diff --git a/bin/lts.js b/bin/lts.js
index 3752e8c..3cc9f5d 100644
--- a/bin/lts.js
+++ b/bin/lts.js
@@ -3,6 +3,9 @@
 const Path = require('path');
 const Bossy = require('bossy');
 const Lib = require('../lib');
+const { writeFileSync } = require('node:fs');
+const Svg2png = require('svg2png');
+
 const now = new Date();
 const oneYearFromNow = new Date();
 
@@ -102,13 +105,22 @@ const options = {
   data: require(args.data),
   queryStart: new Date(args.start),
   queryEnd: new Date(args.end),
-  html: args.html ? Path.resolve(args.html) : null,
-  svg: args.svg ? Path.resolve(args.svg) : null,
-  png: args.png ? Path.resolve(args.png) : null,
   animate: args.animate,
   excludeMain: args.excludeMain,
   projectName: args.projectName,
   currentDateMarker: args.currentDateMarker
 };
 
-Lib.create(options);
+const d3n = Lib.create(options);
+
+if (args.html) {
+  writeFileSync(Path.resolve(args.html), d3n.html());
+}
+
+if (args.svg) {
+  writeFileSync(Path.resolve(args.svg), d3n.svgString());
+}
+
+if (args.png) {
+  writeFileSync(Path.resolve(args.png), Svg2png.sync(Buffer.from(d3n.svgString())));
+}
diff --git a/lib/index.d.ts b/lib/index.d.ts
new file mode 100644
index 0000000..6bee342
--- /dev/null
+++ b/lib/index.d.ts
@@ -0,0 +1,59 @@
+import { JSDOM } from "d3-node";
+
+export interface VersionData {
+  /** Start date of the version */
+  start: string;
+  /** LTS start date */
+  lts?: string;
+  /** Maintenance start date */
+  maintenance?: string;
+  /** End of life date */
+  end: string;
+  /** Codename */
+  codename?: string;
+}
+
+export interface ScheduleData {
+  [version: string]: VersionData;
+}
+
+export interface Margin {
+  top: number;
+  right: number;
+  bottom: number;
+  left: number;
+}
+
+export interface CreateOptions {
+  /** The schedule data object with version keys */
+  data: ScheduleData;
+  /** Start date for the chart query range */
+  queryStart: Date;
+  /** End date for the chart query range */
+  queryEnd: Date;
+  /** Whether to animate the bars (default: false) */
+  animate?: boolean;
+  /** Whether to exclude the "Main" row (default: false) */
+  excludeMain?: boolean;
+  /** Project name to prefix version labels */
+  projectName: string;
+  /** Chart margins (default: { top: 30, right: 30, bottom: 30, left: 110 }) */
+  margin?: Margin;
+  /** Color for the current date marker line (e.g., 'red', '#ff0000') */
+  currentDateMarker?: string;
+}
+
+export interface D3NodeResult {
+  /** Get the SVG element */
+  svgString(): string;
+  /** Get the HTML string */
+  html(): string;
+}
+
+/**
+ * Creates an D3 chart representing the Node.js LTS schedule
+ *
+ * @param options - Configuration options for the chart
+ * @returns A D3Node instance
+ */
+export function create(options: CreateOptions): D3NodeResult;
diff --git a/lib/index.js b/lib/index.js
index ff99db3..fddb9a9 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,9 +1,12 @@
 'use strict';
-const Fs = require('fs');
 const D3 = require('d3');
 const D3Node = require('d3-node');
 
 const styles = `
+svg {
+  width: 100%;
+  height: auto;
+}
 .current {
   fill: #5fa04e;
 }
@@ -92,7 +95,7 @@ function parseInput (data, queryStart, queryEnd, excludeMain, projectName) {
 
 
 function create (options) {
-  const { queryStart, queryEnd, html, svg: svgFile, png, animate, excludeMain, projectName, margin: marginInput, currentDateMarker } = options;
+  const { queryStart, queryEnd, animate, excludeMain, projectName, margin: marginInput, currentDateMarker } = options;
   const data = parseInput(options.data, queryStart, queryEnd, excludeMain, projectName);
   const d3n = new D3Node({ svgStyles: styles, d3Module: D3 });
   const margin = marginInput || { top: 30, right: 30, bottom: 30, left: 110 };
@@ -113,6 +116,8 @@ function create (options) {
   const svg = d3n.createSVG()
                  .attr('width', width + margin.left + margin.right)
                  .attr('height', height + margin.top + margin.bottom)
+                 .attr('viewBox', `0 0 ${width + margin.left + margin.right} ${height + margin.top + margin.bottom}`)
+                 .attr('preserveAspectRatio', 'xMinYMin meet')
                  .append('g')
                  .attr('id', 'bar-container')
                  .attr('transform', `translate(${margin.left}, ${margin.top})`);
@@ -220,19 +225,7 @@ function create (options) {
        return +(calculateWidth(data) >= min);
      });
 
-  if (typeof html === 'string') {
-    Fs.writeFileSync(html, d3n.html());
-  }
-
-  if (typeof svgFile === 'string') {
-    Fs.writeFileSync(svgFile, d3n.svgString());
-  }
-
-  if (typeof png === 'string') {
-    const Svg2png = require('svg2png'); // Load this lazily.
-
-    Fs.writeFileSync(png, Svg2png.sync(Buffer.from(d3n.svgString())));
-  }
+  return d3n;
 }
 
 module.exports.create = create;
diff --git a/package.json b/package.json
index 7829b90..a4520c8 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "version": "2.0.0",
   "description": "Generate the Node.js LTS schedule",
   "main": "lib/index.js",
+  "types": "lib/index.d.ts",
   "homepage": "https://github.com/nodejs/lts-schedule",
   "repository": {
     "type": "git",