diff --git a/docz/docs/03-demos/09-cloud/03-gsheet.md b/docz/docs/03-demos/09-cloud/03-gsheet.md
index d6d6731..48afbb9 100644
--- a/docz/docs/03-demos/09-cloud/03-gsheet.md
+++ b/docz/docs/03-demos/09-cloud/03-gsheet.md
@@ -16,6 +16,14 @@ referenced API version will be available in the future.
 
 :::
 
+:::note
+
+This demo focuses on external data processing.  For Google Apps Script custom
+functions, [the "Google Sheets" extension demo](/docs/demos/extensions/gsheet)
+covers Apps Script integration.
+
+:::
+
 ## Initial Configuration
 
 Install the dependencies:
diff --git a/docz/docs/03-demos/10-extensions/04-gsheet.md b/docz/docs/03-demos/10-extensions/04-gsheet.md
new file mode 100644
index 0000000..cfaa69b
--- /dev/null
+++ b/docz/docs/03-demos/10-extensions/04-gsheet.md
@@ -0,0 +1,198 @@
+---
+title: Google Sheets
+pagination_prev: demos/cloud/index
+pagination_next: demos/bigdata/index
+---
+
+:::note
+
+This demo focuses on Google Apps Script custom functions.  For external data
+processing, [the "Google Sheets" cloud data demo](/docs/demos/cloud/gsheet)
+covers the API for NodeJS scripts
+
+:::
+
+The [Standalone scripts](/docs/getting-started/installation/standalone) can be
+uploaded into an Apps Script project.  Once uploaded, the `XLSX` variable is
+available to other scripts in the project.
+
+Google Sheets currently does not provide support for working with Apple Numbers
+files and some legacy file formats. SheetJS fills the gap.
+
+The [Complete Demo](#complete-demo) defines a `SHEETJS` function that fetches a
+remote file, parses the contents, and writes data to the sheet:
+
+![Screenshot of final result](pathname:///gsheet/udf.png)
+
+:::note
+
+This demo was last tested on 2023 April 17.
+
+:::
+
+## Integration Details
+
+### Adding the script
+
+The `clasp` command line tool can be used to upload the standalone script:
+
+```bash
+npx @google/clasp clone SCRIPT_ID
+curl -LO https://cdn.sheetjs.com/xlsx-latest/package/dist/xlsx.full.min.js
+npx @google/clasp push
+```
+
+Once uploaded, the script `xlsx.full.min.gs` will be added to the project.
+
+The [Complete Demo](#complete-demo) includes more detailed setup instructions.
+
+### Fetching data
+
+`UrlFetchApp.fetch` performs a network request and returns a `HTTPResponse`:
+
+```js
+const response = UrlFetchApp.fetch("https://sheetjs.com/pres.numbers");
+```
+
+`HTTPResponse#getContent` returns the file data as an array of *signed* bytes:
+
+```js
+const content = response.getContent();
+```
+
+The `"array"` type for `XLSX.read` expects an array of *unsigned* bytes.
+Fortunately, the content can be corrected with bitwise operations:
+
+```js
+for(var i = 0; i < content.length; ++i) content[i] &= 0xFF;
+const wb = XLSX.read(content, { type: "array" });
+```
+
+### Returning data
+
+`XLSX.utils.sheet_to_json` with the option `header: 1` returns arrays of arrays
+that play nice with Google Sheets:
+
+```js
+const first_worksheet = wb.Sheets[wb.SheetNames[0]];
+const aoa = XLSX.utils.sheet_to_json(first_worksheet, {header: 1});
+```
+
+## Complete Demo
+
+This demo creates a function `SHEETJS(url)` that fetches the specified URL,
+extracts data from the first worksheet, and writes the data
+
+### Initial Setup
+
+0) Sign into a Google account (or create a new one)
+
+1) In a terminal window, run
+
+```bash
+npx @google/clasp login
+```
+
+A browser window should direct to an account selection page. Select the account
+from the previous step. In the next page, there will be a title like
+
+> clasp – The Apps Script CLI wants to access your Google Account
+
+At the bottom of the screen, click "Allow".
+
+The terminal window should now state
+
+```
+Authorization successful.
+```
+
+### Creating a Sheet
+
+2) Sign into Google Sheets with the same account and create a new blank sheet
+
+3) Open up the apps script window (Extensions > Apps Script)
+
+4) Click the gear icon (Project Settings) and copy the Script ID
+
+### Cloning the Apps Script
+
+5) In the terminal window, create a new folder for your project:
+
+```bash
+mkdir SheetJSGAS
+cd SheetJSGAS
+```
+
+6) Clone the Apps Script project.  The official command is:
+
+```bash
+npx @google/clasp clone PASTE_YOUR_ID_HERE
+```
+
+Type `npx @google/clasp clone ` in the terminal with a trailing space (do not
+press Enter yet!), then copy the Script ID from the Apps Script settings page
+and paste in the terminal.  Press Enter after pasting the ID.
+
+### Adding the SheetJS Library
+
+7) Download the standalone build and move to the project directory:
+
+```bash
+curl -LO https://cdn.sheetjs.com/xlsx-latest/package/dist/xlsx.full.min.js
+```
+
+8) Push the project to Apps Script:
+
+```bash
+npx @google/clasp push
+```
+
+:::caution
+
+If the push command fails with an error message like
+
+> User has not enabled the Apps Script API
+
+The message includes a URL (`https://script.google.com/home/usersettings` when
+the demo was last tested). Visit that URL and enable the Google Apps Script API.
+After enabling the API, run `npx @google/clasp push` again.
+
+:::
+
+9) Reopen the Google Sheet and Apps Script editor (Extensions > Apps Script).
+
+In the Files listing, there should be a new entry `xlsx.full.min.gs`
+
+### Creating a Custom Function
+
+10) In Apps Script editor, select `Code.gs` and erase the code in the editor.
+Replace with the following function:
+
+```js title="Code.gs"
+function SHEETJS(url) {
+  /* fetch data */
+  const res = UrlFetchApp.fetch(url || "https://sheetjs.com/pres.numbers");
+  const content = res.getContent();
+
+  /* fix data */
+  for(var i = 0; i < content.length; ++i) content[i] &= 0xFF;
+
+  /* parse */
+  const wb = XLSX.read(content, {type: "array"});
+
+  /* generate array of arrays from worksheet */
+  const ws = wb.Sheets[wb.SheetNames[0]];
+  const aoa = XLSX.utils.sheet_to_json(ws, {header: 1});
+  return aoa;
+}
+```
+
+Click the "Save Project" icon to save the project.
+
+11) In the Google Sheets window, select cell A1 and enter the formula
+
+```
+=SHEETJS("https://sheetjs.com/pres.numbers")
+```
+
+The file will be fetched and the contents will be written to the sheet.
diff --git a/docz/static/gsheet/udf.png b/docz/static/gsheet/udf.png
new file mode 100644
index 0000000..d7149ef
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diff --git a/docz/version.js b/docz/version.js
index 592db19..64be04b 100644
--- a/docz/version.js
+++ b/docz/version.js
@@ -1,2 +1,2 @@
-const current = "0.19.2";
+const current = "0.19.3";
 export default current;