PubNub vs Socket.IO

Discover how PubNub compares to Socket.IO, and understand which is right for your use case, based on dimensions such as core features, pricing, reliability, and scalability.

What is PubNub?

PubNub is a developer API platform that powers the realtime infrastructure in apps to build engaging Virtual Spaces where online communities can connect. It can serve as the foundation for online chat, live events, geolocation, remote IoT control, and realtime updates.

When to use PubNub

Pros and cons of PubNub

What is Socket.IO?

Socket.IO is a library created in 2010 that provides realtime, bi-directional communication between clients and servers. It allows the management of connections, sending and receiving messages, and more. Built on top of the WebSocket protocol, it provides additional capabilities compared to raw WebSockets. WebTransport (a WebSocket alternative) is also supported.

When to use Socket.IO

Pros and cons of Socket.IO

Compare PubNub and Socket.IO

Let’s compare PubNub and Socket.IO, 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 PubNub and Socket.IO. The content was last updated on 30 Apr 2025 for PubNub and on 24 Apr 2025 for Socket.IO. 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 If you do find anything incorrect or out of date, then please let us know.

Alternatives to PubNub and Socket.IO

While both PubNub and Socket.IO are worth considering as options for realtime experiences, they aren’t without their limitations. We suggest evaluating them against the following alternatives to make sure you find the right solution for your needs.

Alternatives to PubNub

Pusher is a first-generation pub/sub messaging service that provides bi-directional hosted APIs for adding realtime features to applications.

Socket.IO is a library that provides realtime, bi-directional communication between clients and servers. It allows the management of connections, sending and receiving messages, and more.

SignalR is an open-source library that simplifies adding real-time web functionality to ASP.NET Core web apps.

See more alternatives to PubNub

Alternatives to Socket.IO

Azure SignalR is an Azure-hosted, fully managed realtime framework built on top of an open-source software library for Microsoft ASP.NET.

Firebase Realtime Database is a cloud-hosted database by Google, allowing developers to build realtime applications for web and mobile.

PubNub is a developer API platform that powers the realtime infrastructure in apps to build engaging Virtual Spaces where online communities can connect.

See more alternatives to Socket.IO

Discover how PubNub and Socket.IO stack up against Ably

Ably is the definitive realtime experience platform of the internet. See how we compare to PubNub and Socket.IO on key dimensions such as core features, pricing, integrations, QoS, performance, and security and compliance.

