diff --git a/.changeset/huge-zoos-start.md b/.changeset/huge-zoos-start.md
new file mode 100644
index 0000000..fcb1c7b
--- /dev/null
+++ b/.changeset/huge-zoos-start.md
@@ -0,0 +1,5 @@
+---
+"@nodesecure/sec-literal": minor
+---
+
+Remove un-maintained is-base64 package and re-implement the function in the sec-literal project with proper TS definition
diff --git a/workspaces/sec-literal/package.json b/workspaces/sec-literal/package.json
index aea9bb2..2ff39d9 100644
--- a/workspaces/sec-literal/package.json
+++ b/workspaces/sec-literal/package.json
@@ -33,11 +33,7 @@
   "homepage": "https://github.com/NodeSecure/js-x-ray/tree/master/workspaces/sec-literal#readme",
   "dependencies": {
     "frequency-set": "^2.1.0",
-    "is-base64": "^1.1.0",
     "is-svg": "^6.0.0",
     "string-width": "^8.0.0"
-  },
-  "devDependencies": {
-    "@types/is-base64": "^1.1.3"
   }
 }
diff --git a/workspaces/sec-literal/src/literal.ts b/workspaces/sec-literal/src/literal.ts
index 6e461b2..6e6e128 100644
--- a/workspaces/sec-literal/src/literal.ts
+++ b/workspaces/sec-literal/src/literal.ts
@@ -1,5 +1,5 @@
-// Import Third-party Dependencies
-import isStringBase64 from "is-base64";
+// Import Internal Dependencies
+import { isStringBase64 } from "./utils.js";
 
 export type ESTreeLiteral = {
   type: "Literal";
diff --git a/workspaces/sec-literal/src/utils.ts b/workspaces/sec-literal/src/utils.ts
index 4979c4c..2d89842 100644
--- a/workspaces/sec-literal/src/utils.ts
+++ b/workspaces/sec-literal/src/utils.ts
@@ -5,6 +5,38 @@ import stringWidth from "string-width";
 // Import Internal Dependencies
 import { toValue, type ESTreeLiteral } from "./literal.js";
 
+export interface IsBase64Options {
+  allowMime?: boolean;
+  mimeRequired?: boolean;
+  paddingRequired?: boolean;
+  allowEmpty?: boolean;
+}
+
+export function isStringBase64(
+  v: string,
+  opts: IsBase64Options = {}
+): boolean {
+  if (opts.allowEmpty === false && v === "") {
+    return false;
+  }
+
+  let regex = "(?:[A-Za-z0-9+\\/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+\\/]{3}=)?";
+  const mimeRegex = "(data:\\w+\\/[a-zA-Z\\+\\-\\.]+;base64,)";
+
+  if (opts.mimeRequired === true) {
+    regex = mimeRegex + regex;
+  }
+  else if (opts.allowMime === true) {
+    regex = mimeRegex + "?" + regex;
+  }
+
+  if (opts.paddingRequired === false) {
+    regex = "(?:[A-Za-z0-9+\\/]{4})*(?:[A-Za-z0-9+\\/]{2}(==)?|[A-Za-z0-9+\\/]{3}=?)?";
+  }
+
+  return (new RegExp("^" + regex + "$", "gi")).test(v);
+}
+
 export function isSvg(
   strOrLiteral: ESTreeLiteral | string
 ): boolean {
diff --git a/workspaces/sec-literal/test/isStringBase64.spec.ts b/workspaces/sec-literal/test/isStringBase64.spec.ts
new file mode 100644
index 0000000..cd0122d
--- /dev/null
+++ b/workspaces/sec-literal/test/isStringBase64.spec.ts
@@ -0,0 +1,50 @@
+/* eslint-disable @stylistic/max-len */
+// Import Node.js Dependencies
+import { test } from "node:test";
+import assert from "node:assert/strict";
+
+// Import Internal Dependencies
+import { isStringBase64 } from "../src/utils.js";
+
+test("isBase64", function isBase64() {
+  const pngString = "iVBORw0KGgoAAAANSUhEUgAABQAAAALQAQMAAAD1s08VAAAAA1BMVEX/AAAZ4gk3AAAAh0lEQVR42u3BMQEAAADCoPVPbQlPoAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAB4GsTfAAGc95RKAAAAAElFTkSuQmCC";
