diff --git a/packages/mermaid/package.json b/packages/mermaid/package.json
index f7b54eba9..f411d811f 100644
--- a/packages/mermaid/package.json
+++ b/packages/mermaid/package.json
@@ -36,7 +36,7 @@
     "docs:verify": "pnpm docs:code && ts-node-esm src/docs.mts --verify",
     "docs:pre:vitepress": "rimraf src/vitepress && pnpm docs:code && ts-node-esm src/docs.mts --vitepress",
     "docs:build:vitepress": "pnpm docs:pre:vitepress && vitepress build src/vitepress",
-    "docs:dev": "pnpm docs:pre:vitepress && vitepress dev src/vitepress",
+    "docs:dev": "pnpm docs:pre:vitepress && concurrently \"vitepress dev src/vitepress\" \"ts-node-esm src/docs.mts --watch --vitepress\"",
     "docs:serve": "pnpm docs:build:vitepress && vitepress serve src/vitepress",
     "release": "pnpm build",
     "lint": "eslint --cache --ignore-path .gitignore . && pnpm lint:jison && prettier --check .",
@@ -88,10 +88,12 @@
     "@types/express": "4.17.14",
     "@types/jsdom": "20.0.0",
     "@types/lodash": "4.14.186",
+    "@types/micromatch": "^4.0.2",
     "@types/prettier": "2.7.1",
     "@types/stylis": "4.0.2",
     "@typescript-eslint/eslint-plugin": "5.41.0",
     "@typescript-eslint/parser": "5.41.0",
+    "chokidar": "^3.5.3",
     "concurrently": "7.5.0",
     "coveralls": "3.1.1",
     "cypress": "10.11.0",
@@ -114,6 +116,7 @@
     "js-base64": "3.7.2",
     "jsdom": "20.0.2",
     "lint-staged": "13.0.3",
+    "micromatch": "^4.0.5",
     "moment": "2.29.4",
     "path-browserify": "1.0.1",
     "prettier": "2.7.1",
@@ -138,4 +141,4 @@
     "**/*.css",
     "**/*.scss"
   ]
-}
+}
\ No newline at end of file
diff --git a/packages/mermaid/src/docs.mts b/packages/mermaid/src/docs.mts
index 96f5e9024..f44400a1b 100644
--- a/packages/mermaid/src/docs.mts
+++ b/packages/mermaid/src/docs.mts
@@ -30,7 +30,7 @@
  * @todo Write a test file for this. (Will need to be able to deal .mts file. Jest has trouble with
  *   it.)
  */
-import { readFileSync, writeFileSync, mkdirSync, existsSync } from 'fs';
+import { readFileSync, writeFileSync, mkdirSync, existsSync, rmSync, rmdirSync } from 'fs';
 import { exec } from 'child_process';
 import { globby } from 'globby';
 import { JSDOM } from 'jsdom';
@@ -38,6 +38,8 @@ import type { Code, Root } from 'mdast';
 import { posix, dirname, relative } from 'path';
 import prettier from 'prettier';
 import { remark } from 'remark';
+import chokidar from 'chokidar';
+import mm from 'micromatch';
 // @ts-ignore No typescript declaration file
 import flatmap from 'unist-util-flatmap';
 
@@ -47,6 +49,7 @@ const MERMAID_MAJOR_VERSION = (
 
 const verifyOnly: boolean = process.argv.includes('--verify');
 const git: boolean = process.argv.includes('--git');
+const watch: boolean = process.argv.includes('--watch');
 const vitepress: boolean = process.argv.includes('--vitepress');
 const noHeader: boolean = process.argv.includes('--noHeader') || vitepress;
 
@@ -246,11 +249,15 @@ const transformHtml = (filename: string) => {
   copyTransformedContents(filename, !verifyOnly, formattedHTML);
 };
 
-const getFilesFromGlobs = async (globs: string[]): Promise<string[]> => {
+const getGlobs = (globs: string[]): string[] => {
   globs.push('!**/dist');
   if (!vitepress) {
     globs.push('!**/.vitepress', '!**/vite.config.ts', '!src/docs/index.md');
   }
+  return globs;
+};
+
+const getFilesFromGlobs = async (globs: string[]): Promise<string[]> => {
   return await globby(globs, { dot: true });
 };
 
@@ -263,15 +270,18 @@ const getFilesFromGlobs = async (globs: string[]): Promise<string[]> => {
   const sourceDirGlob = posix.join('.', SOURCE_DOCS_DIR, '**');
   const action = verifyOnly ? 'Verifying' : 'Transforming';
 
-  const mdFiles = await getFilesFromGlobs([posix.join(sourceDirGlob, '*.md')]);
+  const mdFileGlobs = getGlobs([posix.join(sourceDirGlob, '*.md')]);
+  const mdFiles = await getFilesFromGlobs(mdFileGlobs);
   console.log(`${action} ${mdFiles.length} markdown files...`);
   mdFiles.forEach(transformMarkdown);
 
-  const htmlFiles = await getFilesFromGlobs([posix.join(sourceDirGlob, '*.html')]);
+  const htmlFileGlobs = getGlobs([posix.join(sourceDirGlob, '*.html')]);
+  const htmlFiles = await getFilesFromGlobs(htmlFileGlobs);
   console.log(`${action} ${htmlFiles.length} html files...`);
   htmlFiles.forEach(transformHtml);
 