Ably vs PubNub Ably vs Socket.IO

Try Ably for free to discover the benefits for yourself

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

Get started for free

	PubNub	Socket.IO	Why this matters
Core features
Pub/Sub messaging	Reduces communication code complexity, simplifying the process of building highly functional and architecturally complex realtime apps.	PubNub Yes	Socket.IO No Need to rely on a third party - e.g. use a Redis adapter to broadcast events to clients through the Redis pub/sub mechanism. Read more	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.	PubNub Yes See PubNub Chat Docs	Socket.IO Partial As it's a library, you need to create the chat capabilities yourself. But this can be done using Socket.IO.	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.	PubNub Partial PubNub's collaboration capabilities are largely powered by its Presence feature. There is no dedicated collaboration SDK.	Socket.IO Partial As it's a library, you need to implement collaboration capabilities yourself. But you can do this using Socket.IO itself.	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.	PubNub Yes	Socket.IO No The library does not support this. You would need to create a bespoke state sync capability or integrate a third party library to get state synchronisation.	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.	PubNub Yes Read more	Socket.IO Partial It is the duty of your application to link a Socket.IO connection to a user account. Read more	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.	PubNub Yes PubNub's Presence API allows developers to access and integrate occupancy information into their applications. Read more	Socket.IO Partial Rooms are available. It is possible to query for rooms and SIDs. See 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.	PubNub Yes	Socket.IO Partial You would need to build the message interaction functionality yourself on top of Socket.IO. Learn more	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.	PubNub Yes	Socket.IO No The Socket.IO server does not store messages. Your application has to persist messages somewhere for the clients that are not currently connected. Learn 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.	PubNub Yes	Socket.IO No Socket.IO not support Push notifications. You would need to build this capability yourself and/or use another library. Learn 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.	PubNub No	Socket.IO 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.	PubNub Yes	Socket.IO Yes The Socket.IO server is initialised in code. It is possible to configure the socket.IO server's configuration in code as well. Learn more	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.	PubNub Yes	Socket.IO Yes Open Source framework that uses the MIT license.	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.	PubNub PubNub offers Free, Starter, and Pro packages. Their support packages, separate from their standard plans, also include an Enterprise option. Their pricing model is based on monthly active users (MAUs). See the pricing page	Socket.IO Free and open-source.	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.	PubNub Starter: $98/month/MAU: Up to 1000 MAUs, and up to 3000 transactions per MAU. Pro packages: Custom pricing Their support packages, separate from their standard plans, also include an Enterprise option. Overages apply: $0.15 per additional user $43 per additional 1M transactions		The pricing plans offered by cost.
Integrations & interoperability
SDKs	Supporting multiple languages and platforms offers greater flexibility when building cross-platform realtime apps.	PubNub REST API Asyncio C-Core C-Sharp Cocoa Objective-C Cocoa Swift Dart FreeRTOS Go Java JavaScript Kotlin Lua Mbed MQTT Objective-C PHP POSIX C POSIX C++ Python React Redux Ruby Rust Swift Unity Windows C Windows C++ Source: SDKs	Socket.IO Client and Server APIs only. C++ Swift Java Javascript Typescript Node.js Python Golang Rust Dart .NET Kotlin	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.	PubNub HTTP MQTT Fallback to Comet (XHR) and Long Polling for older browsers PubNub uses HTTP as the transport for their client libraries. A WebSocket compliant interface is provided in some libraries, however this is just a wrapper around an underlying HTTP transport.	Socket.IO WebSocket WebTransport HTTP	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.	PubNub PubNub operates its own serverless architecture through its feature called PubNub Functions.	Socket.IO No It is not possible to trigger serverless functions with Socket.IO on it's own. See this Reddit post for more info	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.	PubNub Egress: AWS Kinesis AWS SQS Apache Pulsar RabbitMQ AMQP Kafka Ingress: Kafka	Socket.IO No Socket.IO does not offer native queues and streaming.	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.	PubNub Yes PubNub provides integrations with Datadog and NewRelic.	Socket.IO Yes The Socket.IO admin UI can be used to have an overview of the state of your Socket.IO deployment.	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.	PubNub PubNub provides a Command Line Interface (CLI) specifically for managing and deploying PubNub Functions.	Socket.IO No	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.	PubNub 2 trillion monthly transactions 800 million device connections monthly Under 100 milliseconds delivery 99.999% reliability Source: Edge messaging solutions page	Socket.IO No published metrics. Socket.IO servers don’t communicate between them, so you need a way to route events to all clients, even if they are connected to different servers. This is made possible by using adapters, of which the Redis adapter seems to be the most popular choice.	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.	PubNub No	Socket.IO Partial By default, Socket.IO provides an "at most once" guarantee of delivery. From the client side, you can achieve an at least once guarantee with acknowledgements and timeouts.	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.	PubNub No	Socket.IO Yes Socket.IO guarantees ordering, no matter which low-level transport is used. 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.	PubNub No	Socket.IO No At least once or at most once only.	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.	PubNub PubNub offers a 99.999% uptime SLA for its users.	Socket.IO No It is a library, not a platform.	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.	PubNub Yes	Socket.IO No	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.	PubNub Yes PubNub supports multi-region data replication across different points of presence except for file sharing. Read more	Socket.IO No	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.	PubNub No	Socket.IO No As Socket.IO is a library, the implementation of it dictates points of failure and 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.
Latency	Low latency is crucial for realtime apps as it ensures swift and efficient data transmissions, providing a smoother and more responsive user experience.	PubNub <100 milliseconds delivery.	Socket.IO Unknown	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.	PubNub Yes	Socket.IO No	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.	PubNub Yes	Socket.IO No No native Token based auth. It is possible to use middlewares.	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.	PubNub Yes PubNub implements SAML SSO authentication.	Socket.IO No No native SSO. It is possible to use middlewares.	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.	PubNub Yes PubNub supports rules for permissions and operations through its Access Manager. See Access Manager docs	Socket.IO No	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.	PubNub Yes PubNub uses AES256 encryption for end-to-end encryption of messages and files. Read more	Socket.IO No	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.	PubNub Yes	Socket.IO No	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.	PubNub PubNub is compliant with five policies for the security and privacy of its services: ISO 27001 SOC 2 Type II HIPAA GDPR CCPA PubNub FAQ page	Socket.IO None.	Compliance with regulations can impact your ability to meet legal obligations in your industry.