyLayoutDSL(...args)) {
-      return this._applyLayoutDSL(args[0])
+    if (this.wrap && this.shouldApplyLayoutDSL(...args) && typeof args[0] === 'string') {
+      return this.applyLayoutDSL(args[0])
     }
 
     const cols = args.map(arg => {
       if (typeof arg === 'string') {
-        return this._colFromString(arg)
+        return this.colFromString(arg)
       }
-
       return arg
-    })
+    }) as ColumnArray
 
     this.rows.push(cols)
     return cols
   }
 
-  _shouldApplyLayoutDSL (...args) {
+  private shouldApplyLayoutDSL (...args: (Column|string)[]): boolean {
     return args.length === 1 && typeof args[0] === 'string' &&
       /[\t\n]/.test(args[0])
   }
 
-  _applyLayoutDSL (str) {
+  private applyLayoutDSL (str: string): ColumnArray {
     const rows = str.split('\n').map(row => row.split('\t'))
     let leftColumnWidth = 0
 
@@ -64,10 +94,10 @@ class UI {
     // don't allow the first column to take up more
     // than 50% of the screen.
     rows.forEach(columns => {
-      if (columns.length > 1 && stringWidth(columns[0]) > leftColumnWidth) {
+      if (columns.length > 1 && mixin.stringWidth(columns[0]) > leftColumnWidth) {
         leftColumnWidth = Math.min(
           Math.floor(this.width * 0.5),
-          stringWidth(columns[0])
+          mixin.stringWidth(columns[0])
         )
       }
     })
@@ -79,30 +109,30 @@ class UI {
       this.div(...columns.map((r, i) => {
         return {
           text: r.trim(),
-          padding: this._measurePadding(r),
+          padding: this.measurePadding(r),
           width: (i === 0 && columns.length > 1) ? leftColumnWidth : undefined
-        }
+        } as Column
       }))
     })
 
     return this.rows[this.rows.length - 1]
   }
 
-  _colFromString (text) {
+  private colFromString (text: string): Column {
     return {
       text,
-      padding: this._measurePadding(text)
+      padding: this.measurePadding(text)
     }
   }
 
-  _measurePadding (str) {
+  private measurePadding (str: string): number[] {
     // measure padding without ansi escape codes
-    const noAnsi = stripAnsi(str)
+    const noAnsi = mixin.stripAnsi(str)
     return [0, noAnsi.match(/\s*$/)[0].length, 0, noAnsi.match(/^\s*/)[0].length]
   }
 
-  toString () {
-    const lines = []
+  toString (): string {
+    const lines: Line[] = []
 
     this.rows.forEach(row => {
       this.rowToString(row, lines)
@@ -116,24 +146,25 @@ class UI {
       .join('\n')
   }
 
-  rowToString (row, lines) {
-    this._rasterize(row).forEach((rrow, r) => {
+  rowToString (row: ColumnArray, lines: Line[]) {
+    this.rasterize(row).forEach((rrow, r) => {
       let str = ''
-      rrow.forEach((col, c) => {
+      rrow.forEach((col: string, c: number) => {
         const { width } = row[c] // the width with padding.
-        const wrapWidth = this._negatePadding(row[c]) // the width without padding.
+        const wrapWidth = this.negatePadding(row[c]) // the width without padding.
 
         let ts = col // temporary string used during alignment/padding.
 
-        if (wrapWidth > stringWidth(col)) {
-          ts += ' '.repeat(wrapWidth - stringWidth(col))
+        if (wrapWidth > mixin.stringWidth(col)) {
+          ts += ' '.repeat(wrapWidth - mixin.stringWidth(col))
         }
 
         // align the string within its column.
         if (row[c].align && row[c].align !== 'left' && this.wrap) {
-          ts = align[row[c].align](ts, wrapWidth)
-          if (stringWidth(ts) < wrapWidth) {
-            ts += ' '.repeat(width - stringWidth(ts) - 1)
+          const fn = align[(row[c].align as 'right'|'center')]
+          ts = fn(ts, wrapWidth)
+          if (mixin.stringWidth(ts) < wrapWidth) {
+            ts += ' '.repeat((width || 0) - mixin.stringWidth(ts) - 1)
           }
         }
 
