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MQTT and AMQP are messaging protocols; RabbitMQ, Kafka, NATS, and Apache Pulsar are software systems. They are not six equivalent products. Choose by the message pattern you need, whether consumers must replay retained data, which protocol or client your applications require, and what you can operate reliably.
Protocol or platform: what are you comparing?
A protocol defines how messaging participants communicate. A broker or platform implements a system around messaging, with behaviors such as routing, storage, acknowledgements, and operations. A broker can support more than one protocol, so protocol support alone does not make two brokers interchangeable.
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This distinction matters especially for AMQP. AMQP 1.0 and AMQP 0-9-1 are different protocol versions, not interchangeable names for one wire protocol. RabbitMQ documents support for both, as well as several other protocols. For a connection or migration, check the exact version required by the client and supported by the broker.
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| Option | What it is | Documented center of the model | Start here if… |
|---|---|---|---|
| MQTT 5.0 | Client-server publish/subscribe transport protocol | Lightweight messaging, including constrained environments and bandwidth-limited IoT or machine-to-machine use cases; has three quality-of-service levels. | Devices or applications need a lightweight publish/subscribe protocol and their client and broker support the required MQTT behavior. |
| AMQP 1.0 | Open protocol for business messaging | Standardized wire-level messaging, with a layered architecture covering encoding, transport, message format, transactions, and security. | Interoperability with an AMQP 1.0-speaking system is a requirement. |
| RabbitMQ 4.3 | Multi-protocol broker | Broker-based messaging; its documentation lists AMQP 1.0, AMQP 0-9-1, MQTT, STOMP, and RabbitMQ Stream Protocol support. | You need a broker and want to compare its specific protocol and messaging capabilities with alternatives. |
| Apache Kafka | Event-streaming platform | Events organized in topics, producers and consumers, durable storage for later retrieval, and APIs for stream processing. | Events need to be retained and consumed or processed by multiple downstream applications. |
| NATS | Messaging system with distinct Core NATS and JetStream concepts | The official documentation separates Core NATS from JetStream; determine which model you mean before comparing persistence or replay behavior. | Your decision depends on whether Core NATS or JetStream meets the behavior your application requires. |
| Apache Pulsar 5.0.x | Pub-sub messaging system | Producers publish to topics; consumers subscribe, process, and acknowledge. Documentation describes retention while a consumer is disconnected and redelivery after failed processing. | Disconnected consumers, acknowledgements, and retained messages are part of the use case you need to assess. |
The table describes documented models, not a complete feature matrix. Actual delivery, retention, routing, and ordering depend on the implementation, configuration, and application design.
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What each option means in practice
MQTT: a lightweight transport with selectable QoS
The OASIS MQTT Version 5.0 specification describes MQTT as a client-server publish/subscribe messaging transport protocol. It is designed to be lightweight and identifies constrained environments, including IoT and machine-to-machine communication, as use cases. Its three quality-of-service levels let participants select different protocol delivery behavior.
Choose the QoS level deliberately, but do not treat protocol delivery as proof that an application completed its work. For example, receiving a message at the protocol level does not by itself establish that a downstream database update or other side effect happened exactly once. Define what “complete” means in the application and handle retries or duplicates accordingly.
AMQP: a standard whose version must be explicit
The OASIS AMQP Version 1.0, Part 0: Overview calls AMQP an open internet protocol for business messaging. AMQP 1.0 defines a layered architecture that includes type system and encoding, transport, message format, transactions, and security. Its stated aim is interoperability among conformant implementations without requiring extensions outside the specification.
That does not make every product labelled “AMQP” compatible with every other one. Specify AMQP 1.0 or AMQP 0-9-1 when selecting a client, broker, or migration path. RabbitMQ’s support for both is product support for distinct protocol versions, not evidence that the versions are the same.
RabbitMQ: compare the broker’s actual capabilities
RabbitMQ is a broker, not a protocol. Its version 4.3 comparison documentation lists support for AMQP 1.0, AMQP 0-9-1, MQTT, STOMP, and RabbitMQ Stream Protocol. If several applications already use different protocols, that inventory may be relevant—but confirm the required protocol version and feature behavior for each client.
