diff --git a/README.md b/README.md
index 311c3ac381..459fc02018 100644
--- a/README.md
+++ b/README.md
@@ -6,10 +6,11 @@
 
 ## Local development
 
-Requires Node.js (`node`), Python (`python3`), and Java (`java`). It is known to work in these environments but should work in others:
+Requires Node.js (`node`), Python (`python3`), and Java (`java`). It is known to work in these environments but should work in many others:
 
- - Windows 10, Python 3.11.7 (Microsoft Store), Node.js 20.10.0 (nodejs.org installer), Java 11 (Temurin-11.0.21+9)
  - Windows 10, Python 3.12.1 (Microsoft Store), Node.js 20.10.0 (nodejs.org installer), Java 11 (Temurin-11.0.21+9)
+ - macOS 14.2.1, Python 3.11.6 (Apple), Node.js 20.10.0 (installed manually), Java 21 (Temurin-21.0.1+12)
+ - Ubuntu 22.04, Python 3.10.12 (python3 package), Node.js 20.10.0 (installed manually), Java 11 (openjdk-11-jre package)
 
 Install dependencies:
 
@@ -17,7 +18,7 @@ Install dependencies:
 npm ci
 ```
 
-Open tests/vertical_playground.html in a browser for local testing. You don't need to rebuild compressed versions for most changes.
+Open tests/vertical_playground.html in a browser for development. You don't need to rebuild compressed versions for most changes. Open tests/vertical_playground_compressed.html instead to test if the compressed versions built properly.
 
 To re-build compressed versions, run: