My dashboardSign in

Communication · Messaging

WhatsApp-style app

Illustrative system design for a messaging app like WhatsApp: 6 topics to read, from requirements to deep dives.

Two copies of the truth, kept honest.

Illustrative design, not WhatsApp’s actual implementation. Arrowbox is not affiliated with WhatsApp’s owner. Disclaimer

Start with Link a device Sign in to start readingUpdated 2 Oct 2026

Linked devices

  • Link a deviceAdvanced · 46 min read · Sign in to read

    QR pairing, rotating codes, first history sync and one active tab.

Chat

  • Chat listIntermediate · 45 min read · Sign in to read

    Live reordering, unread counts, pinned and archived chats, filter chips.

  • Chat threadIntermediate · 45 min read · Sign in to read

    Virtualised history, scroll anchoring, optimistic send.

  • Message delivery statesIntermediate · 46 min read · Sign in to read

    Sending, sent, delivered, read; failed and retry; group receipts.

Media

  • Photo and voice messagesIntermediate · 44 min read · Sign in to read

    Upload inside the bubble, voice note recording and playback.

  • Voice and video callsAdvanced · 44 min read · Sign in to read

    Device check, speaker grid, mute, screen share; reconnecting, not dropping.