@@ -153,7 +184,7 @@ class UI {
         // if prior row is span, try to render the
         // current row on the prior line.
         if (r === 0 && lines.length > 0) {
-          str = this._renderInline(str, lines[lines.length - 1])
+          str = this.renderInline(str, lines[lines.length - 1])
         }
       })
 
@@ -169,10 +200,11 @@ class UI {
 
   // if the full 'source' can render in
   // the target line, do so.
-  _renderInline (source, previousLine) {
-    const leadingWhitespace = source.match(/^ */)[0].length
+  private renderInline (source: string, previousLine: Line) {
+    const match = source.match(/^ */)
+    const leadingWhitespace = match ? match[0].length : 0
     const target = previousLine.text
-    const targetTextWidth = stringWidth(target.trimRight())
+    const targetTextWidth = mixin.stringWidth(target.trimRight())
 
     if (!previousLine.span) {
       return source
@@ -194,9 +226,9 @@ class UI {
     return target.trimRight() + ' '.repeat(leadingWhitespace - targetTextWidth) + source.trimLeft()
   }
 
-  _rasterize (row) {
-    const rrows = []
-    const widths = this._columnWidths(row)
+  private rasterize (row: ColumnArray) {
+    const rrows: string[][] = []
+    const widths = this.columnWidths(row)
     let wrapped
 
     // word wrap all columns, and create
@@ -205,14 +237,14 @@ class UI {
       // leave room for left and right padding.
       col.width = widths[c]
       if (this.wrap) {
-        wrapped = wrap(col.text, this._negatePadding(col), { hard: true }).split('\n')
+        wrapped = mixin.wrap(col.text, this.negatePadding(col), { hard: true }).split('\n')
       } else {
         wrapped = col.text.split('\n')
       }
 
       if (col.border) {
-        wrapped.unshift('.' + '-'.repeat(this._negatePadding(col) + 2) + '.')
-        wrapped.push("'" + '-'.repeat(this._negatePadding(col) + 2) + "'")
+        wrapped.unshift('.' + '-'.repeat(this.negatePadding(col) + 2) + '.')
+        wrapped.push("'" + '-'.repeat(this.negatePadding(col) + 2) + "'")
       }
 
       // add top and bottom padding.
@@ -221,7 +253,7 @@ class UI {
         wrapped.push(...new Array(col.padding[bottom] || 0).fill(''))
       }
 
-      wrapped.forEach((str, r) => {
+      wrapped.forEach((str: string, r: number) => {
         if (!rrows[r]) {
           rrows.push([])
         }
@@ -241,8 +273,8 @@ class UI {
     return rrows
   }
 
-  _negatePadding (col) {
-    let wrapWidth = col.width
+  private negatePadding (col: Column) {
+    let wrapWidth = col.width || 0
     if (col.padding) {
       wrapWidth -= (col.padding[left] || 0) + (col.padding[right] || 0)
     }
@@ -254,10 +286,10 @@ class UI {
     return wrapWidth
   }
 
-  _columnWidths (row) {
+  private columnWidths (row: ColumnArray) {
     if (!this.wrap) {
       return row.map(col => {
-        return col.width || stringWidth(col.text)
+        return col.width || mixin.stringWidth(col.text)
       })
     }
 
@@ -288,7 +320,7 @@ class UI {
   }
 }
 
-function addBorder (col, ts, style) {
+function addBorder (col: Column, ts: string, style: string) {
   if (col.border) {
     if (/[.']-+[.']/.test(ts)) {
       return ''
@@ -306,7 +338,7 @@ function addBorder (col, ts, style) {
 
 // calculates the minimum width of
 // a column, based on padding preferences.
-function _minWidth (col) {
+function _minWidth (col: Column) {
   const padding = col.padding || []
   const minWidth = 1 + (padding[left] || 0) + (padding[right] || 0)
   if (col.border) {
@@ -316,16 +348,17 @@ function _minWidth (col) {
   return minWidth
 }
 
-function getWindowWidth () {
+function getWindowWidth (): number {
   /* istanbul ignore next: depends on terminal */
   if (typeof process === 'object' && process.stdout && process.stdout.columns) {
     return process.stdout.columns
   }
+  return 80
 }
 
