SignalR vs. gRPC in ASP.NET Core: Which to Choose - Programmer Scientist (2023)

My book,SignalR in .NET 6: The Complete Guide, Now available! also availablein print.

Some time ago, even before ASP.NET Core existed, Microsoft created a library for ASP.NET based on the .NET Framework, which allows real-time bidirectional communication between clients and a server. This library was called SignalR.

The purpose of this library was to greatly simplify the implementation of the standard communication protocols normally used for this type of communication. These records containWebSocket,long votejevents sent by the server.

Each of these protocols could be used directly, but none of them were very easy to use alone. SingnalR made it easy by hiding all the complex implementation details.

With the arrival of ASP.NET Core version 2.1, this library was completely rewritten and became astandard piecedo ASP.NET Core.

gRPCis a communication protocol originally developed by Google. Unlike SignalR, it does not leverage the use of existing protocols. It is a fully autonomous protocol that takes advantage of the new properties ofHTTP/2, which opened to the public in 2015.

gRPC implementations are available in most major programming languages. And since ASP.NET Core 3.0 was released, it has become acomponentof ASP.NET Core, just like SignalR before it.

Both technologies are extremely useful and can be used for similar purposes. Whether one is better than the other just depends on the context.

Today we'll look at the pros and cons of each of these technologies in different contexts so you're better equipped to decide which ones to use.

(Video) Choosing the correct Communication Protocol : REST vs SignalR vs gRPC vs GraphQL

Where SignalR beats gRPC

I previously sketched the keyBenefits of using SignalRcompared to handwriting equivalent functions. These can be summarized as follows:

  • All complexity is abstracted
  • No more need for AJAX
  • Works with any type of client (even pure WebSocket clients)
  • It scales very easily
  • Used by default in many parts of ASP.NET (for example, inBlazor-Server)

The most fundamental benefit of using SignalR is how it abstracts away complex WebSocket implementations, time-consuming lookups, and server-side events. For example, while a pure WebSocket implementation might look like this:

SignalR vs. gRPC in ASP.NET Core: Which to Choose - Programmer Scientist (1)

The SignalR equivalent looks like this:

SignalR vs. gRPC in ASP.NET Core: Which to Choose - Programmer Scientist (2)

This time, however, we are not comparing SignalR with manually creating your own implementations. We specifically compare it to gRPC. So here are some of the advantages SignalR has over gRPC:

1. No need to use HTTP/2 (meaning it works pretty much anywhere)

Without HTTP/2 there is no gRPC. This means that not all systems can use it. If the client or server application you're working on is hosted on a system that doesn't support HTTP/2, there's nothing you can do to make it work.

SignalR, on the other hand, works with plain HTTP. That's why it can be used on almost all systems.

Of course, not all systems can use the WebSocket protocol. As a result, you may not be able to use SignalR most efficiently in some configurations. But that's exactly why you have two alternative logs: server-sent events and long queries.

And just because SignalR doesn't use HTTP/2 doesn't mean it's less powerful than gRPC. Yes, HTTP/2 offers many performance benefits such as: B. Compressed headers that improve performance. And the messaging mechanism used by gRPCbuffer de log, efficiently serializes messages, making the payload as small as possible, further increasing performance.

However, when used with WebSocket, SignalR is comparable in efficiency. First, it only uses the HTTP header to make the initial connection, so the header compression provided by HTTP/2 is almost irrelevant. Second, it can be configured to use a proprietary binary JSON protocol calledmessage packet, which, like the log buffer, significantly reduces the payload size, thereby improving performance.

(Video) Using SignalR and ASP.NET Core for real-time communication

In terms of performance, SignalR and gRPC are comparable. And both outperformed standard HTTP-based communications.

2. Events can be initiated from a client or server

A limitation of gRPC is that it remains very similar to a standard request-response model used by HTTP. Only the client can initiate events. The server can only respond to these.

