diff --git a/.eslintrc.cjs b/.eslintrc.cjs
new file mode 100644
index 0000000..9fae717
--- /dev/null
+++ b/.eslintrc.cjs
@@ -0,0 +1,38 @@
+"use strict"
+
+const [, , error] = ["off", "warn", "error"]
+
+module.exports = {
+  extends: ["./node_modules/ts-standardx/.eslintrc.js"],
+  ignorePatterns: ["dist"],
+  rules: {
+    "no-unused-vars": [
+      error,
+      {
+        argsIgnorePattern: "^_",
+        caughtErrorsIgnorePattern: "^_",
+        varsIgnorePattern: "^_"
+      }
+    ],
+    quotes: [error, "double"],
+
+    "prettier/prettier": [
+      error,
+      {
+        semi: false,
+        singleQuote: false,
+        trailingComma: "none",
+        bracketSameLine: true,
+        arrowParens: "avoid"
+      }
+    ]
+  },
+  overrides: [
+    {
+      files: ["**/*.{ts,tsx}"],
+      rules: {
+        "@typescript-eslint/quotes": [error, "double"]
+      }
+    }
+  ]
+}
diff --git a/.gitignore b/.gitignore
index 3585ab8..3af49db 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,5 @@ package-lock.json
 yarn.lock
 
 node_modules
+
+/dist
diff --git a/ava.config.js b/ava.config.js
new file mode 100644
index 0000000..3da3170
--- /dev/null
+++ b/ava.config.js
@@ -0,0 +1,10 @@
+export default {
+  extensions: {
+    ts: "module"
+  },
+  nonSemVerExperiments: {
+    configurableModuleFormat: true,
+    nextGenConfig: true
+  },
+  nodeArguments: ["--loader=ts-node/esm"]
+}
diff --git a/declarations.d.ts b/declarations.d.ts
new file mode 100644
index 0000000..91eb7a2
--- /dev/null
+++ b/declarations.d.ts
@@ -0,0 +1,9 @@
+declare module "split-text-to-chunks" {
+  interface Split {
+    width: (text: string, max: number) => number
+    (text: string, columns: number): string
+  }
+
+  const split: Split
+  export default split
+}
diff --git a/fixtures/inputs.js b/fixtures/inputs.js
deleted file mode 100644
index b841cbb..0000000
--- a/fixtures/inputs.js
+++ /dev/null
@@ -1,197 +0,0 @@
-'use strict'
-
-const { EOL } = require('os')
-
-module.exports = {
-  standard: {
-    input: [
-      {
-        name: 'trilogy',
-        repo: '[citycide/trilogy](//github.com/citycide/trilogy)',
-        desc: 'No-hassle SQLite with type-casting schema models and support for native & pure JS backends.'
-      },
-      {
-        name: 'strat',
-        repo: '[citycide/strat](//github.com/citycide/strat)',
-        desc: 'Functional-ish JavaScript string formatting, with inspirations from Python.'
-      },
-      {
-        name: 'tablemark',
-        repo: '[citycide/tablemark](//github.com/citycide/tablemark)',
-        desc: 'Generate markdown tables from JSON data.'
-      }
-    ],
-    expected: [
-      '| Name      | Repo                                                  | Desc                                                                                        |',
-      '| --------- | ----------------------------------------------------- | ------------------------------------------------------------------------------------------- |',
-      '| trilogy   | [citycide/trilogy](//github.com/citycide/trilogy)     | No-hassle SQLite with type-casting schema models and support for native & pure JS backends. |',
-      '| strat     | [citycide/strat](//github.com/citycide/strat)         | Functional-ish JavaScript string formatting, with inspirations from Python.                 |',
-      '| tablemark | [citycide/tablemark](//github.com/citycide/tablemark) | Generate markdown tables from JSON data.                                                    |'
-    ].join(EOL) + EOL
-  },
-  alignments: {
-    input: [
-      { name: 'Bob', age: 21, isCool: false },
-      { name: 'Sarah', age: 22, isCool: true },
-      { name: 'Lee', age: 23, isCool: true }
-    ],
-    options: {
-      columns: [
-        { align: 'left' },
-        { align: 'right' },
-        { align: 'center' }
-      ]
-    },
-    expected: [
-      '| Name  |   Age | Is cool |',
-      '| :---- | ----: | :-----: |',
-      '| Bob   |    21 |  false  |',
-      '| Sarah |    22 |  true   |',
-      '| Lee   |    23 |  true   |'
-    ].join(EOL) + EOL
-  },
-  columns: {
-    input: [
-      { name: 'Bob', age: 21, isCool: false },
-      { name: 'Sarah', age: 22, isCool: true },
-      { name: 'Lee', age: 23, isCool: true }
-    ],
-    options: {
-      columns: [
-        { name: 'word' },