-function alignRight (str, width) {
+function alignRight (str: string, width: number): string {
   str = str.trim()
-  const strWidth = stringWidth(str)
+  const strWidth = mixin.stringWidth(str)
 
   if (strWidth < width) {
     return ' '.repeat(width - strWidth) + str
@@ -334,9 +367,9 @@ function alignRight (str, width) {
   return str
 }
 
-function alignCenter (str, width) {
+function alignCenter (str: string, width: number): string {
   str = str.trim()
-  const strWidth = stringWidth(str)
+  const strWidth = mixin.stringWidth(str)
 
   /* istanbul ignore next */
   if (strWidth >= width) {
@@ -346,9 +379,11 @@ function alignCenter (str, width) {
   return ' '.repeat((width - strWidth) >> 1) + str
 }
 
-module.exports = function (opts = {}) {
+let mixin: Mixin
+export function cliui (opts: Partial<UIOptions> = {}, _mixin: Mixin) {
+  mixin = _mixin
   return new UI({
-    width: opts.width || getWindowWidth() || /* istanbul ignore next */ 80,
+    width: opts.width || getWindowWidth(),
     wrap: opts.wrap !== false
   })
 }
diff --git a/lib/string-utils.ts b/lib/string-utils.ts
new file mode 100644
index 0000000..23d78fd
--- /dev/null
+++ b/lib/string-utils.ts
@@ -0,0 +1,30 @@
+// Minimal replacement for ansi string helpers "wrap-ansi" and "strip-ansi".
+// to facilitate ESM and Deno modules.
+// TODO: look at porting https://www.npmjs.com/package/wrap-ansi to ESM.
+
+// The npm application
+// Copyright (c) npm, Inc. and Contributors
+// Licensed on the terms of The Artistic License 2.0
+// See: https://github.com/npm/cli/blob/4c65cd952bc8627811735bea76b9b110cc4fc80e/lib/utils/ansi-trim.js
+const ansi = new RegExp('\x1b(?:\\[(?:\\d+[ABCDEFGJKSTm]|\\d+;\\d+[Hfm]|' +
+'\\d+;\\d+;\\d+m|6n|s|u|\\?25[lh])|\\w)', 'g')
+
+export function stripAnsi (str: string) {
+  return str.replace(ansi, '')
+}
+
+export function wrap (str: string, width: number) {
+  const [start, end] = str.match(ansi) || ['', '']
+  str = stripAnsi(str)
+  let wrapped = ''
+  for (let i = 0; i < str.length; i++) {
+    if (i !== 0 && (i % width) === 0) {
+      wrapped += '\n'
+    }
+    wrapped += str.charAt(i)
+  }
+  if (start && end) {
+    wrapped = `${start}${wrapped}${end}`
+  }
+  return wrapped
+}
diff --git a/package.json b/package.json
index 90bfd23..1f4bab7 100644
--- a/package.json
+++ b/package.json
@@ -3,11 +3,26 @@
   "version": "6.0.0",
   "description": "easily create complex multi-column command-line-interfaces",
   "main": "index.js",
+  "exports": {
+    "import": "./index.mjs",
+    "require": "./build/index.cjs"
+  },
+  "type": "module",
+  "module": "./index.mjs",
   "scripts": {
-    "fix": "standard --fix",
-    "test": "c8 mocha",
-    "posttest": "standard",
-    "coverage": "c8 report --check-coverage"
+    "check": "standardx '**/*.ts' && standardx '**/*.js' && standardx '**/*.cjs'",
+    "fix": "standardx --fix '**/*.ts' && standardx --fix '**/*.js' && standardx --fix '**/*.cjs'",
+    "pretest": "rimraf build && tsc -p tsconfig.test.json && cross-env NODE_ENV=test npm run build:cjs",
+    "test": "c8 mocha ./test/*.cjs",
+    "test:esm": "c8 mocha ./test/esm/cliui-test.mjs",
+    "postest": "check",
+    "posttest": "npm run check",
+    "coverage": "c8 report --check-coverage",
+    "precompile": "rimraf build",
+    "compile": "tsc",
+    "postcompile": "npm run build:cjs",
+    "build:cjs": "rollup -c",
+    "prepare": "npm run compile"
   },
   "repository": {
     "type": "git",
@@ -38,14 +53,27 @@
     "wrap-ansi": "^7.0.0"
   },
   "devDependencies": {
+    "@typescript-eslint/eslint-plugin": "^3.8.0",
+    "@typescript-eslint/parser": "^3.8.0",
+    "@wessberg/rollup-plugin-ts": "^1.3.2",
     "c8": "^7.3.0",
     "chai": "^4.2.0",
     "chalk": "^4.1.0",
+    "cross-env": "^7.0.2",
+    "eslint": "^7.6.0",
+    "eslint-plugin-import": "^2.22.0",
+    "eslint-plugin-node": "^11.1.0",
+    "gts": "^2.0.2",
     "mocha": "^8.1.1",
-    "standard": "^14.3.4"
+    "rimraf": "^3.0.2",
+    "rollup": "^2.23.1",
+    "standardx": "^5.0.0",
+    "typescript": "^3.9.7"
   },
   "files": [
-    "index.js"
+    "build",
+    "index.mjs",
+    "!*.d.ts"
   ],
   "engine": {
     "node": ">=10"
diff --git a/rollup.config.js b/rollup.config.js
new file mode 100644
index 0000000..ec8a2ac
--- /dev/null
+++ b/rollup.config.js
@@ -0,0 +1,17 @@
+import ts from '@wessberg/rollup-plugin-ts'
+
+const output = {
+  format: 'cjs',
+  file: './build/index.cjs',
+  exports: 'default'
+}
+
+if (process.env.NODE_ENV === 'test') output.sourcemap = true
+
+export default {
+  input: './lib/cjs.ts',
+  output,
+  plugins: [
+    ts({ /* options */ })
+  ]
+}
diff --git a/test/cliui.js b/test/cliui.cjs
similarity index 97%
rename from test/cliui.js
rename to test/cliui.cjs
index e9752a8..6dd86e7 100644
--- a/test/cliui.js
+++ b/test/cliui.cjs
@@ -8,7 +8,7 @@ require('chai').should()
 process.env.FORCE_COLOR = 1
 