There is a solution. gRPC can useStreaming-Server, where the client sends the initial request and both the client and the server keep the stream open, allowing the server to send messages when a specific action is triggered.

But implementing that would have to be pretty clunky. Broadcast calls are not intended for this use. You have to add client and server loops and manually manage the connection state. Also, you should do this for every single method that needs to communicate in both directions.

With SignalR, on the other hand, you only need to send the client's first connection request. After that, both client and server can send messages to each other through any terminal. All you need to do is add methods on the server side and named event listeners on the client side. The connection can remain open indefinitely. SignalR's own library manages the connection status for you, sending heartbeats at regular intervals and automatically trying to reconnect if the connection is lost.

And like gRPC, SignalR is fully capableReal-time data transferBoth to and from the server.

3. No need to write communication contracts and generate code from them.

To enable gRPC communication, you must write aprototype filewould contain the definitions of the gRPC services and any remote procedures in those services that clients might call. Once that's done, you need to run a language-specific tool to generate code that conforms to those definitions. And only then can you start writing real logic.

With SignalR, you don't have to do any of that. All you have to do is write any method definitions in your server-side application and write named message handlers in your client.

Of course, this doesn't come without its own potential problems. For example, you must be very careful that method names are spelled the same on both the client and the server. However, because there's no need to write an explicitly defined contract, and there's no need to rely on multiple tools to generate code based on that contract, the development process is significantly accelerated.

(Video) Streaming three ways with Blazor: REST, gRPC, and SignalR - Carl Franklin - NDC Porto 2022

Where gRPC trumps SignalR

While SignalR has its advantages over gRPC, the latter would be a better solution in certain situations. Here are areas where gRPC has an advantage over SignalR.

1. Much easier API versioning

While using gRPC requires you to write an explicit contract between the client and server, this isn't always a disadvantage. For example, the way the prototype format was designed allows you to easily apply API versioning.

When defining a message structure in a proto file, you must assign a unique integer to each of its fields. That would look like this:

SignalR vs. gRPC in ASP.NET Core: Which to Choose - Programmer Scientist (3)

And this mechanism facilitates API versioning. Let's imagine a scenario that will help us understand why this happens.

In the first version of the gRPC service, you have a message definition that contains two fields as in the screenshot above: "request_id" and "payload_collection". Numbers 1 and 2 are assigned to these fields. Now, for our second version, we decided to add a new field, a timestamp, and assign it the number 3.

As long as we haven't changed any of the existing number fields, customers who haven't received this update will continue to work with the new message definition. If it is a response object definition that the server returns to the client, the client simply ignores the new field, as a field numbered 3 is not described in its own prototype definition. If it were a request object, the client would fill in the first two fields and field number 3 would be given a default value on the server side.

In both cases, client and server continue to function. The key is not to change fields with existing numbers. Otherwise things can break.

SignalR has none of that. Of course, nothing prevents you from implementing your own API versioning mechanism similar to this one. But with gRPC you already have this engine, so there's no need to reinvent the wheel.

2. Libraries available in virtually every language

Although SignalR is open source, it is still a Microsoft proprietary technology. And that's why SignalR Server can only be written in Microsoft's own backend languages ​​(but mostly C#).The use of F# is also supported).

(Video) Why would I use SignalR over calling WebSockets directly?

SignalR clients can also only be written in a limited number of languages. At the time of writing, only .NET, JavaScript and Javaclientelethey were supported. Of course, you can write your own client in any language with pure WebSocket, but you'll lose all the benefits of using SignalR if you choose that method.

gRPC, on the other hand, is an open standard. And that's why it's available atmany popular languages🇧🇷 This applies to both the client and the server.

3. Easier to use in microservices architecture

Another area where gRPC excels in SignalR is communication betweenmicrosserviçosjcontainer.

More and more companies are eliminating large monolithic applications, breaking them down into smaller components that can be run and updated individually. However, these components still form a large distributed application. And therefore there must be an efficient mechanism for them to communicate with each other.

