Google Eventarc Alternatives for Event-Driven Architectures: Comparing Hookdeck Event Gateway, Amazon EventBridge, Azure Event Grid, and Confluent Kafka

If you're building an event-driven architecture in Google Cloud then you've probably already taken a look at Google Eventarc. But before you commit, it's worth considering some of the alternatives to Google Eventarc to see if they are more flexible and offer a more complete solution.

In this comparison article, we'll look at four Google Eventarc alternatives and consider how well they:

• Integrate with data sources and data destinations
• Transform and enrich data in-flight
• Handle failure
• Ease the developer experience

The alternatives we'll consider are Hookdeck, Amazon EventBridge, Azure Event Grid, and Confluent's managed Kafka.

So, before you decide on Google Eventarc, read on to make sure you're making the right choice.

Comparing Google Eventarc alternatives

At the heart of every event-driven architecture is an event gateway tool that ingests events and then delivers them to a destination. But beyond that basic functionality, there's a huge variety in the approaches that different event gateway tools take.

Some, like Eventarc, focus on moving events from one place to another and rely on additional tools for anything more complex. While others, such as Hookdeck, offer a more complete solution in one tool. The scope for variety is so big that even within the Google Cloud ecosystem, Eventarc sits alongside Google Pub/Sub, which takes a different approach.

So, to make our comparison manageable, we need a common set of criteria:

• Integrations with event sources and destinations: Does it work with your existing tooling? How easy is it to set-up new integrations?
• Does it offer rich in-flight processing? Or do you need to integrate other tools to transform and enrich events?
• Can it store events? Almost every event gateway can store events long enough to retry delivery but what if you need something longer-term?
• What auth options does it offer? Authenticating, authorizing, and signing data sources and destinations is part and parcel of running an event gateway. Does it offer common standards and integrations or does the tool lean too heavily on the cloud vendor's own IAM system?
• Is observability built-in? Most event gateways integrate with third-party tools like Datadog, whereas some also provide their own monitoring dashboard and tooling.
• Does it offer a good developer and operator experience? Each of the tools we're considering is a managed service but they each make different demands of you. We'll look at what that means for each alternative to Eventarc.

What is Google Eventarc

Google Eventarc now comes in two tiers: Eventarc Standard and Eventarc Advanced. Standard is a tool for ingesting events and delivering them to destinations within the Google Cloud ecosystem. Eventarc Advanced significantly expands the platform's capabilities with message routing, filtering, transformation, and delivery between services — including external HTTP endpoints. Both tiers work with the CNCF's CloudEvents format.

For example, let's say you have a Google Cloud Function that performs currency conversions as part of an e-commerce system. Your frontend calls an API endpoint managed by Google API Gateway and that emits an event into Eventarc. According to rules you've already defined, Eventarc then delivers the request to your currency converting Cloud Function.

In a typical environment, that would be just one of many scenarios where Eventarc acts as the communication layer between different systems within your event-driven architecture. Ideally, Eventarc would sit at the center of each part of your application's tech stack and manage the communication between them.

To understand whether Eventarc is up to the job, we'll first need to understand more about the approach each tier takes.

Google Eventarc key features

Let's start with a quick summary of what makes Google Eventarc tick:

• Event pattern: When events come into Eventarc, it checks them against predefined rules. If there is a match, Eventarc sends the event on to the destination defined in the rule.
• Event format: Supports the CNCF's CloudEvents standard.
• Event integrations: Eventarc Standard consumes events from many Google Cloud services, such as BigQuery, Firebase, and API Gateway. It can integrate directly with a limited number of external sources, such as Datadog and Lacework. Standard is more limited when it comes to delivery, integrating with just a few systems including Google Cloud Functions, Google Cloud Run, and Google Kubernetes Engine. Eventarc Advanced broadens this with support for routing events between Google Cloud services and external HTTP endpoints.
• Processing: Eventarc Standard doesn't make any changes to events, meaning you'll need to route events to other tools for transformations and enrichment. Eventarc Advanced supports message transformation and enrichment pipelines.
• Storage: Other than storing failed events to retry them, Eventarc doesn't offer event persistence.
• Routing: Eventarc can route events to different destinations according to where they come from, their data, and their metadata.
• Observability: Eventarc doesn't have its own monitoring but it does integrate with both Google Cloud Logging and Google Cloud Monitoring.
• Error management and recovery: Eventarc retries events for up to 24 hours and can route failures to a dead-letter topic, but this must be configured manually in Google Pub/Sub.
• Operational impact: Eventarc is serverless, meaning it should have a low impact on your operations team.

