Ably vs Google Cloud Pub/Sub

Discover how Google Cloud Pub/Sub compares to Ably, and understand which is right for your use case, based on dimensions such as core features, pricing, reliability, and scalability.

What is Ably?

Ably is a realtime experience platform that provides APIs and SDKs to power realtime functionality - with no realtime infrastructure to build and maintain. Our application building blocks and integrations enable developers to quickly create live experiences from live chat and data broadcast, to collaborative UXs and notifications.

What is Google Cloud Pub/Sub?

Google Cloud Pub/Sub is a real-time messaging service. Pub/Sub is used for asynchronous messaging between different systems, and services, within your applications. It enables developers to build robust and scalable real-time applications.

Compare Ably and Google Cloud Pub/Sub

Let’s compare Ably and Google Cloud Pub/Sub, looking at key dimensions such as their core features, pricing, integrations & interoperability, quality of service, performance & availability and security & compliance.

Disclaimer: This comparison was created based on documentation and resources freely available online about Ably and Google Cloud Pub/Sub. The content was last updated on 30 Apr 2025 for Ably and on 24 Apr 2025 for Google Cloud Pub/Sub. Be sure to double-check everything before you make any decisions. If you do find anything incorrect or out of date, then please let us know.

Hear from companies gaining their realtime advantage with Ably

“

The core infrastructure for delivering live sports data to our customers is Ably. We sleep easier at night knowing it can be relied on for consistent low latency and message integrity at scale.”

Gary Williams

IT Infrastructure Team Lead

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“

Ably immediately solved our issues around the user experience and scale. It supports our customers’ stringent expectations as well as future product development.”

Max Freiert

Product Group Lead

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“

Ably copes easily with big loads. We don’t have to worry about stability, even when we get huge traffic spikes.”

Johan Bengtsson

CTO

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Ably has built reliable realtime infrastructure so you don’t have to. On our free plan you benefit from:

6M monthly messages
200 concurrent channels
200 concurrent connections

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	Ably	Google Cloud Pub/Sub	Why this matters
Core features
Pub/Sub messaging	Reduces communication code complexity, simplifying the process of building highly functional and architecturally complex realtime apps.	Ably Yes Ably provides robust pub/sub messaging capabilities over serverless WebSockets.	Google Cloud Pub/Sub Yes	Reduces communication code complexity, simplifying the process of building highly functional and architecturally complex realtime apps.
Chat capabilities	Accelerates the time to implement rich chat experiences with features such as read receipts, typing indicators, and more.	Ably Yes Ably Chat provides dedicated APIs for building out a scalable chat solution. We support individual and group messaging, typing indicators, room reactions, and more. Learn more about Ably Chat	Google Cloud Pub/Sub No Chat features such as group chat, emojis, and file sharing are not supported by Google Pub/Sub out of the box, which is intended to be used for service-to-service communication.	Accelerates the time to implement rich chat experiences with features such as read receipts, typing indicators, and more.
Collaboration capabilities	Enables you to quickly integrate realtime collaborative features like live cursors, member location, avatar stacks, and component locking.	Ably Yes The Spaces SDK provides an opinionated set of abstractions for collaborative environments including live cursors, avatar stacks and component locking. Learn more	Google Cloud Pub/Sub No Google Pub/Sub recommends using other Google services like Firebase Realtime database to build applications that require functionalities like collaboration. Read more	Enables you to quickly integrate realtime collaborative features like live cursors, member location, avatar stacks, and component locking.
State sync capabilities	Enables realtime data synchronization across devices and users, ensuring a cohesive and up-to-date user experience.	Ably Yes Ably provides a self-hostable and managed database connector to stream updates over our serverless WebSocket platform. Ably also provides the Models SDK for seamless connector interactions. Learn more	Google Cloud Pub/Sub No Google Pub/Sub does not support a state sync feature out of the box, but this can be achieved in combination with a realtime database.	Enables realtime data synchronization across devices and users, ensuring a cohesive and up-to-date user experience.
Presence	Maintaining a view of which users are connected, and their associated metadata, enables their online status to be updated in realtime.	Ably Yes	Google Cloud Pub/Sub No	Maintaining a view of which users are connected, and their associated metadata, enables their online status to be updated in realtime.
Occupancy	High-level metrics about the clients currently connected to a channel make it simple to show things such as connected user count, or display which channels are the most popular.	Ably Yes	Google Cloud Pub/Sub Yes Google Pub/Sub provides monitoring dashboards that can be used to monitor subscriptions. Subscriptions can also be monitored through the Cloud Monitoring API. Read more	High-level metrics about the clients currently connected to a channel make it simple to show things such as connected user count, or display which channels are the most popular.
Message interactions	Enables interaction with previously-sent messages, facilitating the implementation of features like message reactions and threads.	Ably Partial Message interactions are natively supported in ably-js. There is not currently any API support for retrieving messages and their interactions efficiently from the Realtime service (under development). Learn more	Google Cloud Pub/Sub No	Enables interaction with previously-sent messages, facilitating the implementation of features like message reactions and threads.
Message history	Enables clients to catch up on missed messages when inactive, ensuring a user doesn’t miss any important messages.	Ably Yes	Google Cloud Pub/Sub No Pub/Sub can't retrieve acknowledged messages. You can use the Seek feature to mark them as unacknowledged and redeliver them or delete unacknowledged messages. Read more	Enables clients to catch up on missed messages when inactive, ensuring a user doesn’t miss any important messages.
Push notifications	Cross-platform push notifications make it possible to deliver important and timely messages to users even when they’re inactive.	Ably Yes Support for Android and iOS push notifications. Improved web-push for browsers currently in progress.	Google Cloud Pub/Sub Yes You can create a push subscription workflow for push notifications using Google Pub/Sub. Read more	Cross-platform push notifications make it possible to deliver important and timely messages to users even when they’re inactive.
Message delta compression	Minimizes bandwidth and can reduce latency, particularly in scenarios where continuous updates are sent.	Ably Yes Broadcast changes efficiently with our binary deltas, reducing bandwidth consumption by typically up to 95%.	Google Cloud Pub/Sub No	Minimizes bandwidth and can reduce latency, particularly in scenarios where continuous updates are sent.
Programmatic management	Enables the automation of provisioning, management, and testing of service resources, simplifying integration with existing development workflows such as CI.	Ably Yes	Google Cloud Pub/Sub Yes	Enables the automation of provisioning, management, and testing of service resources, simplifying integration with existing development workflows such as CI.
Pricing