Various forms of remote procedure call (RPC) mechanisms have traditionally been used for this purpose. They tend to be more efficient than HTTP because they don't contain as much data in the headers. Also, they don't have to adhere to outdated common standards and can be completely proprietary.Azure Service Fabric-RemotingThe mechanism is an example of this.

gRPC eliminated the need to use proprietary RPC mechanisms for different types of technologies. It's an open standard, so any system can use it. And it's very efficient because it runs on HTTP/2.

SignalR, on the other hand, would not be efficient enough to make microservices communicate with each other. While it allows you to write code that makes it appear as if the client and server are calling each other's methods remotely, this isn't really happening under the hood. Instead, a persistent connection is established between the client and the server. And the connection is maintained by sending small heartbeat messages in both directions.

If you have a distributed application with a large number of moving parts, imagine how much bandwidth would be used if all the individual components opened up a series of persistent connections to communicate with each other. With gRPC, on the other hand, data is exchanged only when such an exchange is required. The only time you need a persistent connection is when using Streams. But even then it would close the stream after transmitting all the data.


Both SignalR and gRPC are excellent communication mechanisms that every Microsoft software developer should learn. And none is better than the other. There are only a few scenarios that favor using a particular one.

(Video) WebAPI vs gRPC : Carl Franklin's Blazor Train Ep 45

For example, if you need to build something where the server communicates with the client on a regular basis, SignalR would be better. On the other hand, if you are building a large distributed application with many moving parts, gRPC would be a better mechanism for these parts to communicate with each other.

PS: If you want to know more about SignalR, you can check out my bookSignalR in .NET 6: The Complete Guide.


Can gRPC replace SignalR? ›

For example, if you need to build something where the server regularly communicates with the client, SignalR would be better. If, on the other hand, you are building a large distributed application with many moving parts, gRPC would be a better mechanism for those parts to communicate with one another.

What is better than SignalR? ›

There are many alternatives for signalR that are used, like Firebase, pusher, webRTC, RabbitMQ, gRPC, and MQTT.

Do people still use SignalR? ›

SignalR is relevant for now, it supports mobile devices, and many other things. SignalR is the same WebSocket but with many ready stuff. You can use raw WebSocket instead of it, but you will have to do many things to gain what you want. So SignalR is more easy to use.

Is SignalR obsolete? ›

Differences between SignalR and ASP.NET Core SignalR | Microsoft Learn. This browser is no longer supported. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.

What are the disadvantages of gRPC? ›

Weaknesses of gRPC

As gRPC heavily uses HTTP/2, it is impossible to call a gRPC service from a web browser directly. No modern browser provides the control needed over web requests to support a gRPC client. Therefore, a proxy layer and gRPC-web are required to perform conversions between HTTP/1.1 and HTTP/2.

When should I use SignalR? ›

SignalR can be used to add any sort of "real-time" web functionality to your ASP.NET application. While chat is often used as an example, you can do a whole lot more. Any time a user refreshes a web page to see new data, or the page implements long polling to retrieve new data, it is a candidate for using SignalR.

How many clients can SignalR handle? ›

IIS on client operating systems has a limit of 10 concurrent connections. SignalR's connections are: Transient and frequently re-established. Not disposed immediately when no longer used.

Is SignalR better than WebSocket? ›

On the other hand, for more complex use cases, such as a production-ready chat app, SignalR is a superior alternative, as it allows you to move faster than plain WebSockets, and provides features like automatic reconnections and the ability to broadcast messages to multiple clients (useful for multi-user chat).

Does Whatsapp use SignalR? ›

This is how Whatsapp works. Thus, you may have got that - Whatsapp is a client, who needs a Server to send the message. Thus, the first thing that we need is a chat Server. Thus, we will use Signalr to create the server.