 const chalk = require('chalk')
-const cliui = require('../')
+const cliui = require('../build/index.cjs')
 const stripAnsi = require('strip-ansi')
 
 describe('cliui', () => {
@@ -82,7 +82,7 @@ describe('cliui', () => {
       const ui = cliui({
         width: 40
       })
-      const widths = ui._columnWidths([{}, {}, {}])
+      const widths = ui.columnWidths([{}, {}, {}])
 
       widths[0].should.equal(13)
       widths[1].should.equal(13)
@@ -93,7 +93,7 @@ describe('cliui', () => {
       const ui = cliui({
         width: 40
       })
-      const widths = ui._columnWidths([{ width: 20 }, {}, {}])
+      const widths = ui.columnWidths([{ width: 20 }, {}, {}])
 
       widths[0].should.equal(20)
       widths[1].should.equal(10)
@@ -104,7 +104,7 @@ describe('cliui', () => {
       const ui = cliui({
         width: 40
       })
-      const widths = ui._columnWidths([{}, { width: 10 }, {}])
+      const widths = ui.columnWidths([{}, { width: 10 }, {}])
 
       widths[0].should.equal(15)
       widths[1].should.equal(10)
@@ -115,7 +115,7 @@ describe('cliui', () => {
       const ui = cliui({
         width: 40
       })
-      const widths = ui._columnWidths([{ width: 20 }, { width: 12 }, {}])
+      const widths = ui.columnWidths([{ width: 20 }, { width: 12 }, {}])
 
       widths[0].should.equal(20)
       widths[1].should.equal(12)
@@ -126,7 +126,7 @@ describe('cliui', () => {
       const ui = cliui({
         width: 40
       })
-      const widths = ui._columnWidths([{ width: 30 }, { width: 30 }, { padding: [0, 2, 0, 1] }])
+      const widths = ui.columnWidths([{ width: 30 }, { width: 30 }, { padding: [0, 2, 0, 1] }])
 