Those are the fundamentals of Eventarc, so what does it do well and where is it lacking?

Google Eventarc advantages

• Two tiers for different needs: Eventarc Standard offers simplicity for Google-only workflows, while Eventarc Advanced provides routing, filtering, transformation, and external HTTP delivery for more complex architectures.
• Supports a standard event format: The CNCF CloudEvents standard could simplify integrating with external sources that also support that format.
• Scales on demand: Eventarc scales as and when you need it to, within some limits.
• External delivery with Advanced: Eventarc Advanced can deliver events to external HTTP destinations, closing one of Standard's biggest gaps.

Google Eventarc disadvantages

• Standard is heavily focused on Google integrations: Eventarc Standard is suitable if you only integrate with Google Cloud products. Consuming events from external sources is possible if you can first route them to another Google tool such as Pub/Sub or API Gateway. However, Standard does not integrate directly with external data destinations. Eventarc Advanced addresses this limitation with support for external HTTP endpoints.
• Processing requires Advanced tier: If you need to transform or enrich events, Eventarc Standard asks that you direct them to another tool. Eventarc Advanced adds transformation and enrichment pipelines, but this capability is not available in Standard.
• Events are effectively ephemeral: Beyond storing events to enable retries, Eventarc disposes of them once they've passed through the system. To store events, you'll need to route them to another tool.

Google Eventarc alternatives

Now that we've seen what Eventarc offers across its Standard and Advanced tiers, we should find out whether the four alternatives we're considering offer a better solution. Of course, the final answer will depend on the needs of your project, but we can get a clearer picture by looking in detail at:

• Hookdeck Event Gateway: Comprehensive event gateway solution with 120+ pre-configured sources that ingests events over HTTP, offers complex in-flight processing, and can push events out to any HTTP destination.
• Amazon EventBridge: Point-to-point event delivery with some limited in-flight processing. However, thanks to its custom event format and reliance on a custom API for integrations, it can be somewhat more difficult to work with than Hookdeck, for example.
• Azure Event Grid: Publish-subscribe event routing tool that can ingest events using both HTTP and MQTT, with expanded MQTT broker capabilities including WebSocket transport, custom domains, and Microsoft Entra JWT authentication.
• Confluent Kafka: Managed pub-sub event streaming with Kafka. Feature rich, and extensible connectivity via add-ons, yet complex to set up and manage. Now built on Apache Kafka 4.0 with KRaft mode and Kafka Queues via share groups.

Hookdeck Event Gateway

Hookdeck Event Gateway is an integrated, end-to-end event gateway that can consume, process, and deliver messages throughout your event-based system. A key distinction from Eventarc lies in Event Gateway's all-in-one approach. Using Event Gateway, you can get everything you need without having to find, set up, and manage other tools.

Hookdeck Event Gateway key features

• 120+ pre-configured sources: Event Gateway ships with over 120 pre-configured source types that auto-configure authentication, signature verification, and response formatting for providers like Stripe, Shopify, GitHub, and Twilio. No custom integration code required.
• Webhook, API, and generic HTTP ingestion: Thanks to its support for webhooks and inbound API calls, Event Gateway consumes events from a broad variety of sources without the need for custom integration work. Similarly, Event Gateway can send data to a wide variety of existing destinations using outbound webhooks.
• Complex event processing: Event Gateway lets you run your own JavaScript code to transform and enrich event payloads via both a code editor and a visual editor.
• Filtering and routing: You can use payload data to selectively filter events and control their final destination, with fan-out to multiple destinations and multiplexing across sources.
• Standard auth and verification: Event Gateway supports HMAC, Basic Auth, Bearer Token, and API key verification for a growing number of services and generic signing methods to verify webhook handshaking and payload verification.
• Define event pipelines using the UI, API, CLI, or with Terraform: Define event routing, filtering, transformations, authentication, and more in the way that best fits your development process.
• Error management and recovery: Event Gateway provides an issue notification and tracking feature with configurable issue triggers, and a feature that allows you to retry events, including automatic and bulk retries to recover from unexpected downtime.
• Built-in observability: Event Gateway provides end-to-end observability with full-text search across your entire event history, visual event traces, and metrics export to Datadog, Prometheus, and New Relic — all from within the same interface where you manage the pipelines themselves.