-        { name: 'number' },
-        { name: 'boolean' }
-      ]
-    },
-    expected: [
-      '| word  | number | boolean |',
-      '| ----- | ------ | ------- |',
-      '| Bob   | 21     | false   |',
-      '| Sarah | 22     | true    |',
-      '| Lee   | 23     | true    |'
-    ].join(EOL) + EOL
-  },
-  casing: {
-    input: [
-      { name: 'Bob', age: 21, isCool: false },
-      { name: 'Sarah', age: 22, isCool: true },
-      { name: 'Lee', age: 23, isCool: true }
-    ],
-    options: {
-      caseHeaders: false
-    },
-    expected: [
-      '| name  | age   | isCool |',
-      '| ----- | ----- | ------ |',
-      '| Bob   | 21    | false  |',
-      '| Sarah | 22    | true   |',
-      '| Lee   | 23    | true   |'
-    ].join(EOL) + EOL
-  },
-  coerce: {
-    input: [
-      { name: 'Bob', age: 21, isCool: false },
-      { name: 'Sarah', age: 22, isCool: true },
-      { name: 'Lee', age: 23, isCool: true }
-    ],
-    options: {
-      stringify (v) {
-        if (v === true) return 'Yes'
-        if (v === false) return 'No'
-        return String(v)
-      }
-    },
-    expected: [
-      '| Name  | Age   | Is cool |',
-      '| ----- | ----- | ------- |',
-      '| Bob   | 21    | No      |',
-      '| Sarah | 22    | Yes     |',
-      '| Lee   | 23    | Yes     |'
-    ].join(EOL) + EOL
-  },
-  wrap: {
-    input: [
-      { name: 'Benjamin', age: 21, isCool: false },
-      { name: 'Sarah', age: 22, isCool: true },
-      { name: 'Lee', age: 23, isCool: true }
-    ],
-    options: {
-      wrap: { width: 5 }
-    },
-    expected: [
-      // headers wrap, soft wrap
-      '| Name  | Age   | Is    |',
-      '                  cool   ',
-      '| ----- | ----- | ----- |',
-      // hard wrap
-      '| Benja | 21    | false |',
-      '  min                    ',
-      // no wrap
-      '| Sarah | 22    | true  |',
-      '| Lee   | 23    | true  |'
-    ].join(EOL) + EOL
-  },
-  newlines: {
-    input: [
-      { name: 'Benjamin\nor Ben', age: 21, isCool: false },
-      { name: 'Sarah', age: 22, isCool: true },
-      { name: 'Lee', age: 23, isCool: true }
-    ],
-    expected: [
-      '| Name     | Age   | Is cool |',
-      '| -------- | ----- | ------- |',
-      '| Benjamin | 21    | false   |',
-      '  or Ben                      ',
-      '| Sarah    | 22    | true    |',
-      '| Lee      | 23    | true    |'
-    ].join(EOL) + EOL
-  },
-  wrapAndNewlines: {
-    input: [
-      { name: 'Benjamin or\nBen', age: 21, isCool: false },
-      { name: 'Sarah', age: 22, isCool: true },
-      { name: 'Lee', age: 23, isCool: true }
-    ],
-    options: {
-      wrap: { width: 8 }
-    },
-    expected: [
-      '| Name     | Age   | Is cool |',
-      '| -------- | ----- | ------- |',
-      '| Benjamin | 21    | false   |',
-      '  or                          ',
-      '  Ben                         ',
-      '| Sarah    | 22    | true    |',
-      '| Lee      | 23    | true    |'
-    ].join(EOL) + EOL
-  },
-  gutters: {
-    input: [
-      { name: 'Benjamin', age: 21, isCool: false },
-      { name: 'Sarah', age: 22, isCool: true },
-      { name: 'Lee', age: 23, isCool: true }
-    ],
-    options: {
-      wrap: { width: 5, gutters: true }
-    },
-    expected: [
-      '| Name  | Age   | Is    |',
-      '|       |       | cool  |',
-      '| ----- | ----- | ----- |',
-      '| Benja | 21    | false |',
-      '| min   |       |       |',
-      '| Sarah | 22    | true  |',
-      '| Lee   | 23    | true  |'
-    ].join(EOL) + EOL
-  },
-  pipes: {
-    input: [
-      { content: 'yes | no' }
-    ],
-    expected: [
-      '| Content   |',
-      '| --------- |',
-      '| yes \\| no |'
-    ].join(EOL) + EOL
-  }
-}
diff --git a/index.d.ts b/index.d.ts
deleted file mode 100644
index 9af597d..0000000
--- a/index.d.ts
+++ /dev/null
@@ -1,25 +0,0 @@
-type InputData <T = Object> = (Iterable<T> | T)[]
-
-type ColumnDescriptor = string | {
-  align?: 'LEFT' | 'CENTER' | 'RIGHT'
-  name: string
-}
-
-interface StringifyFunction {
-  (value: any): string
-}
-
-interface WrapOptions {
-  gutter?: boolean,
-  width?: number
-}
-
-interface TablemarkOptions {
-  caseHeaders?: boolean,
-  columns?: ColumnDescriptor[],
-  stringify?: StringifyFunction,
-  wrap?: Partial<WrapOptions>
-}
-
-declare function tablemark <T> (input: InputData<T>, options?: TablemarkOptions): string