       widths[0].should.equal(30)
       widths[1].should.equal(30)
diff --git a/test/deno/cliui-test.ts b/test/deno/cliui-test.ts
new file mode 100644
index 0000000..ce24068
--- /dev/null
+++ b/test/deno/cliui-test.ts
@@ -0,0 +1,51 @@
+/* global Deno */
+
+import {
+  assert,
+  assertEquals
+} from 'https://deno.land/std/testing/asserts.ts'
+import cliui from '../../deno.ts'
+
+Deno.test("wraps text at 'width' if a single column is given", () => {
+  const ui = cliui({
+    width: 10
+  })
+
+  ui.div('i am a string that should be wrapped')
+
+  ui.toString().split('\n').forEach((row: string) => {
+    assert(row.length <= 10)
+  })
+})
+
+Deno.test('evenly divides text across columns if multiple columns are given', () => {
+  const ui = cliui({
+    width: 40
+  })
+
+  ui.div(
+    { text: 'i am a string that should be wrapped', width: 15 },
+    'i am a second string that should be wrapped',
+    'i am a third string that should be wrapped'
+  )
+
+  // total width of all columns is <=
+  // the width cliui is initialized with.
+  ui.toString().split('\n').forEach((row: string) => {
+    assert(row.length <= 40)
+  })
+
+  // it should wrap each column appropriately.
+  // TODO: we should flesh out the Deno and ESM implementation
+  // such that it spreads words out over multiple columns appropriately:
+  const expected = [
+    'i am a string ti am a seconi am a third',
+    'hat should be wd string tha string that',
+    'rapped         t should be  should be w',
+    '               wrapped     rapped'
+  ]
+
+  ui.toString().split('\n').forEach((line: string, i: number) => {
+    assertEquals(line, expected[i])
+  })
+})
diff --git a/test/esm/cliui-test.mjs b/test/esm/cliui-test.mjs
new file mode 100644
index 0000000..f57d77d
--- /dev/null
+++ b/test/esm/cliui-test.mjs
@@ -0,0 +1,47 @@
+import {ok as assert, strictEqual} from 'assert'
+import cliui from '../../index.mjs'
+
+describe('ESM', () => {
+  it("wraps text at 'width' if a single column is given", () => {
+    const ui = cliui({
+      width: 10
+    })
+
+    ui.div('i am a string that should be wrapped')
+
+    ui.toString().split('\n').forEach((row) => {
+      assert(row.length <= 10)
+    })
+  })
+
+  it('evenly divides text across columns if multiple columns are given', () => {
+    const ui = cliui({
+      width: 40
+    })
+
+    ui.div(
+      { text: 'i am a string that should be wrapped', width: 15 },
+      'i am a second string that should be wrapped',
+      'i am a third string that should be wrapped'
+    )
+
+    // total width of all columns is <=
+    // the width cliui is initialized with.
+    ui.toString().split('\n').forEach((row) => {
+      assert(row.length <= 40)
+    })
+
+    // it should wrap each column appropriately.
+    // TODO: we should flesh out the Deno and ESM implementation
+    // such that it spreads words out over multiple columns appropriately:
+    const expected = [
+      'i am a string ti am a seconi am a third',
+      'hat should be wd string tha string that',
+      'rapped         t should be  should be w',
+      '               wrapped     rapped'
+    ]
+    ui.toString().split('\n').forEach((line, i) => {
+      strictEqual(line, expected[i])
+    })
+  })
+})
\ No newline at end of file
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..d5d8c21
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,17 @@
+{
+  "extends": "./node_modules/gts/tsconfig-google.json",
+  "compilerOptions": {
+    "outDir": "build",
+    "rootDir": ".",
+    "sourceMap": false,
+    "target": "es2017",
+    "moduleResolution": "node",
+    "module": "es2015"
+  },  
+  "include": [
+    "lib/**/*.ts"
+  ],
+  "exclude": [
+    "lib/cjs.ts"
+  ]
+}
\ No newline at end of file
diff --git a/tsconfig.test.json b/tsconfig.test.json
new file mode 100644
index 0000000..bc078f4
--- /dev/null
+++ b/tsconfig.test.json
@@ -0,0 +1,6 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "sourceMap": true
+  }
+}
\ No newline at end of file