Keep Alive

Why do Heroku dynos sleep?

Free tier Heroku dynos automatically sleep after 30 minutes of inactivity. They also sleep 6 hours in any 24-hour period regardless of traffic (as of Heroku's policy changes).

What happens when a dyno sleeps?

When a sleeping dyno receives traffic, Heroku must wake it up - taking 10-30 seconds. During this time, users see a loading screen or timeout.

How does Keep Alive prevent Heroku dyno sleep?

Keep Alive sends HTTP requests to your Heroku app before the 30-minute inactivity timeout is reached:

• Configurable ping intervals (25 minutes recommended for Heroku)
• Works with any Heroku stack/language
• No code changes required
• Dashboard shows uptime statistics

Setup guide

1. Add your Heroku app URL to Keep Alive
2. Set ping interval to 25 minutes
3. Optionally create a lightweight health endpoint
4. Monitor response times to verify dyno remains awake

Important Heroku limitations

The 6-hour sleep quota per 24 hours on free tier cannot be circumvented by pinging. For production apps requiring 24/7 uptime, consider Heroku's Eco or Basic plans. Keep Alive will still optimize uptime within free tier constraints.

Best practices for Heroku apps

• Strategic pinging: If you have usage patterns, time your pings during likely user hours
• Quick startup: Optimize your app's boot time for faster recovery from sleep
• Multiple dynos: For complex apps, ping each service separately
• Database connections: Use connection pooling to handle reconnects after sleep

Heroku-specific tips

Beyond basic pinging, these strategies can help with Heroku free tier:

• Worker dynos: Use separate worker dynos for background tasks (they have different sleep policies)
• Memory leaks: Heroku's R14 errors are more common on free dynos - fix memory leaks
• Startup hooks: Implement proper startup hooks to handle post-sleep initialization
• Timeout handling: Implement progressive timeout handling in your app

Heroku vs other platforms