How to Design a Tweet Scheduler System (That Scales to Millions)

The Backend Behind Scheduled Tweets

Scheduling tweets might sound like a simple feature — but designing a system that can reliably post millions of tweets at the exact scheduled minute (or second) is anything but.
In this article, we’ll break down how to architect a scalable, distributed Tweet Scheduler system that handles high throughput and ensures reliability.

The same principles apply to scheduling systems across other domains — newsletters, SMS, emails, or even push notifications.

Functional Requirements

1. User can schedule a tweet for a future time (down to the minute or second).
2. Tweet is automatically posted at the scheduled time.
3. User can view, edit, or delete scheduled tweets.
4. Supports authentication and authorization (via Twitter OAuth).
5. Should reliably retry in case posting fails.
6. Users can schedule:

• Single tweets
• Threads (multi-tweet posts)
• Media attachments (images, videos)

7. Real-time status tracking of scheduled tweets (e.g., success, failed, pending).