-export = tablemark
diff --git a/index.js b/index.js
deleted file mode 100644
index f782c20..0000000
--- a/index.js
+++ /dev/null
@@ -1,157 +0,0 @@
-'use strict'
-
-const { EOL } = require('os')
-const { sentenceCase } = require('sentence-case')
-const split = require('split-text-to-chunks')
-
-const { width } = split
-const columnsWidthMin = 5
-const alignmentOptions = new Set(['LEFT', 'CENTER', 'RIGHT'])
-const pipeRegex = /\|/g
-
-const pad = (alignment, width, content) => {
-  if (!alignment || alignment === 'LEFT') {
-    return content.padEnd(width)
-  }
-
-  if (alignment === 'RIGHT') {
-    return content.padStart(width)
-  }
-
-  // center alignment
-  const remainder = (width - content.length) % 2
-  const sides = (width - content.length - remainder) / 2
-
-  return ' '.repeat(sides) + content + ' '.repeat(sides + remainder)
-}
-
-const toString = v => {
-  if (typeof v === 'undefined') return ''
-  return String(v).replace(pipeRegex, '\\|')
-}
-
-const line = (columns, gutters) =>
-  (gutters ? '| ' : '  ') +
-  columns.join((gutters ? ' | ' : '   ')) +
-  (gutters ? ' |' : '  ') + EOL
-
-const row = (alignments, widths, columns, gutters) => {
-  const width = columns.length
-  const values = new Array(width)
-  const first = new Array(width)
-  let height = 1
-
-  for (let h = 0; h < width; h++) {
-    const cells = values[h] = split(columns[h], widths[h])
-    if (cells.length > height) height = cells.length
-    first[h] = pad(alignments[h], widths[h], cells[0])
-  }
-
-  if (height === 1) return line(first, true)
-
-  const lines = new Array(height)
-  lines[0] = line(first, true)
-
-  for (let v = 1; v < height; v++) {
-    lines[v] = new Array(width)
-  }
-
-  for (let h = 0; h < width; h++) {
-    const cells = values[h]
-    let v = 1
-
-    for (; v < cells.length; v++) {
-      lines[v][h] = pad(alignments[h], widths[h], cells[v])
-    }
-
-    for (; v < height; v++) {
-      lines[v][h] = ' '.repeat(widths[h])
-    }
-  }
-
-  for (let h = 1; h < height; h++) {
-    lines[h] = line(lines[h], gutters)
-  }
-
-  return lines.join('')
-}
-
-module.exports = (input, options) => {
-  if (!Array.isArray(input)) {
-    throw new TypeError(`Expected an Array, got ${typeof input}`)
-  }
-
-  options = Object.assign({
-    stringify: toString
-  }, options, {
-    wrap: Object.assign({
-      width: Infinity,
-      gutters: false
-    }, options && options.wrap)
-  })
-
-  const { stringify } = options
-  const { gutters, width: columnsMaxWidth } = options.wrap
-
-  const keys = Object.keys(input[0])
-
-  const titles = keys.map((key, i) => {
-    if (Array.isArray(options.columns) && options.columns[i]) {
-      if (typeof options.columns[i] === 'string') {
-        return options.columns[i]
-      } else if (options.columns[i].name) {
-        return options.columns[i].name
-      }
-    }
-
-    if (options.caseHeaders === false) return key
-
-    return sentenceCase(key)
-  })
-
-  const widths = input.reduce(
-    (sizes, item) => keys.map(
-      (key, i) => Math.max(width(stringify(item[key]), columnsMaxWidth), sizes[i])
-    ),
-    titles.map(t => Math.max(columnsWidthMin, width(t, columnsMaxWidth)))
-  )
-
-  const alignments = keys.map((key, i) => {
-    if (
-      Array.isArray(options.columns) &&
-      options.columns[i] &&
-      options.columns[i].align
-    ) {
-      const align = String(options.columns[i].align).toUpperCase()
-
-      if (!alignmentOptions.has(align)) {
-        throw new TypeError(`Unknown alignment, got ${options.columns[i].align}`)
-      }
-
-      return align
-    }
-  })
-
-  let table = ''
-
-  // header line
-  table += row(alignments, widths, titles, gutters)
-
-  // header separator
-  table += line(alignments.map(
-    (align, i) => (
-      (align === 'LEFT' || align === 'CENTER' ? ':' : '-') +
-      '-'.repeat(widths[i] - 2) +
-      (align === 'RIGHT' || align === 'CENTER' ? ':' : '-')
-    )
-  ), true)
-
-  // table body
-  table += input.map(
-    (item, i) => row(alignments, widths, keys.map(
-      key => stringify(item[key])
-    ), gutters)
-  ).join('')
-
-  return table
-}
diff --git a/package.json b/package.json
index 2a8d7a6..c5e2b6b 100644
--- a/package.json
+++ b/package.json
@@ -10,6 +10,9 @@
   "engines": {
     "node": ">=14.16"
   },
+  "type": "module",