How does Hookdeck Event Gateway shape up against Google Eventarc?

Event Gateway and Eventarc take fundamentally different approaches.

The most noticeable difference is that Event Gateway is a standalone solution that takes care of the end-to-end ingestion, filtering, processing, and delivery of your events. Even with Eventarc Advanced's expanded capabilities, Eventarc still relies on other Google Cloud tools for full functionality. Event Gateway gives you everything you need in one serverless platform.

Event Gateway's support in-platform for event processing via JavaScript gives you much more control without having to use external tools, while its configurable storage gives you greater flexibility over how to handle event retries.

Amazon EventBridge

Amazon's offering in this space is EventBridge. EventBridge comes in three versions, each tailored to specific use cases:

• Event Bus: This is the closest to Google Eventarc, offering point-to-point routing between multiple sources and destinations.
• Pipes: Designed for ETL-like workloads, Pipes provides fixed connections between sources and destinations with more sophisticated in-flight processing.
• Scheduler: Allows you to time the delivery of events in a cron-like fashion, ideal for scheduled tasks.

Amazon EventBridge key features

• Point-to-point event delivery: Connect sources and destinations directly, using rules to decide which events get delivered where.
• Event format: Unlike Eventarc, which relies on the CloudEvents standard, EventBridge has its own event format.
• Consuming events: When it comes to the AWS ecosystem, EventBridge's data source support is roughly equivalent to Eventarc's in the Google ecosystem. However, EventBridge offers some more flexibility for external event sources through the PutEvents API, Java SDK, and CLI.
• Event consumers: EventArc's major failing is its lack of support for external destinations. EventBridge does a much better job in this regard, supporting webhooks and third-party APIs, as well as delivery to AWS products.
• Lightweight processing: EventBridge offers simple in-flight text transformations. For more complex processing, you'll need to integrate with your own Lambda functions or other systems.
• Archival storage: Like all the options we're comparing, EventBridge stores failed events so that it can attempt re-delivery. It also offers event archival so you can replay events later.

How does Amazon EventBridge compare to Google Eventarc?

Choosing between Amazon EventBridge and Google Eventarc is mostly down to whether you're already committed to the AWS or GCP ecosystem. With Eventarc Advanced, Google has closed some of the gaps that previously made EventBridge more capable — Advanced now supports external HTTP delivery and in-flight processing. However, if you haven't yet decided on one public cloud over another, here's how they compare.

Azure Event Grid

Just like Google Eventarc and Amazon EventBridge, Azure Event Grid will be of most interest if you are already working with its parent cloud platform. However, Event Grid has much more to offer than its Google and Amazon counterparts.

Event Grid uses a pub-sub model, where event consumers subscribe to named topics rather than specifying each destination for a trigger or rule. This model simplifies management as your system grows. It streamlines handling multiple destinations, making scalability and maintenance easier.

Another standout feature is that Event Grid provides two ways to consume external events: MQTT and HTTP pull delivery. Event Grid's MQTT broker capabilities have expanded significantly, with support for MQTT, WebSocket transport, custom domains, client lifecycle events, retained messages, and Microsoft Entra JWT authentication. This gives you more options for integrating with different systems with minimal need for custom development.

Azure Event Grid key features

• Publish-subscribe: As your event-driven architecture grows, with more integrations and a greater flow of events, Event Grid's pub-sub model could be easier to scale thanks to decoupling event producers from event consumers.
• Ingests MQTT and webhooks: Like Eventarc, Event Grid integrates directly with products from its own cloud ecosystem. But what makes Event Grid particularly interesting is that it reduces the work of integrating with external data sources through its support for MQTT, webhooks, and the CNCF CloudEvents standard.
• No rich in-flight processing: If you want to transform or enrich events, then you'll need to route them out to another tool.
• Lacks storage: Similar to Eventarc, Event Grid only stores events when it needs to retry a failed operation.

How does Azure Event Grid shape up against Google Eventarc?

