Solace PubSub+ Event Broker

Solace PubSub+ Event Broker is a hybrid messaging platform for moving events among applications, AI agents, and devices across cloud, data-center, and edge environments. It is best suited to enterprises connecting distributed systems that must communicate through several protocols and deployment models. The combination is powerful for cross-environment integration, but paid capacity requires a careful workload fit and custom pricing.

Overview

Founded in 2001 and headquartered in Ottawa, Solace positions PubSub+ for demanding messaging and streaming deployments linking applications, customers, partners, and devices. Its event brokers can form an event mesh, routing information across clouds, data centers, and geographies. That architecture is valuable when systems are spread across locations or providers; a smaller installation contained within one environment may not need the additional routing layer.

The product is offered as a cloud service, software, or appliance. It can run in public clouds, data centers, and remote locations, making it a practical choice for hybrid estates with uneven connectivity or deployment requirements.

Key features

PubSub+ supports exchange patterns and quality-of-service choices, along with caching, partitioned queues, and replay. These functions help teams distribute messages, retain useful event history, and handle workloads that need partitioned consumption. Delivery is at-least-once, so applications must account for possible redelivery when designing consumers.

Protocol coverage is broad: AMQP, Kafka, MQTT, REST, and WebSocket are supported, alongside programming-language APIs. Client languages include C, C#/.NET, Go, Java, Java RTO, JCSMP, Jakarta Messaging, JavaScript, Node.js, Python, and iOS. This breadth reduces the need to standardize every producer and consumer on one client stack. Stream processing and a schema registry are not part of the product, which makes it less suitable when those are required as built-in capabilities.

Supported micro-integrations connect applications, cloud services, and integration tools. Custom dashboards and alerts provide operational monitoring, while broker-native distributed tracing uses OpenTelemetry. Those controls are useful for teams responsible for tracing event flows across services rather than inspecting each component in isolation.

Solace Cloud event broker services enable secure protocol ports by default and disable plain-text ports by default. Solace states that the infrastructure supporting customer event broker services, Solace Home Cloud, and Cloud Console complies with GDPR, SOC 2 Type 2, and ISO 27001. Standard support covers 24x7x365 product-defect and outage resolution; Advanced and Advanced+ support list response times of 30 and 15 minutes respectively.

Pricing

PubSub+ uses a freemium model. The Solace Cloud Event Broker Trial costs nothing and provides a cloud event broker service for 30 days. It is a time-limited way to validate cloud deployment and integration before committing to a longer arrangement.

The Solace Event Broker Software Free Version also costs nothing. It is enterprise-grade software intended to run anywhere and is ready for IaaS or PaaS deployment. This is the strongest starting point for teams that can operate the broker themselves and want to avoid an initial license charge.

Paid cloud capacity is organized from ENT-250 through ENT-100K. Maximum concurrent connections and queues range from 250 to 100,000, with configurable storage up to 6 TB. Paid plans use custom pricing, so organizations must size capacity and obtain a commercial quote. The lower tiers suit contained workloads; larger tiers are aimed at broad, high-concurrency estates. Standard support is included as the baseline support level, while Advanced and Advanced+ are the choices for faster stated response times.

Platforms

Supported platforms are API, Linux, self-hosted, and web. The hybrid deployment model covers cloud service, software, and appliance options, allowing the same broker strategy to extend from centralized infrastructure to remote locations.

Who it's for

Choose PubSub+ when an enterprise needs one event-broker approach across clouds, data centers, and edge sites, especially when teams must accommodate Kafka, MQTT, AMQP, REST, and WebSocket clients together. It also fits organizations that value replay, partitioned queues, dashboards, alerts, and OpenTelemetry tracing in the broker layer.

Look elsewhere if stream processing or a schema registry is a required part of the platform, or if the workload does not justify evaluating custom capacity tiers and hybrid deployment options.

Pros and cons

• Pro: Event-mesh routing spans clouds, data centers, and geographies, supporting genuinely distributed architectures.
• Pro: AMQP, Kafka, MQTT, REST, WebSocket, and extensive language support accommodate mixed client estates.
• Pro: Cloud, software, and appliance deployments support hybrid and remote-location requirements.
• Pro: The free software version and 30-day cloud trial provide two low-cost entry paths.
• Con: Delivery is at-least-once, so consumers must handle redelivery.
• Con: Stream processing and schema registry capabilities are absent.
• Con: Paid tiers have custom pricing, and capacity selection spans a wide range from 250 to 100,000 connections and queues.

Alternatives

For a wider survey, see Event Streaming Platforms, Message Queue (MQ) Software, and Message Broker Software.

Lightstreamer is a freemium option with a demo license capped at 20 concurrent client connections and broader listed platform coverage; choose it when that smaller connection limit fits.

Aiven for Apache Kafka offers a free tier with 250 KiB/s throughput, three days of retention, five topics, and two partitions per topic, making it a better fit for a tightly bounded Kafka workload.

Apache Pulsar is free, open-source software from the Apache Software Foundation; choose it when that project model is the priority.

Apache RocketMQ is free open-source software under the Apache License 2.0, suitable when that licensing and self-managed approach match your needs.

Confluent Cloud provides a free Basic tier with serverless managed clusters, autoscaling Kafka resources, and more than 80 managed connectors; choose it for a managed Kafka-centered service.

DataStax Astra Streaming is a freemium streaming service with a free tier and usage-based paid plans.

Apache Kafka is free to download and self-host, with no formal or commercial support from the Apache Software Foundation; choose it when a direct open-source Kafka deployment is preferable.

RisingWave is Apache 2.0 open source when self-managed and also has paid plans; choose it when its stream-processing focus is the deciding factor.

Verdict

PubSub+ Event Broker is a strong choice for enterprises that need protocol diversity, event-mesh routing, and deployment freedom across cloud, on-premises, and edge environments. Its free software version and 30-day trial lower the barrier to evaluation. Look elsewhere when built-in stream processing or schema management is essential, or when custom-priced capacity planning is more complexity than the workload warrants.