+  "exports": "./dist/index.js",
+  "sideEffects": false,
   "keywords": [
     "markdown",
     "table",
@@ -18,26 +21,30 @@
     "convert",
     "generate",
     "ghfm",
-    "tableify"
+    "tableify",
+    "typescript"
   ],
   "files": [
-    "index.d.ts",
-    "index.js"
+    "dist"
   ],
   "scripts": {
-    "lint": "standard | snazzy",
+    "lint": "ts-standardx src && cd tests && ts-standardx .",
+    "build": "tsc",
+    "pretest": "npm run build",
     "test": "ava",
     "changelog": "changelog",
     "prepublishOnly": "npm run lint && npm test"
   },
   "devDependencies": {
     "@citycide/changelog": "^2.0.0",
-    "ava": "^3.8.1",
-    "snazzy": "^8.0.0",
-    "standard": "^14.3.3"
+    "@types/node": "^14.17.27",
+    "ava": "^3.15.0",
+    "ts-node": "^10.3.0",
+    "ts-standardx": "^0.8.4",
+    "typescript": "^4.4.4"
   },
   "dependencies": {
-    "sentence-case": "^3.0.3",
+    "sentence-case": "^3.0.4",
     "split-text-to-chunks": "^1.0.0"
   }
 }
diff --git a/src/index.ts b/src/index.ts
new file mode 100644
index 0000000..c17dd68
--- /dev/null
+++ b/src/index.ts
@@ -0,0 +1,67 @@
+import type { InputData, TablemarkOptions } from "./types.js"
+
+import {
+  getColumnAlignments,
+  getColumnTitles,
+  getColumnWidths,
+  line,
+  normalizeOptions,
+  row
+} from "./utilities.js"
+
+export const alignmentOptions = {
+  left: "LEFT",
+  center: "CENTER",
+  right: "RIGHT"
+} as const
+
+export default (input: InputData, options: TablemarkOptions = {}): string => {
+  if (typeof input[Symbol.iterator] !== "function") {
+    throw new TypeError(`Expected an iterable, got ${typeof input}`)
+  }
+
+  const config = normalizeOptions(options)
+
+  const keys = Object.keys(input[0])
+  const titles = getColumnTitles(keys, config)
+  const widths = getColumnWidths(input, keys, titles, config)
+  const alignments = getColumnAlignments(keys, config)
+
+  let table = ""
+
+  // header line
+  table += row(alignments, widths, titles, config)
+
+  // header separator
+  table += line(
+    alignments.map(
+      (align, i) =>
+        (align === alignmentOptions.left || align === alignmentOptions.center
+          ? ":"
+          : "-") +
+        "-".repeat(widths[i] - 2) +
+        (align === alignmentOptions.right || align === alignmentOptions.center
+          ? ":"
+          : "-")
+    ),
+    config,
+    true
+  )
+
+  // table body
+  table += input
+    .map((item, _) =>
+      row(
+        alignments,
+        widths,
+        keys.map(key => config.toCellText(item[key])),
+        config
+      )
+    )
+    .join("")
+
+  return table
+}
+
+export { toCellText } from "./utilities.js"
+export * from "./types.js"
diff --git a/src/types.ts b/src/types.ts
new file mode 100644
index 0000000..ad73987
--- /dev/null
+++ b/src/types.ts
@@ -0,0 +1,75 @@
+import type { alignmentOptions } from "./index.js"
+
+export interface LooseObject {
+  [key: string]: unknown
+}
+
+export type InputData<T = LooseObject> = T[]
+
+export type Alignment =
+  | keyof typeof alignmentOptions
+  | Uppercase<keyof typeof alignmentOptions>
+
+export interface ColumnDescriptor {
+  /**
+   * Alignment to use for this column.
+   */
+  align?: Alignment
+
+  /**
+   * Text to use as the column title.
+   */
+  name?: string
+}
+
+export type ToCellText = (value: unknown) => string
+
+export interface TablemarkOptions {
+  /**
+   * Whether to sentence-case header titles derived from input object
+   * keys.
+   */
+  caseHeaders?: boolean
+
+  /**
+   * Array for configuring column alignment, where each element sets
+   * options for its corresponding item in the input data.
+   *
+   * Each element can be either an object, in which case the `name`
+   * and `align` properties control the display of the column, or
+   * a `string` to be used as the column title.
+   */
+  columns?: Array<ColumnDescriptor | string>
+
+  /**
+   * Function used to convert input values to `string`s suitable
+   * for display in the output table. By default all values are
+   * converted using `String()` and `|` characters are escaped.
+   */
+  toCellText?: ToCellText
+
+  /**
+   * Whether to add `|` characters when wrapping within rows.
+   */
+  wrapWithGutters?: boolean
+
+  /**
+   * Width at which to wrap the content of columns. The default is
+   * `Infinity` meaning no wrapping will be performed.