RabbitMQ’s vendor-authored comparison page describes an older division in which RabbitMQ was associated with messaging and task queueing and Kafka with event streaming, then notes that their capabilities have increasingly overlapped. Treat that as a reason to compare concrete requirements, not as an independent verdict or a timeless queue-versus-stream rule.
Kafka: durable event streams and downstream processing
Apache Kafka describes itself as an event-streaming platform. Its documentation centers on events organized in topics, producers that write them, consumers that read them, durable storage for later retrieval, and APIs for stream processing. This model is useful to assess when multiple downstream applications need to consume or process retained events without being tightly coupled to the producer.
Retention, ordering, delivery outcomes, and processing guarantees are not automatic consequences of choosing Kafka. They depend on configuration and application design. Specify how long events must remain available, which consumers need them, and what should happen when processing fails.
NATS: decide whether Core NATS or JetStream is in scope
NATS documentation organizes its concepts and architecture material into Core NATS and JetStream areas. The distinction is important: a comparison that says only “NATS” may leave unclear which behavior is being evaluated. State whether the use case needs the model documented under Core NATS or JetStream before making claims about persistence or replay.
The available NATS documentation cited here does not establish a complete six-system feature matrix or a cross-product performance ranking. Evaluate the specific NATS mode and configuration against the same requirements you use for the other candidates.
Apache Pulsar: pub-sub with acknowledgements and retention behavior
Apache Pulsar’s 5.0.x messaging concepts describe producers publishing messages to topics and consumers subscribing, processing, and acknowledging them. The documentation also describes messages being retained while a consumer is disconnected and redelivery after failed processing.
Those behaviors are useful comparison points, not unconditional guarantees for every deployment. Check the subscription and system configuration for the retention and delivery behavior your application needs, and define how it handles redelivery.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How should you choose?
- Start with the message pattern. Identify whether you are moving device telemetry, business messages, tasks, event streams, or broader pub-sub traffic. Do not choose from product names alone.
- Make interoperability a hard requirement where necessary. Record the protocol and version each producer and consumer can speak, available client libraries, and any broker-side protocol support you depend on. For AMQP, write down the version explicitly.
- Define completion and failure behavior. Specify what counts as delivered, processed, and complete; whether acknowledgements or retries are needed; how duplicates are handled; and whether ordering matters. A transport acknowledgement is not the same as an exactly-once application side effect.
- Decide whether consumers need history. Ask whether a consumer may disconnect and later process retained messages, whether new consumers need earlier events, and how retention should be configured. Kafka and Pulsar documentation make durable or retained messages part of their described models; verify actual settings for the deployment you are considering.
- Map routing and fan-out. Identify how subscribers receive the messages they need and where filtering or routing occurs—in the broker, topics or streams, or application logic. The available documentation does not support a complete routing feature comparison across all six choices, so verify the specific behavior required.
- Include the operating model. Account for deployment topology, scaling, monitoring, upgrades, security, backup, and the team’s operational experience. These are deployment-specific; do not assume one system is easier or cheaper without the context and evidence to support that claim.
How should you compare performance?
The official materials described here explain product and protocol models, but do not provide a neutral, apples-to-apples benchmark across MQTT, AMQP, RabbitMQ, Kafka, NATS, and Pulsar. There is no supported universal winner for throughput, latency, or cost in this comparison.
Benchmark the candidate configuration against representative traffic. Keep the workload and success criteria consistent, and vary the factors that reflect production:
- Payload sizes and message rates.
- Producer and consumer counts, including the fan-out pattern.
- Durability, acknowledgement, and retention settings.
- Consumer lag, reconnects, retries, and failure recovery.
- Latency and throughput under normal load and during the failure cases that matter to the application.
Record the exact product version, configuration, deployment environment, and client behavior for each test. A result from one workload does not establish a general ranking.
What should you verify before committing?
For a self-managed deployment or a provider-operated service, compare the specific offer rather than assuming the underlying product name tells the whole story. Confirm supported protocols and versions, client compatibility, retention and delivery behavior, deployment geography, operational responsibilities, and migration requirements. Provider availability and data residency are not established by the protocol and project documentation described here.
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