With Eventarc Advanced, Google has narrowed the gap between Eventarc and Event Grid. Both now support external HTTP delivery and Event Grid's pub-sub model still offers scalability advantages. Event Grid's expanded MQTT broker capabilities give it an edge for IoT and device-oriented use cases.

The pub-sub model simplifies the process of adding or removing event consumers because you can unsubscribe the relevant consumers from the topic instead of needing to amend a rule or trigger. However, if you want to centralize control of your event routing, then Eventarc's approach of configuring destinations using triggers and rules might be more suitable.

Confluent Kafka

Kafka is the most versatile and complex of the alternatives. It offers great flexibility, but that comes at the cost of operational and development complexity.

With the release of Apache Kafka 4.0, the platform now runs entirely without ZooKeeper using KRaft mode by default, simplifying cluster management. Confluent Platform 8.0, built on Kafka 4.0, adds Kafka Queues (via share groups) for point-to-point messaging alongside the traditional pub/sub model.

Confluent's managed service simplifies running Kafka, but its operational footprint will inevitably be larger compared to Eventarc, Hookdeck, Event Grid, or EventBridge.

Whether you should use Kafka comes down to three questions:

• Do you need control over every aspect of the event's life cycle within your system?
• Do you need long-term event storage with the option for playback?
• Do you have the development and operational expertise to make the most of Kafka's potential?

Confluent Kafka key features

• It can do a lot but at a price: Kafka started as a solution for LinkedIn to handle large data volumes. It has since evolved into a sophisticated event processing and streaming platform that integrates with diverse systems. However, Kafka's extensive capabilities come at a cost. Be prepared to allocate significant time for development and operational maintenance.
• Learning curve: If you don't already have Kafka skills on your team, you'll either need to hire individuals with these skills or allocate time for learning and development.
• Pub/Sub: Kafka's data model is built around an append-only log and the pub/sub model. Event consumers subscribe to topics, while producers publish events to them.
• Open ended storage: Kafka stores every event, and you can choose how long you want to keep them. That's ideal if you need the ability to replay events or bring new consumers up to speed.
• Lots of integrations: As well as Confluent's REST proxy for ingesting events via HTTP requests, Kafka boasts direct integrations with many different tools. That includes kSQL, which allows you to query and transform Kafka data using SQL, and a Java real-time stream processing tool in the form of Kafka Streams.

How does Confluent Kafka shape up against Google Eventarc?

Comparing Kafka with almost any other tool is tricky because it almost exists in a category of its own. Even its closest rival, Amazon Kinesis, lacks the ecosystem that Kafka offers. However, the biggest difference between Kafka and Eventarc is that no version of Kafka is serverless. You'll need to devote more of your team's time to running Kafka than any of the other products we've considered here.

With Eventarc Advanced now offering transformation and external HTTP delivery, the gap between Eventarc and Kafka has narrowed somewhat. But Kafka still offers significantly deeper processing, storage, and ecosystem capabilities.

So, unless you have a use case that can be served only by Kafka, then you might find it demands more of your team than the value it can offer in return.

If you need greater functionality than Eventarc can offer, with the flexibility of a cloud-neutral tool, Hookdeck is a better choice as an event gateway solution.

Reviewing Google Eventarc alternatives

Your choice of event gateway tooling significantly impacts your ability to deliver reliable functionality, minimize operational costs, and meet deadlines.

With the introduction of Eventarc Advanced, Google has significantly expanded Eventarc's capabilities — adding transformation, routing, and external HTTP delivery. However, if you're not already committed to the Google Cloud ecosystem, Eventarc may still not offer significant advantages over its alternatives. Even with Advanced, you may find yourself using additional Google Cloud tools to fill in the gaps.

In choosing your event gateway tooling, you should consider:

• How easy it is to work with, both from a development and operational viewpoint.
• Does it have the integrations you need? If it doesn't, how easy is it to add them? Is it likely to keep pace in the future as you need to integrate with new tools?
• Does it give you the control you need over filtering, routing, transforming, and enriching events?
• Can you feel confident that you understand what's going on under the hood, thanks to its monitoring tooling?
• How does it cope when things go wrong?

For a deeper review of the options available, see our in-depth comparison of five of the most popular event gateway tools.