How long does a SignalR connection last? ›

The default keepalive timeout period is currently 20 seconds. If your client code tries to call a Hub method while SignalR is in reconnecting mode, SignalR will try to send the command.

Does SignalR guarantee delivery? ›

SignalR doesn't guarantee message delivery. Since SignalR doesn't block when you call client methods, you can invoke client methods very quickly as you've discovered.

Is SignalR a TCP or UDP? ›

SignalR is more closely aligned to the UDP pattern of communication, and not TCP.

Is SignalR a REST API? ›

Azure SignalR Service provides REST API to support server to client communication scenarios, such as broadcasting. You can choose any programming language that can make REST API call. You can post messages to all connected clients, a specific client by name, or a group of clients.

Is SignalR two way communication? ›

Two-way communication means that both the server and client share an open channel in which they can initiate contact with each other. This channel is high-speed and works both directions between server and client. Many kinds of software can benefit from the real-time, two-way, communication system of SignalR.

When should you not use gRPC? ›

If you know that a significant amount of your API consumers will not be able to use native gRPC libraries, it's probably not the best tool to use. Also, if you're building like one of APIs that you know you will sunset soon, for example, you build migration APIs or something, the schema overhead might not be worth it.

Is gRPC outdated? ›

No, Grpc. Core will continue to be supported for a while (see the deprecation schedule). There should be enough time for you to assess the situation and plan your migration.

Is gRPC faster than REST? ›

“gRPC is roughly 7 times faster than REST when receiving data & roughly 10 times faster than REST when sending data for this specific payload. This is mainly due to the tight packing of the Protocol Buffers and the use of HTTP/2 by gRPC.”

Is SignalR long polling? ›

SignalR is a Microsoft framework specifically designed to facilitate real-time client/server communication. It provides an effective implementation of long polling that doesn't have a deep impact on the server, and at the same time ensures that clients are appropriately updated about what's going on remotely.

Does SignalR use WebSockets? ›

ASP.NET Core SignalR is a library that simplifies adding real-time web functionality to apps. It uses WebSockets whenever possible. For most applications, we recommend SignalR rather than raw WebSockets.

Does SignalR need SSL? ›

If your SignalR application transmits sensitive information between the client and server, use SSL for the transport.

How many groups can SignalR handle? ›

So if your SignalR service can handle 40k+ users, it will handle 40k+ groups.

Is SignalR full duplex? ›

SignalR supports full duplex communication that allows the client and server to transfer data back and forth.

Can SignalR stream video? ›

ASP.NET Core SignalR supports streaming from client to server and from server to client.

Is gRPC better than WebSocket? ›

gRPC is preferred over WebSockets if the application demands various requests processing at one time. gRPC supports multiplexing that arranges different requests seamlessly. But, multiplexing isn't offered by WebSocket. Hence, one connection is useful only for one request.

What will replace WebSockets? ›

WebTransport is a new specification offering an alternative to WebSockets. For applications that need low-latency, event-driven communication between endpoints, WebSockets has been the go-to choice, but WebTransport may change that.

Does gRPC use WebSockets? ›

Using the Library in Your Server Code

However, it's important to note that if the user wishes to use WebSockets, then the downgrading handler must be used, as traditional gRPC servers do not support WebSockets.

How can I improve my SignalR performance? ›

Reducing message size

Names can be shortened in messages from the client to the server as well, using the same method. Reducing the memory footprint (that is, the amount of memory used for the message) of the message object can also improve performance.

Which protocol is used by SignalR? ›

SignalR provides two built-in hub protocols: a text protocol based on JSON and a binary protocol based on MessagePack. MessagePack generally creates smaller messages compared to JSON. Older browsers must support XHR level 2 to provide MessagePack protocol support.

Does AWS support SignalR? ›

Azure SignalR Service doesn't have in-built support for other serverless platforms, such as AWS Lambda or Google Cloud Functions. Which popular services & systems are Amazon API Gateway and Azure SignalR Service integrated with?