Free plan	With a free plan, you can test the service’s functionality and compatibility with your project before committing to a paid plan.	Ably Yes	Google Cloud Pub/Sub No	With a free plan, you can test the service’s functionality and compatibility with your project before committing to a paid plan.
Pricing model	The pricing model should align with your project's expected load, usage patterns, and budget in order to be cost-effective and efficient.	Ably Ably offers a per-minute, consumption-based pricing model. This gives granular control over your costs, eliminating the need to pay for peak users or connections.	Google Cloud Pub/Sub Google Pub/Sub has usage-based pricing, based the number of published, delivered, and stored bytes. Read more	The pricing model should align with your project's expected load, usage patterns, and budget in order to be cost-effective and efficient.
Pricing plans	The pricing plans offered by cost.	Ably The free and paid plans are: Free plan: Up to 6 million monthly messages and 200 concurrent connections Standard plan ($29/month): Up to 10k concurrent connections and channels, and 2.5k messages/second Pro plan ($399/month): Up to 50k concurrent connections and channels, and 10k messages/second Enterprise plan: For committed use, with custom pricing Learn more		The pricing plans offered by cost.
Integrations & interoperability
SDKs	Supporting multiple languages and platforms offers greater flexibility when building cross-platform realtime apps.	Ably Java Javascript (browsers) React Native React Hooks Android Clojure Cordova / Phonegap Flutter Go iOS Objective-C iOS Swift Kotlin Laravel (PHP) MacOS Mono NativeScript .NET Node.js PHP (REST only) Scala Python Ruby (REST only) tvOS Unity Xamarin + Xamarin.forms	Google Cloud Pub/Sub C++ C# Go Java Node.js PHP Python Ruby	Supporting multiple languages and platforms offers greater flexibility when building cross-platform realtime apps.
Supported realtime protocols	Support for multiple protocols provides the flexibility to choose a protocol that best suits your project’s requirements.	Ably WebSockets MQTT Server-Sent Events (SSE) Fallback to Comet (XHR) and Long Polling for older browsers	Google Cloud Pub/Sub None. Google Pub/Sub does not natively support any real-time protocols. However, you can implement WebSockets using other Google services like Google's Compute Engine.	Support for multiple protocols provides the flexibility to choose a protocol that best suits your project’s requirements.
Serverless functions	Enables integration with third-party cloud providers by facilitating the execution of custom code against messages to perform business logic like on-the-fly translation.	Ably AWS Lambda Microsoft Azure Functions Cloudflare Workers Google Cloud Functions	Google Cloud Pub/Sub Google Cloud Functions	Enables integration with third-party cloud providers by facilitating the execution of custom code against messages to perform business logic like on-the-fly translation.
Streaming & queueing	Provides a dependable method to reroute messages from the service to third-party streams and queues for further processing.	Ably Egress: Kafka Kinesis AMQP SQS Pulsar Ably-hosted queues Ingress: Kafka Connector Postgress (via Database Connector) The Database Connector is designed for any database in the SQL-family, but at the moment only supports Postgres. Please contact us if you want support in other databases.	Google Cloud Pub/Sub Yes	Provides a dependable method to reroute messages from the service to third-party streams and queues for further processing.
Observability services	Enables realtime monitoring and troubleshooting by offering insights into service behavior directly in your observability platform of choice.	Ably Yes	Google Cloud Pub/Sub Yes The Google Monitoring, Alerting and Logging integration provides observability services. Read more	Enables realtime monitoring and troubleshooting by offering insights into service behavior directly in your observability platform of choice.
CI/CD tools	Makes it possible to provision and configure service infrastructure as part of a CI or CD pipeline, enabling repeatable and reliable deployments.	Ably Terraform Control API + SDKs	Google Cloud Pub/Sub Yes Supports: Jenkins Google Cloud Build	Makes it possible to provision and configure service infrastructure as part of a CI or CD pipeline, enabling repeatable and reliable deployments.
Quality of Service
Scalability	Scalability is vital as it ensures the service can handle increased data load or users without compromising performance.	Ably <50 ms median global latency 2 trillion+ monthly transactions 1 billion monthly device connections 99.999% uptime SLA Unlimited throughput capacity at system level, limitless channel churn rate	Google Cloud Pub/Sub Google Pub/Sub is built to be scalable and reliable. Google uses the service for their products to send billions of messages per day. You can read more about their architecture and limitations in their documentation.	Scalability is vital as it ensures the service can handle increased data load or users without compromising performance.
Guaranteed message delivery	Ensures messages are never lost during transmission, even in the presence of network disruptions.	Ably Yes	Google Cloud Pub/Sub Yes	Ensures messages are never lost during transmission, even in the presence of network disruptions.
Guaranteed message ordering	Maintains the sequence of messages as they were sent. This is particularly important in apps where the chronological order of messages is essential for meaningful communication.	Ably Yes	Google Cloud Pub/Sub No Google Pub/Sub supports message ordering, but cannot always guarantee it even when this is enabled - for example, when dead-letter topics are enabled on subscriptions. Read more	Maintains the sequence of messages as they were sent. This is particularly important in apps where the chronological order of messages is essential for meaningful communication.
