diff --git a/.env-example b/.env-example
index 200b33a..b9b842f 100644
--- a/.env-example
+++ b/.env-example
@@ -1,3 +1,4 @@
+TITO_SECURITY_TOKEN=xxx
 TWITTER_STREAM_KEY=xxx
 TWITCH_STREAM_KEY=xxx
 YOUTUBE_STREAM_KEY=xxx
diff --git a/.github/ISSUE_TEMPLATE/meetup-checklist.md b/.github/ISSUE_TEMPLATE/meetup-checklist.md
index 34bb3e6..01a2243 100644
--- a/.github/ISSUE_TEMPLATE/meetup-checklist.md
+++ b/.github/ISSUE_TEMPLATE/meetup-checklist.md
@@ -14,6 +14,7 @@ assignees: ''
 - [ ] duplicate meetup survey and update speaker info (Google Docs)
 - [ ] send email via Tito to previous month's attendees with link to survey + link to tickets
 - [ ] update website with event json
+- [ ] update TITO_SECURITY_TOKEN on Begin to match ti.to event security token (go to ti.to event > Settings > Webhook endpoints to view)
   
 ## (3 weeks out)
 - [ ] confirm sponsor & update website
diff --git a/app/api/webhooks/tito.mjs b/app/api/webhooks/tito.mjs
index b2d9fd1..5d36660 100644
--- a/app/api/webhooks/tito.mjs
+++ b/app/api/webhooks/tito.mjs
@@ -1,3 +1,4 @@
+import crypto from 'crypto'
 //import { addToCustomerIO } from "../signup.mjs"
 
 /* TODO: this code block (addToCustomerIO) is copied from ../signup.mjs because (for some reason) importing this function
@@ -34,9 +35,27 @@ export async function addToCustomerIO(first_name, last_name, email_address) {
 
 // process webhook requests from Tito.io, the ticketing system for SeattleJS meetups. Add these users to our mailing list.
 export async function post(req) {
+  // Check for the presence of the signature header.
+  const signature = req.headers['tito-signature']
+  if (!signature || signature === '') {
+    return {
+      json: { ok: false, error: 'missing security signature header' },
+      statusCode: 401
+    }
+  }
+
+  // Create an HMAC with the payload body using our security token, and convert to base64.
+  const hmac = crypto.createHmac('sha256', process.env.TITO_SECURITY_TOKEN)
+  const digest = hmac.update(req.rawBody).digest('base64')
+
+  if (signature !== digest) {
+    return {
+      json: { ok: false, error: 'security signature does not match' },
+      statusCode: 401
+    }
+  }
+
   let { first_name, last_name, email } = req.body
-  //console.log(first_name, last_name, email)
   await addToCustomerIO(first_name, last_name, email)
-  //console.log(foo)
   return { json: { ok: true } }
 }