+   */
+  wrapWidth?: number
+
+  /**
+   * Text to use as the line ending, `\n` by default.
+   */
+  lineEnding?: string
+}
+
+export type TablemarkOptionsNormalized = Omit<
+  {
+    [key in keyof TablemarkOptions]-?: TablemarkOptions[key]
+  },
+  "columns"
+> & {
+  columns: ColumnDescriptor[]
+}
diff --git a/src/utilities.ts b/src/utilities.ts
new file mode 100644
index 0000000..a5acf58
--- /dev/null
+++ b/src/utilities.ts
@@ -0,0 +1,198 @@
+import { sentenceCase } from "sentence-case"
+import split from "split-text-to-chunks"
+
+import { alignmentOptions } from "./index.js"
+
+import type {
+  Alignment,
+  InputData,
+  ToCellText,
+  TablemarkOptions,
+  TablemarkOptionsNormalized
+} from "./types.js"
+
+const columnsWidthMin = 5
+const pipeRegex = /\|/g
+
+const alignmentSet: Set<Uppercase<Alignment>> = new Set([
+  "LEFT",
+  "CENTER",
+  "RIGHT"
+])
+
+export const pad = (
+  alignment: Alignment,
+  width: number,
+  content: string
+): string => {
+  if (alignment == null || alignment === alignmentOptions.left) {
+    return content.padEnd(width)
+  }
+
+  if (alignment === alignmentOptions.right) {
+    return content.padStart(width)
+  }
+
+  // center alignment
+  const remainder = Math.max(0, (width - content.length) % 2)
+  const sides = Math.max(0, (width - content.length - remainder) / 2)
+
+  return " ".repeat(sides) + content + " ".repeat(sides + remainder)
+}
+
+export const toCellText: ToCellText = v => {
+  if (typeof v === "undefined") return ""
+  return String(v).replace(pipeRegex, "\\|")
+}
+
+export const line = (
+  columns: readonly string[],
+  config: TablemarkOptionsNormalized,
+  forceGutters = false
+): string => {
+  const gutters = forceGutters ? true : config.wrapWithGutters
+
+  return (
+    (gutters ? "| " : "  ") +
+    columns.join(gutters ? " | " : "   ") +
+    (gutters ? " |" : "  ") +
+    config.lineEnding
+  )
+}
+
+export const row = (
+  alignments: readonly Alignment[],
+  widths: readonly number[],
+  columns: readonly string[],
+  config: TablemarkOptionsNormalized
+): string => {
+  const width = columns.length
+  const values = new Array(width)
+  const first = new Array(width)
+  let height = 1
+
+  for (let h = 0; h < width; h++) {
+    const cells = (values[h] = split(columns[h], widths[h]))
+    if (cells.length > height) height = cells.length
+    first[h] = pad(alignments[h], widths[h], cells[0])
+  }
+
+  if (height === 1) {
+    return line(first, config, true)
+  }
+
+  const lines = new Array(height)
+  lines[0] = line(first, config, true)
+
+  for (let v = 1; v < height; v++) {
+    lines[v] = new Array(width)
+  }
+
+  for (let h = 0; h < width; h++) {
+    const cells = values[h]
+    let v = 1
+
+    for (; v < cells.length; v++) {
+      lines[v][h] = pad(alignments[h], widths[h], cells[v])
+    }
+
+    for (; v < height; v++) {
+      lines[v][h] = " ".repeat(widths[h])
+    }
+  }
+
+  for (let h = 1; h < height; h++) {
+    lines[h] = line(lines[h], config)
+  }
+
+  return lines.join("")
+}
+
+export const normalizeOptions = (
+  options: TablemarkOptions
+): TablemarkOptionsNormalized => {
+  const defaults: TablemarkOptionsNormalized = {
+    toCellText: toCellText,
+    caseHeaders: true,
+    columns: [],
+    lineEnding: "\n",
+    wrapWidth: Infinity,
+    wrapWithGutters: false
+  }
+
+  Object.assign(defaults, options)
+
+  defaults.columns =
+    options?.columns?.map(descriptor => {
+      if (typeof descriptor === "string") {
+        return { name: descriptor }
+      }
+
+      const align =
+        (descriptor.align?.toUpperCase() as Uppercase<Alignment>) ??