+  const pngStringWithMime = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABQAAAALQAQMAAAD1s08VAAAAA1BMVEX/AAAZ4gk3AAAAh0lEQVR42u3BMQEAAADCoPVPbQlPoAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAB4GsTfAAGc95RKAAAAAElFTkSuQmCC";
+  const jpgString = "/9j/4AAQSkZJRgABAQAAAQABAAD/2wCEACAhITMkM1EwMFFCLy8vQiccHBwcJyIXFxcXFyIRDAwMDAwMEQwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwBIjMzNCY0IhgYIhQODg4UFA4ODg4UEQwMDAwMEREMDAwMDAwRDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDP/AABEIAAYABgMBIgACEQEDEQH/xABVAAEBAAAAAAAAAAAAAAAAAAAAAxAAAQQCAwEAAAAAAAAAAAAAAgABAxQEIxIkMxMBAQAAAAAAAAAAAAAAAAAAAAARAQAAAAAAAAAAAAAAAAAAAAD/2gAMAwEAAhEDEQA/AIE7MwkbOUJDJWx+ZjXATitx2/h2bEWvX5Y0npQ7aIiD/9k=";
+  const jpgStringWithMime = "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wCEACAhITMkM1EwMFFCLy8vQiccHBwcJyIXFxcXFyIRDAwMDAwMEQwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwBIjMzNCY0IhgYIhQODg4UFA4ODg4UEQwMDAwMEREMDAwMDAwRDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDP/AABEIAAYABgMBIgACEQEDEQH/xABVAAEBAAAAAAAAAAAAAAAAAAAAAxAAAQQCAwEAAAAAAAAAAAAAAgABAxQEIxIkMxMBAQAAAAAAAAAAAAAAAAAAAAARAQAAAAAAAAAAAAAAAAAAAAD/2gAMAwEAAhEDEQA/AIE7MwkbOUJDJWx+ZjXATitx2/h2bEWvX5Y0npQ7aIiD/9k=";
+
+  // Test agains real images
+  assert.equal(isStringBase64(pngString), true);
+  assert.equal(isStringBase64(pngStringWithMime), false);
+  assert.equal(isStringBase64(pngStringWithMime, { allowMime: true }), true);
+  assert.equal(isStringBase64(pngString, { mimeRequired: true }), false);
+  assert.equal(isStringBase64(pngStringWithMime, { mimeRequired: true }), true);
+  assert.equal(isStringBase64(jpgString), true);
+  assert.equal(isStringBase64(jpgStringWithMime), false);
+  assert.equal(isStringBase64(jpgStringWithMime, { allowMime: true }), true);
+
+  // helper for creating fake valid mime strings
+  function createMimeString(mime: string): string {
+    return `data:${mime};base64,${pngString}`;
+  }
+
+  // Random complex mime types taken from:
+  // http://www.freeformatter.com/mime-types-list.html
+  assert.equal(isStringBase64(createMimeString("application/vnd.apple.installer+xml"), { allowMime: true }), true);
+  assert.equal(isStringBase64(createMimeString("image/svg+xml"), { allowMime: true }), true);
+  assert.equal(isStringBase64(createMimeString("application/set-payment-initiation"), { allowMime: true }), true);
+  assert.equal(isStringBase64(createMimeString("image/vnd.adobe.photoshop"), { allowMime: true }), true);
+
+  assert.equal(isStringBase64("1342234"), false);
+  assert.equal(isStringBase64("afQ$%rfew"), false);
+  assert.equal(isStringBase64("dfasdfr342"), false);
+  assert.equal(isStringBase64("uuLMhh"), false);
+  assert.equal(isStringBase64("uuLMhh", { paddingRequired: false }), true);
+  assert.equal(isStringBase64("uuLMhh", { paddingRequired: true }), false);
+  assert.equal(isStringBase64("uuLMhh=="), true);
+  assert.equal(isStringBase64("uuLMhh==", { paddingRequired: false }), true);
+  assert.equal(isStringBase64("uuLMhh==", { paddingRequired: true }), true);
+  assert.equal(isStringBase64("data:image/png;base64,uuLMhh==", { paddingRequired: true }), false);
+  assert.equal(isStringBase64("data:image/png;base64,uuLMhh==", { paddingRequired: true, allowMime: true }), true);
+  assert.equal(isStringBase64(""), true);
+  assert.equal(isStringBase64("", { allowEmpty: false }), false);
+});