MQTT vs. HTTP: Choosing the Right Protocol for Your IoT Project
January 30, 2026
MQTT vs. HTTP: Choosing the Right Protocol for Your IoT Project
When designing an IoT system, one of the most fundamental decisions is choosing the right communication protocol. While HTTP is the backbone of the web, MQTT has emerged as the de facto standard for IoT. Understanding their core differences is key to building an efficient and scalable system.
Architectural Differences
The most significant difference lies in their communication models.
HTTP: Request-Response
HTTP operates on a client-server, request-response model. A client sends a request to a server, and the server sends back a response. This is a one-to-one, synchronous interaction.
MQTT: Publish-Subscribe
MQTT uses a publish-subscribe (pub-sub) model, which is asynchronous and brokered. Clients connect to a central MQTT broker and can either publish messages to a "topic" or subscribe to a topic to receive messages.
Key Comparison Points
| Feature | HTTP | MQTT | Winner for IoT |
|---|---|---|---|
| Model | Request-Response | Publish-Subscribe | MQTT |
| Overhead | High (text-based headers) | Very Low (2-byte fixed header) | MQTT |
| Connection | Stateless (new connection per request) | Stateful (persistent TCP connection) | MQTT |
| Reliability | Relies on TCP | Built-in QoS levels (0, 1, 2) | MQTT |
Overhead and Power Consumption
HTTP headers are verbose. A simple POST request can have hundreds of bytes of header data, even if the payload is just a few bytes. For battery-powered devices sending frequent updates, like an ESP32 sensor, this directly impacts battery life.
MQTT, with its 2-byte header and persistent connection, is vastly more efficient. A device can remain in a low-power state and only wake when it needs to send or receive data, a core principle of efficient IoT design.
When is HTTP a Good Choice for IoT?
Despite MQTT's advantages, HTTP still has its place:
- Device-to-Cloud Data Ingestion: For devices that send infrequent, large batches of data, the overhead of a single HTTP POST is negligible.
- Firewall Traversal: HTTP uses standard web ports (80, 443) that are almost always open.
- Requesting Data: When a device needs to pull a specific file, like firmware or configuration, a simple HTTP GET is a direct solution.
Conclusion: For real-time, event-driven communication with resource-constrained devices, MQTT is the clear winner. HTTP should be reserved for specific, non-real-time tasks.