+        alignmentOptions.left
+
+      if (!alignmentSet.has(align)) {
+        throw new TypeError(`Unknown alignment, got ${descriptor.align}`)
+      }
+
+      return {
+        align,
+        name: descriptor.name
+      }
+    }) ?? []
+
+  return defaults
+}
+
+export const getColumnTitles = (
+  keys: readonly string[],
+  config: TablemarkOptionsNormalized
+): string[] => {
+  return keys.map((key, i) => {
+    if (Array.isArray(config.columns)) {
+      const customTitle = config.columns[i]?.name
+
+      if (customTitle != null) {
+        return customTitle
+      }
+    }
+
+    if (!config.caseHeaders) {
+      return key
+    }
+
+    return sentenceCase(key)
+  })
+}
+
+export const getColumnWidths = (
+  input: InputData,
+  keys: readonly string[],
+  titles: readonly string[],
+  config: TablemarkOptionsNormalized
+): number[] => {
+  return input.reduce(
+    (sizes, item) =>
+      keys.map((key, i) =>
+        Math.max(
+          split.width(config.toCellText(item[key]), config.wrapWidth),
+          sizes[i]
+        )
+      ),
+    titles.map(t => Math.max(columnsWidthMin, split.width(t, config.wrapWidth)))
+  )
+}
+
+export const getColumnAlignments = (
+  keys: readonly string[],
+  config: TablemarkOptionsNormalized
+): Alignment[] => {
+  return keys.map((_, i) => {
+    if (typeof config.columns[i]?.align === "string") {
+      return config.columns[i].align as Alignment
+    }
+
+    return alignmentOptions.left
+  })
+}
diff --git a/test.js b/test.js
deleted file mode 100644
index 00b4254..0000000
--- a/test.js
+++ /dev/null
@@ -1,56 +0,0 @@
-'use strict'
-
-const test = require('ava')
-
-const fn = require('./')
-const cases = require('./fixtures/inputs')
-
-test('outputs the expected markdown', t => {
-  const result = fn(cases.standard.input)
-  t.is(result, cases.standard.expected)
-})
-
-test('works when provided alignment options', t => {
-  const result = fn(cases.alignments.input, cases.alignments.options)
-  t.is(result, cases.alignments.expected)
-})
-
-test('replaces column names when provided', t => {
-  const result = fn(cases.columns.input, cases.columns.options)
-  t.is(result, cases.columns.expected)
-})
-
-test('can override sentence casing', t => {
-  const result = fn(cases.casing.input, cases.casing.options)
-  t.is(result, cases.casing.expected)
-})
-
-test('can use custom stringify function', t => {
-  const result = fn(cases.coerce.input, cases.coerce.options)
-  t.is(result, cases.coerce.expected)
-})
-
-test('text wrapping', t => {
-  const result = fn(cases.wrap.input, cases.wrap.options)
-  t.is(result, cases.wrap.expected)
-})
-
-test('newlines', t => {
-  const result = fn(cases.newlines.input, cases.newlines.options)
-  t.is(result, cases.newlines.expected)
-})
-
-test('text wrapping and newlines combined', t => {
-  const result = fn(cases.wrapAndNewlines.input, cases.wrapAndNewlines.options)
-  t.is(result, cases.wrapAndNewlines.expected)
-})
-
-test('gutters', t => {
-  const result = fn(cases.gutters.input, cases.gutters.options)
-  t.is(result, cases.gutters.expected)
-})
-
-test('pipes in content', t => {
-  const result = fn(cases.pipes.input, cases.pipes.options)
-  t.is(result, cases.pipes.expected)
-})
diff --git a/tests/.eslintrc.cjs b/tests/.eslintrc.cjs
new file mode 100644
index 0000000..2f8a6d4
--- /dev/null
+++ b/tests/.eslintrc.cjs
@@ -0,0 +1,15 @@
+"use strict"
+
+const { resolve } = require("path")
+
+module.exports = {
+  extends: [resolve(__dirname, "../.eslintrc.cjs")],
+  overrides: [
+    {
+      files: ["**/*.{ts,tsx}"],
+      parserOptions: {
+        project: resolve(__dirname, "tsconfig.json")
+      }
+    }
+  ]
+}
diff --git a/tests/cases.ts b/tests/cases.ts
new file mode 100644
index 0000000..0d451b6
--- /dev/null
+++ b/tests/cases.ts
@@ -0,0 +1,57 @@
+import test from "ava"
+
+import tablemark from "../dist/index.js"
+import cases from "./fixtures/inputs.js"
+
+test("outputs the expected markdown", t => {
+  const result = tablemark(cases.standard.input)
+  t.is(result, cases.standard.expected)
+})
+
+test("works when provided alignment options", t => {
+  const result = tablemark(cases.alignments.input, cases.alignments.options)
+  t.is(result, cases.alignments.expected)
+})
+
+test("replaces column names when provided", t => {
+  const result = tablemark(cases.columns.input, cases.columns.options)
+  t.is(result, cases.columns.expected)
+})
+
+test("can override sentence casing", t => {
+  const result = tablemark(cases.casing.input, cases.casing.options)
+  t.is(result, cases.casing.expected)
+})
+
+test("can use custom stringify function", t => {
+  const result = tablemark(cases.coerce.input, cases.coerce.options)
+  t.is(result, cases.coerce.expected)
+})
+
+test("text wrapping", t => {
+  const result = tablemark(cases.wrap.input, cases.wrap.options)
+  t.is(result, cases.wrap.expected)
+})
+
+test("newlines", t => {
+  const result = tablemark(cases.newlines.input, cases.newlines.options)
+  t.is(result, cases.newlines.expected)
+})
+
+test("text wrapping and newlines combined", t => {
+  const result = tablemark(
+    cases.wrapAndNewlines.input,
+    cases.wrapAndNewlines.options
+  )
+  t.is(result, cases.wrapAndNewlines.expected)
+})
+
+test("gutters", t => {
+  const result = tablemark(cases.gutters.input, cases.gutters.options)
+  t.is(result, cases.gutters.expected)
+})
+
+test("pipes in content", t => {
+  const result = tablemark(cases.pipes.input, cases.pipes.options)
+  t.is(result, cases.pipes.expected)
+})
diff --git a/tests/fixtures/inputs.ts b/tests/fixtures/inputs.ts
new file mode 100644
index 0000000..37bdde8
--- /dev/null
+++ b/tests/fixtures/inputs.ts
@@ -0,0 +1,202 @@
+import type { TablemarkOptions } from "../../src/types.js"
+
+const EOL = "\n"
+
+interface TestCase {
+  input: Array<{ [key: string]: unknown }>
+  expected: string
+  options?: TablemarkOptions
+}
+
+const testCases: Record<string, TestCase> = {
+  standard: {
+    input: [
+      {
+        name: "trilogy",
+        repo: "[citycide/trilogy](//github.com/citycide/trilogy)",
+        desc: "No-hassle SQLite with type-casting schema models and support for native & pure JS backends."