Why Signal is not better than WhatsApp? ›

WhatsApp does not protect metadata. This means third parties may see information about the messages. In contrast, Signal developed a technology for protecting metadata called Sealed Sender. This technology hides information about the sender and the recipient, so even the postage label is unreadable.

Why Signal better than WhatsApp? ›

WhatsApp and Signal both feature end-to-end encryption for their voice, video, and text conversations. While Signal hides the metadata of its encrypted messages, WhatsApp does not. Signal is also arguably safer because the app is owned by a nonprofit; WhatsApp is owned by Meta.

Is Signal safer then WhatsApp? ›

Signal is more secure since the app provides end-to-end encryption by default and the company does not keep records of your communications. While messages on WhatsApp are also secure and end-to-end encryption is on by default.

What is forever frame in SignalR? ›

foreverFrame works a bit like serverSentEvents - there is one long running http request which the server never terminates but uses to push data to the client.

Does SignalR work on mobile? ›

NET client runs on any platform supported by ASP.NET Core. For example, Xamarin developers can use SignalR for building Android apps using Xamarin. Android 8.4. 0.1 and later and iOS apps using Xamarin.

How to keep session alive in ASP.NET c#? ›

Solution 1

Place a timer on the ASP.NET page, set the interval time, i.e. 1 minute. and add UpdatePanel to handle the timer1 tick event asynchronously. at the code behind, inside the timer's tick event, you do nothing. once the timer1 raises the tick event, the session time out is reset and kept alive.

Why use Azure SignalR? ›

Azure SignalR Service simplifies the process of adding real-time web functionality to applications over HTTP. This real-time functionality allows the service to push content updates to connected clients, such as a single page web or mobile application.

Who is the creator of SignalR? ›

Original author(s)David Fowler and Damian Edwards
Initial release18 February 2013
Stable release2.4.1 / April 2, 2019
8 more rows

How do you send a notification in SignalR? ›

You can code a SignalR hub and configure a communication endpoint to connect with your apps using client libraries. First, create a hub or class for persistent connections (invocation model) between server and client. Then, create a subscription to the hub method and a code to invoke a hub method to send messages.

Does SignalR use JSON? ›

ASP.NET Core SignalR supports two protocols for encoding messages: JSON and MessagePack.

Is Netflix traffic UDP or TCP? ›

Netflix uses TCP because TCP is much time-sensitive and does not require port forwarding. It helps to enable the full bandwidth of the network.

Does SignalR need server? ›

Supported server operating systems

Note that for SignalR to use WebSockets, Windows Server 2012, Windows Server 2016, or Windows 8 is required (WebSocket can be used on Windows Azure Web Sites, as long as the site's . NET framework version is set to 4.5, and Web Sockets is enabled in the site's Configuration page).

Do banks use REST API? ›

Representational state transfer or REST services are one way to architect APIs and the most common ways to define and implement them in Open Banking. REST focuses on resources and their state. In our context, a resource can be a bank account and its state may be the balance.

How to use SignalR in asp net core Web API? ›

NET Core Web API application.
  1. Configure your project.
  2. Provide some additional information about your project.
  3. Install SignalR NuGet package.
  4. Project Structure:
  5. Create IMessageHubClient. cs class inside the Hub Folder. namespace SignalRDemo. ...
  6. Again, open the client application window. You will see the offer message.
25 Jul 2022

Does SignalR use Redis? ›

It also supports a messaging system with a publish/subscribe model. The SignalR Redis backplane uses the pub/sub feature to forward messages to other servers. For this tutorial, you will use three servers: Two servers running Windows, which you will use to deploy a SignalR application.

Which asp net core no longer depends on the system? ›

Fast: ASP.NET Core no longer depends on System. Web. dll for browser-server communication. ASP.NET Core allows us to include packages that we need for our application.

