| Aspect | CoAP | MQTT |
|---|
| Full Name | Constrained Application Protocol | Message Queuing Telemetry Transport |
| Developed By | IETF (RFC 7252) | IBM |
| Protocol Type | Request/Response (REST-like) | Publish/Subscribe |
| Transport Layer | UDP | TCP (optionally WebSockets) |
| Architecture Model | Client/Server | Broker-based |
| Message Broker Required | No | Yes |
| Communication Pattern | Synchronous (GET, POST, PUT, DELETE) | Asynchronous messaging |
| Multicast Support | Yes | No |
| Push Notification | Yes (CoAP Observe) | Yes (via broker) |
| Reliability | Optional acknowledgments | Built-in QoS (levels 0, 1, 2) |
| Overhead | Very low (compact binary format) | Low (slightly higher due to TCP) |
| Latency | Lower (no connection setup due to UDP) | Higher (TCP handshake required) |
| Power Consumption | Lower | Moderate |
| Security Protocol | DTLS (Datagram Transport Layer Security) | TLS (Transport Layer Security) |
| Authentication Options | DTLS-based (certificates, pre-shared keys) | Username/password, certificates |
| Web Integration | Good (HTTP-like URI and methods, easy proxying) | Limited (not natively compatible with HTTP) |
| Proxy Support | Yes (CoAP-to-HTTP proxies available) | Limited |
| Suitable for | Constrained devices, lossy networks, multicast scenarios | Reliable delivery, cloud integration, publish/subscribe |