+      },
+      {
+        name: "strat",
+        repo: "[citycide/strat](//github.com/citycide/strat)",
+        desc: "Functional-ish JavaScript string formatting, with inspirations from Python."
+      },
+      {
+        name: "tablemark",
+        repo: "[citycide/tablemark](//github.com/citycide/tablemark)",
+        desc: "Generate markdown tables from JSON data."
+      }
+    ],
+    expected:
+      [
+        "| Name      | Repo                                                  | Desc                                                                                        |",
+        "| :-------- | :---------------------------------------------------- | :------------------------------------------------------------------------------------------ |",
+        "| trilogy   | [citycide/trilogy](//github.com/citycide/trilogy)     | No-hassle SQLite with type-casting schema models and support for native & pure JS backends. |",
+        "| strat     | [citycide/strat](//github.com/citycide/strat)         | Functional-ish JavaScript string formatting, with inspirations from Python.                 |",
+        "| tablemark | [citycide/tablemark](//github.com/citycide/tablemark) | Generate markdown tables from JSON data.                                                    |"
+      ].join(EOL) + EOL
+  },
+  alignments: {
+    input: [
+      { name: "Bob", age: 21, isCool: false },
+      { name: "Sarah", age: 22, isCool: true },
+      { name: "Lee", age: 23, isCool: true }
+    ],
+    options: {
+      columns: [{ align: "left" }, { align: "right" }, { align: "center" }]
+    },
+    expected:
+      [
+        "| Name  |   Age | Is cool |",
+        "| :---- | ----: | :-----: |",
+        "| Bob   |    21 |  false  |",
+        "| Sarah |    22 |  true   |",
+        "| Lee   |    23 |  true   |"
+      ].join(EOL) + EOL
+  },
+  columns: {
+    input: [
+      { name: "Bob", age: 21, isCool: false },
+      { name: "Sarah", age: 22, isCool: true },
+      { name: "Lee", age: 23, isCool: true }
+    ],
+    options: {
+      columns: [{ name: "word" }, { name: "number" }, { name: "boolean" }]
+    },
+    expected:
+      [
+        "| word  | number | boolean |",
+        "| :---- | :----- | :------ |",
+        "| Bob   | 21     | false   |",
+        "| Sarah | 22     | true    |",
+        "| Lee   | 23     | true    |"
+      ].join(EOL) + EOL
+  },
+  casing: {
+    input: [
+      { name: "Bob", age: 21, isCool: false },
+      { name: "Sarah", age: 22, isCool: true },
+      { name: "Lee", age: 23, isCool: true }
+    ],
+    options: {
+      caseHeaders: false
+    },
+    expected:
+      [
+        "| name  | age   | isCool |",
+        "| :---- | :---- | :----- |",
+        "| Bob   | 21    | false  |",
+        "| Sarah | 22    | true   |",
+        "| Lee   | 23    | true   |"
+      ].join(EOL) + EOL
+  },
+  coerce: {
+    input: [
+      { name: "Bob", age: 21, isCool: false },
+      { name: "Sarah", age: 22, isCool: true },
+      { name: "Lee", age: 23, isCool: true }
+    ],
+    options: {
+      toCellText(v) {
+        if (v === true) return "Yes"
+        if (v === false) return "No"
+        return String(v)
+      }
+    },
+    expected:
+      [
+        "| Name  | Age   | Is cool |",
+        "| :---- | :---- | :------ |",
+        "| Bob   | 21    | No      |",
+        "| Sarah | 22    | Yes     |",
+        "| Lee   | 23    | Yes     |"
+      ].join(EOL) + EOL
+  },
+  wrap: {
+    input: [
+      { name: "Benjamin", age: 21, isCool: false },
+      { name: "Sarah", age: 22, isCool: true },
+      { name: "Lee", age: 23, isCool: true }
+    ],
+    options: {
+      wrapWidth: 5
+    },
+    expected:
+      [
+        // headers wrap, soft wrap
+        "| Name  | Age   | Is    |",
+        "                  cool   ",