What is the difference between SignalR and WebSockets? ›

WebSockets is actually the underlying transport that SignalR uses, at least most of the time. SignalR has the ability to fall back to other ways of transporting messages, such as long-polling over HTTP. This is useful in situations where you don't have WebSockets support.

Does SignalR work with HTTP? ›

SignalR includes automatic connection management, it provides the facility to broadcast messages to all connected clients or to a specific client. The connection between the client and server is persistent while in HTTP it isn't persistent.

What is the alternative of gRPC? ›

GraphQL, RabbitMQ, Kafka, REST, and MQTT are the most popular alternatives and competitors to gRPC.

Is gRPC deprecated? ›

gRPC C-core is in maintenance mode and will be deprecated in favor of gRPC for . NET. gRPC C-core is not recommended for new apps.

Is gRPC good for frontend? ›

It is a great technology, especially if you are already using gRPC everywhere. We're using it with great success in our frontend application. If you're interested in learning more, you can get started with the source code for this article here.

Is gRPC replacing REST? ›

No, you don't need to switch from REST

gRPC is not the evolution of REST, nor is it a better way to build APIs. In a nutshell, gRPC is a way to use RPC's lightweight structure along with HTTP with a few handy tweaks. It's just another alternative for you to consider when you start designing a new API.

Is gRPC a Layer 7? ›

gRPC is at OSI layer 7 — an RPC layer built on top of HTTP/2.

Why not to use gRPC? ›

As CircleCI reports, gRPC can also be fragile and more complex than the alternatives. Thus, it's not always the best solution for every problem in which the need for high-speed communication over a network is a critical factor.

Is gRPC the future? ›

It's not the future, and it's not gonna kill REST. gRPC is a tool in a large toolbox. gRPC can have a niche, but that niche is internal communications. gRPC cannot and should not replace REST for external APIs any time soon.

Does Google use gRPC? ›

How Google uses gRPC. gRPC is being used for communication in internal production, on Google Cloud Platform, and in public-facing APIs.

Why gRPC is better than REST in microservices? ›

REST APIs generally use JSON or XML message formats, while gRPC uses protocol buffers. To signal errors, REST APIs use HTTP status codes, while gRPC uses error codes. gRPC's message sizes tend to be dramatically smaller than those of REST APIs.

Is gRPC more secure than REST? ›

Both gRPC and REST communications are secured with TLS/SSL. Streaming is bidirectional in gRPC, while only 1 way request from client to server in REST. So gRPC is better than REST for most of the things that we've mentioned so far.

Is gRPC faster than socket? ›

gRPC provides 2 ways of communication i.e. Blocking and Non-Blocking. gRPC using Non Blocking Socket gives the best performance. Conclusion: Performance of gRPC is almost 3 times better than that of REST API.

Can gRPC call REST API? ›

Yes, it is possible. You can make calls to other APIs and services from your own gRPC service code. Just let your client make a call to your gRPC service. Then, your service makes a REST call to external API (possibly using arguments from client request to your gRPC service) and processes it.

Why gRPC is not supported in browser? ›

It's not possible to directly call a gRPC service from a browser. gRPC uses HTTP/2 features, and no browser provides the level of control required over web requests to support a gRPC client. gRPC on ASP.NET Core offers two browser-compatible solutions, gRPC-Web and gRPC JSON transcoding.

Is gRPC a TCP or HTTP? ›

gRPC uses HTTP/2, which multiplexes multiple calls on a single TCP connection. All gRPC calls over that connection go to one endpoint.


1. 1 - Introduction to gRPC - ASP.NET Core | Programming in gRPC
2. What is SignalR and how does it aid with real-time communication on the web?
(Microsoft Developer)
3. ASP.NET Core Series: SignalR
4. Synchronizing Data with SignalR: Carl Franklin's Blazor Train ep 30
5. Embracing gRPC in .NET - Irina Scurtu - NDC Porto 2022
(NDC Conferences)
6. ASP.NET Core Series: High performance requests with gRPC


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