WebSocket alternatives: Exploring realtime protocols

SSE is a unidirectional protocol that allows servers to push updates to the client over a single long-lived HTTP connection using the text/event-stream MIME type.

Pros:

• Easy to implement

• Native support in modern browsers

• Built-in reconnection support

Cons:

• Only supports server-to-client communication

• Not suitable for use cases that require bi-directional messaging

• Limited browser support on Internet Explorer and some older platforms

Ideal for: Live newsfeeds, real-time dashboards, notifications

See how SSE compares to WebSocket

Long polling emulates realtime communication by having the client repeatedly request updates from the server. The server holds the connection open until new data is available then the client immediately opens a new request.

Pros:

• Works everywhere (broad compatibility)

• Easy to implement using standard HTTP infrastructure

Cons:

• Higher latency and network overhead

• Doesn’t scale efficiently for high-throughput apps

• Can be more taxing on servers under heavy load

Ideal for: Legacy systems or environments with limited protocol support

See how long polling compares to WebSocket

MQTT (Message Queuing Telemetry Transport) is a lightweight, publish-subscribe protocol for constrained devices and low-bandwidth networks.

Pros:

• Very low overhead — ideal for IoT

• Supports retained messages, last-will messages and QoS guarantees

• Efficient for mobile and embedded environments

Cons:

• Not natively supported in browsers (requires additional tooling)

• More common in backend and device-client use cases

• Limited payload size and features compared to full protocols

Ideal for: IoT, telemetry, sensor networks, mobile apps in unreliable networks

See how MQTT compares to WebSocket

WebTransport is a newer protocol that allows multiplexed, bi-directional communication over HTTP/3. It aims to address many of the use cases currently covered by WebSockets, with better transport-level capabilities.

Pros:

• Built on HTTP/3 and QUIC — supports multiplexing and lower handshake overhead

• Better reliability and congestion control

Cons:

• Still experimental (as of 2025), limited browser and server support

• Complex to implement and troubleshoot

Ideal for: High-performance, modern web apps — once support matures

Learn more about WebTransport

Overview:
gRPC supports bi-directional streaming using HTTP/2, typically for communication between backend services. It’s efficient, strongly typed and integrates well into polyglot microservice ecosystems.

Pros:

• Great for internal backend systems

• Supports multiplexing and streaming via HTTP/2

• Language-agnostic and auto-generates client/server code

Cons:

• Not suitable for browser-based real-time use cases

• Steeper learning curve and infrastructure complexity

• More focused on RPC patterns than messaging

Ideal for: Backend microservices, realtime APIs within distributed systems

See how gRPC compares to WebSocket

WebSockets are powerful but different protocols offer tradeoffs for different environments or requirements:

• SSE is simpler and better when you only need server-to-client.

• Long polling is useful in legacy systems where newer protocols aren’t supported.

• MQTT is great for constrained or low-bandwidth environments like IoT.

• WebTransport is promising for high-performance browser apps as HTTP/3 adoption grows.

• gRPC is good for backend-to-backend streaming.

Sometimes you don’t need to replace WebSockets entirely but rather supplement them with fallback protocols to improve resilience or compatibility - or use them in combination.

For example, if you’re developing a video conferencing solution, WebRTC is a great option for sending audio and video data between peers. In this scenario, WebSocket complements WebRTC, and is frequently used as a signalling mechanism for WebRTC peers.

Another example: due to its lightweight design, MQTT is an excellent choice for collecting telemetry data from IoT sensors. However, if you want to use this data to power realtime dashboards that can be monitored in a browser, MQTT is unsuitable, as it’s not supported in browsers. What you can do is send the data to browsers over WebSockets. That’s why many MQTT brokers nowadays also support WebSockets (or MQTT over WebSockets).

Choosing a protocol is just the start. Building a robust realtime experience also means solving for:

• Message delivery guarantees and ordering

• Auto-reconnect and connection state tracking

• Presence and occupancy awareness

• Message history and replay

• Load balancing and global scalability

• Observability and failure handling

These concerns often force engineering teams to build additional infrastructure around low-level protocols as the application grows.

Ably is a realtime platform that provides reliable, low-latency messaging using WebSockets by default, with intelligent fallbacks to HTTP-based transports when needed. From a developer’s perspective, Ably offers a consistent API and a global edge network that ensures message delivery, ordering, and client connection state tracking across regions.

Rather than replacing WebSockets, Ably helps developers scale beyond them—eliminating the need to manage protocol behavior, build reconnection logic, or worry about infrastructure overhead.

Explore how Ably compares to working directly with WebSockets

Explore Ably docs