+        "| :---- | :---- | :---- |",
+        // hard wrap
+        "| Benja | 21    | false |",
+        "  min                    ",
+        // no wrap
+        "| Sarah | 22    | true  |",
+        "| Lee   | 23    | true  |"
+      ].join(EOL) + EOL
+  },
+  newlines: {
+    input: [
+      { name: "Benjamin\nor Ben", age: 21, isCool: false },
+      { name: "Sarah", age: 22, isCool: true },
+      { name: "Lee", age: 23, isCool: true }
+    ],
+    expected:
+      [
+        "| Name     | Age   | Is cool |",
+        "| :------- | :---- | :------ |",
+        "| Benjamin | 21    | false   |",
+        "  or Ben                      ",
+        "| Sarah    | 22    | true    |",
+        "| Lee      | 23    | true    |"
+      ].join(EOL) + EOL
+  },
+  wrapAndNewlines: {
+    input: [
+      { name: "Benjamin or\nBen", age: 21, isCool: false },
+      { name: "Sarah", age: 22, isCool: true },
+      { name: "Lee", age: 23, isCool: true }
+    ],
+    options: {
+      wrapWidth: 8
+    },
+    expected:
+      [
+        "| Name     | Age   | Is cool |",
+        "| :------- | :---- | :------ |",
+        "| Benjamin | 21    | false   |",
+        "  or                          ",
+        "  Ben                         ",
+        "| Sarah    | 22    | true    |",
+        "| Lee      | 23    | true    |"
+      ].join(EOL) + EOL
+  },
+  gutters: {
+    input: [
+      { name: "Benjamin", age: 21, isCool: false },
+      { name: "Sarah", age: 22, isCool: true },
+      { name: "Lee", age: 23, isCool: true }
+    ],
+    options: {
+      wrapWidth: 5,
+      wrapWithGutters: true
+    },
+    expected:
+      [
+        "| Name  | Age   | Is    |",
+        "|       |       | cool  |",
+        "| :---- | :---- | :---- |",
+        "| Benja | 21    | false |",
+        "| min   |       |       |",
+        "| Sarah | 22    | true  |",
+        "| Lee   | 23    | true  |"
+      ].join(EOL) + EOL
+  },
+  pipes: {
+    input: [{ content: "yes | no" }],
+    expected:
+      ["| Content   |", "| :-------- |", "| yes \\| no |"].join(EOL) + EOL
+  }
+}
+
+export default testCases
diff --git a/tests/tsconfig.json b/tests/tsconfig.json
new file mode 100644
index 0000000..f75e3db
--- /dev/null
+++ b/tests/tsconfig.json
@@ -0,0 +1,6 @@
+{
+  "extends": "../tsconfig.json",
+  "include": [
+    "."
+  ]
+}
diff --git a/tests/utilities.ts b/tests/utilities.ts
new file mode 100644
index 0000000..06e040e
--- /dev/null
+++ b/tests/utilities.ts
@@ -0,0 +1,27 @@
+import test from "ava"
+
+import { alignmentOptions } from "../dist/index.js"
+import * as utilites from "../dist/utilities.js"
+
+test("pad: left alignment", t => {
+  t.is(utilites.pad(alignmentOptions.left, 2, "foo"), "foo")
+  t.is(utilites.pad(alignmentOptions.left, 6, "foo"), "foo   ")
+})
+
+test("pad: right alignment", t => {
+  t.is(utilites.pad(alignmentOptions.right, 2, "foo"), "foo")
+  t.is(utilites.pad(alignmentOptions.right, 6, "foo"), "   foo")
+})
+
+test("pad: center alignment", t => {
+  t.is(utilites.pad(alignmentOptions.center, 2, "foo"), "foo")
+  t.is(utilites.pad(alignmentOptions.center, 6, "foo"), " foo  ")
+  t.is(utilites.pad(alignmentOptions.center, 7, "foo"), "  foo  ")
+  t.is(utilites.pad(alignmentOptions.center, 8, "hi"), "   hi   ")
+})
+
+test("toCellText: renders its argument as a string suitable for a table cell", t => {
+  t.is(utilites.toCellText(undefined), "")
+  t.is(utilites.toCellText(3), "3")
+  t.is(utilites.toCellText("|"), "\\|")
+})
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..bac1dce
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,14 @@
+{
+  "compilerOptions": {
+    "module": "es2020",
+    "target": "es2020",
+    "moduleResolution": "node",
+    "strict": true,
+    "declaration": true,
+    "outDir": "dist"
+  },
+  "include": [
+    "src",
+    "declarations.d.ts"
+  ]
+}