Exactly-once message delivery	Guarantees that each message is processed exactly once, preventing data inconsistencies that can arise from duplicate processing or missing messages.	Ably Yes	Google Cloud Pub/Sub Yes Google Pub/Sub supports exactly-once delivery based on a Pub/Sub-defined unique message ID. Read more	Guarantees that each message is processed exactly once, preventing data inconsistencies that can arise from duplicate processing or missing messages.
Performance & availability
Uptime Guarantee	An uptime guarantee instills confidence in the reliability of the service and protects your business from the negative impacts of downtime.	Ably 99.999%	Google Cloud Pub/Sub 99.95% Read more	An uptime guarantee instills confidence in the reliability of the service and protects your business from the negative impacts of downtime.
Global edge network	By bringing servers (Points of Presence, or PoP) geographically closer to the devices of end users, and routing requests to the nearest PoP, global latency is reduced to a minimum.	Ably Yes All Ably customer data runs across all our 7 geographically-distributed core routing datacenters by default. Ably's network of 385 edge acceleration points-of-presence is growing day by day.	Google Cloud Pub/Sub Yes	By bringing servers (Points of Presence, or PoP) geographically closer to the devices of end users, and routing requests to the nearest PoP, global latency is reduced to a minimum.
Multi-region data replication (message durability)	By replicating data across multiple regions, the risk of data loss or downtime is greatly mitigated since if data is lost or a server fails in one region, the information can be retrieved from another.	Ably Yes	Google Cloud Pub/Sub Yes Google Pub/Sub supports synchronous data replication across three zones.	By replicating data across multiple regions, the risk of data loss or downtime is greatly mitigated since if data is lost or a server fails in one region, the information can be retrieved from another.
No single point of failure or congestion	Having no single point of failure means a system is resilient and can continue to operate even if one part fails. Avoiding a single point of congestion ensures messages flow efficiently across the system and avoids bottlenecks that could lead to performance issues under load.	Ably Yes	Google Cloud Pub/Sub Yes	Having no single point of failure means a system is resilient and can continue to operate even if one part fails. Avoiding a single point of congestion ensures messages flow efficiently across the system and avoids bottlenecks that could lead to performance issues under load.
Latency	Low latency is crucial for realtime apps as it ensures swift and efficient data transmissions, providing a smoother and more responsive user experience.	Ably <50ms round trip latency for the 99th percentile; <35ms latency once traffic arrives within AWS	Google Cloud Pub/Sub 100ms round trip	Low latency is crucial for realtime apps as it ensures swift and efficient data transmissions, providing a smoother and more responsive user experience.
Security & compliance
API key authentication	Simplifies the authentication code on trusted servers compared to requesting, managing, and refreshing tokens.	Ably Yes	Google Cloud Pub/Sub No Google Pub/Sub only supports gcloud CLI credential and Application Default Credentials (ADC). Read more	Simplifies the authentication code on trusted servers compared to requesting, managing, and refreshing tokens.
Token-based authentication	Provides a means to securely authenticate user devices against your user management system.	Ably Yes	Google Cloud Pub/Sub Yes	Provides a means to securely authenticate user devices against your user management system.
Single Sign-On (SSO) authentication	SSO streamlines login processes, boosts security by minimizing password use, and meets compliance needs for secure data access management.	Ably Yes	Google Cloud Pub/Sub Yes SSO authentication in Pub/Sub is supported through Google Cloud IAM, OAuth 2.0, and Workforce Identity Federation, allowing integration with external identity providers like Azure AD or Okta. Read more	SSO streamlines login processes, boosts security by minimizing password use, and meets compliance needs for secure data access management.
Rules for permissions and operations	Provides control over which users can subscribe and publish to certain channels.	Ably Yes	Google Cloud Pub/Sub Yes Rules for permissions and operation can be configured using Identity and Access Management (IAM). Read more	Provides control over which users can subscribe and publish to certain channels.
End-to-end encryption	Ensures that the data transmitted between the client and the API server remains confidential and secure while in transit.	Ably Yes Ably offers SSL/TLS encryption and 256-bit AES encryption using private keys. Message payloads can only be decrypted by other clients that share your secret key. Learn more about Ably's encryption	Google Cloud Pub/Sub Yes	Ensures that the data transmitted between the client and the API server remains confidential and secure while in transit.
Encryption at rest	Ensures data stored by the service is secure and compliant, while also mitigating the risks of a data breach.	Ably Yes	Google Cloud Pub/Sub Yes	Ensures data stored by the service is secure and compliant, while also mitigating the risks of a data breach.
Compliance	Compliance with regulations can impact your ability to meet legal obligations in your industry.	Ably SOC 2 certified HIPAA compliant EU GDPR compliant Ably also offers EU and US-only data storage.	Google Cloud Pub/Sub HIPAA	Compliance with regulations can impact your ability to meet legal obligations in your industry.