-  const otherFiles = await getFilesFromGlobs([sourceDirGlob, '!**/*.md', '!**/*.html']);
+  const otherFileGlobs = getGlobs([sourceDirGlob, '!**/*.md', '!**/*.html']);
+  const otherFiles = await getFilesFromGlobs(otherFileGlobs);
   console.log(`${action} ${otherFiles.length} other files...`);
   otherFiles.forEach((file: string) => {
     copyTransformedContents(file, !verifyOnly); // no transformation
@@ -287,4 +297,32 @@ const getFilesFromGlobs = async (globs: string[]): Promise<string[]> => {
       exec(`git add ${FINAL_DOCS_DIR}`);
     }
   }
+
+  if (watch) {
+    console.log(`Watching for changes in ${SOURCE_DOCS_DIR}`);
+
+    const matcher = (globs: string[]) => (file: string) => mm.every(file, globs);
+    const isMd = matcher(mdFileGlobs);
+    const isHtml = matcher(htmlFileGlobs);
+    const isOther = matcher(otherFileGlobs);
+
+    chokidar
+      .watch(SOURCE_DOCS_DIR)
+      // Delete files from the final docs dir if they are deleted from the source dir
+      .on('unlink', (file: string) => rmSync(changeToFinalDocDir(file)))
+      .on('unlinkDir', (file: string) => rmdirSync(changeToFinalDocDir(file)))
+      .on('all', (event, path) => {
+        // Ignore other events.
+        if (!['add', 'change'].includes(event)) {
+          return;
+        }
+        if (isMd(path)) {
+          transformMarkdown(path);
+        } else if (isHtml(path)) {
+          transformHtml(path);
+        } else if (isOther(path)) {
+          copyTransformedContents(path, true);
+        }
+      });
+  }
 })();
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 3b11d52da..8290fdc4e 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -166,10 +166,12 @@ importers:
       '@types/express': 4.17.14
       '@types/jsdom': 20.0.0
       '@types/lodash': 4.14.186
+      '@types/micromatch': ^4.0.2
       '@types/prettier': 2.7.1
       '@types/stylis': 4.0.2
       '@typescript-eslint/eslint-plugin': 5.41.0
       '@typescript-eslint/parser': 5.41.0
+      chokidar: ^3.5.3
       concurrently: 7.5.0
       coveralls: 3.1.1
       cypress: 10.11.0
@@ -200,6 +202,7 @@ importers:
       khroma: ^2.0.0
       lint-staged: 13.0.3
       lodash: ^4.17.21
+      micromatch: ^4.0.5
       moment: 2.29.4
       moment-mini: ^2.24.0
       non-layered-tidy-tree-layout: ^2.0.2
@@ -239,10 +242,12 @@ importers:
       '@types/express': 4.17.14
       '@types/jsdom': 20.0.0
       '@types/lodash': 4.14.186
+      '@types/micromatch': 4.0.2
       '@types/prettier': 2.7.1
       '@types/stylis': 4.0.2
       '@typescript-eslint/eslint-plugin': 5.41.0_huremdigmcnkianavgfk3x6iou
       '@typescript-eslint/parser': 5.41.0_wyqvi574yv7oiwfeinomdzmc3m
+      chokidar: 3.5.3
       concurrently: 7.5.0
       coveralls: 3.1.1
       cypress: 10.11.0
@@ -265,6 +270,7 @@ importers:
       js-base64: 3.7.2
       jsdom: 20.0.2
       lint-staged: 13.0.3
+      micromatch: 4.0.5
       moment: 2.29.4
       path-browserify: 1.0.1
       prettier: 2.7.1
@@ -2302,6 +2308,10 @@ packages:
       '@types/node': 18.11.8
     dev: true
 
+  /@types/braces/3.0.1:
+    resolution: {integrity: sha512-+euflG6ygo4bn0JHtn4pYqcXwRtLvElQ7/nnjDu7iYG56H0+OhCd7d6Ug0IE3WcFpZozBKW2+80FUbv5QGk5AQ==}
+    dev: true
+
   /@types/cacheable-request/6.0.2:
     resolution: {integrity: sha512-B3xVo+dlKM6nnKTcmm5ZtY/OL8bOAOd2Olee9M1zft65ox50OzjEHW91sDiU9j6cvW8Ejg1/Qkf4xd2kugApUA==}
     dependencies:
@@ -2616,6 +2626,12 @@ packages:
       '@types/unist': 2.0.6
     dev: true
 
+  /@types/micromatch/4.0.2:
+    resolution: {integrity: sha512-oqXqVb0ci19GtH0vOA/U2TmHTcRY9kuZl4mqUxe0QmJAlIW13kzhuK5pi1i9+ngav8FjpSb9FVS/GE00GLX1VA==}
+    dependencies:
+      '@types/braces': 3.0.1
+    dev: true
+
   /@types/mime/3.0.1:
     resolution: {integrity: sha512-Y4XFY5VJAuw0FgAqPNd6NNoV44jbq9Bz2L7Rh/J6jLTiHBSBJa9fxqQIvkIld4GsoDOcCbvzOUAbLPsSKKg+uA==}
     dev: true