A realtime chat API handles the hard parts of live messaging, delivering messages instantly, showing who's online and keeping history, so you don't build them on raw sockets. Decide first whether you want a hosted chat product with UI kits, a pub/sub network you build chat on, or a server you host yourself, because that choice narrows the field fast.
Two of the nine options on this page don't host anything for you at all: one is a messaging server you run on your own machines and the other is an open-source library you build on. The other seven are hosted, and even they split into finished chat products and lower-level realtime networks. That spread is why chat vendor comparisons so often go sideways. The nine below are listed in no particular order, for developers and technical founders adding live messaging to an app.
What to settle before you compare vendors
Most of the decision is made before you open a single vendor demo. Write down your answers to these and half the list will fall away on its own:
- Who sees the chat: customers talking to each other, customers talking to your team, or staff talking among themselves.
- Whether you want ready-made chat screens or you'd rather design every bubble and input yourself.
- Which platforms you ship on, such as web, iOS, Android or a cross-platform framework, and whether each has an SDK.
- How long message history must be kept, and who's allowed to read it later.
- What moderation you'll need on day one, from blocking users to filtering content.
- Whether chat is the only live feature, or whether presence, live cursors or notifications ride on the same connection.
- Whether your security review allows a third party to hold message data at all, or wants everything on your own servers.
Those answers point you at a kind of product before they point you at a vendor. A support chat on a booking app needs very different things from an internal team chat or a game lobby.
Three ways to get live messaging into an app
Hosted chat products with SDKs and UI
These give you channels, history and moderation as a service, usually with ready-made screens. Stream Chat sells its chat API alongside video, activity feeds and moderation, which matters if you'll want those later. Ably Chat lists reactions, occupancy, edits, deletes and pluggable moderation. CometChat pairs chat with calling, UI kits and an on-prem option, and TalkJS leans into a drop-in chatbox for websites and apps. The enterprise vendor in this group now presents chat as one part of a communications API covering voice and video too.
Realtime networks you build chat on
PubNub offers a chat solution on top of a broader realtime platform that also carries event and device messages. The pub/sub channels service on the list works at a lower level again: channels, presence and webhooks, with the chat logic left to you. These suit teams whose app has several live features and who want one connection layer for all of them.
Software you run yourself
Centrifugo is a real-time messaging server you deploy and publish to through an API. Socket.IO is a library for two-way, low-latency communication between browser and server, a building block rather than a chat product. Both keep message data on your own infrastructure, and both leave history, moderation and screens for your team to build.
Who owns your chat stack now
Chat vendors don't stand still, and two of the long-standing names show it. Pusher's own Channels page says it became part of MessageBird back in 2020. The enterprise chat vendor in this list now leads its homepage with an AI customer experience platform, with the chat API sitting under its communications API. Neither change means the product has stopped working, but it does tell you where each company's attention is going, and that shapes what gets built next.
So the first thing to test isn't a feature. Read the vendor's current homepage and product page, not a comparison you saved two years ago, and check that the product you need is still the one being described. Then look at how you'd leave: whether you can export message history in a format you can load elsewhere, and how much of your app's code would be tied to their SDK. The two self-hosted options avoid that question entirely, in exchange for running the servers yourself.
The nine side by side
| Tool | Kind of tool | Who it suits |
|---|---|---|
| Ably Chat | Realtime platform chat API | Chat features without building them |
| Centrifugo | Self-hosted realtime server | Teams running their own messaging server |
| CometChat | Chat SDK, UI kits and API | Chat and calling with ready-made UI |
| PubNub | Realtime messaging network with chat | In-app chat next to device and event messaging |
| Pusher Channels | Pub/sub realtime channels | Presence and live features on web and mobile |
| Sendbird | Enterprise chat and calls API | Enterprise chat, voice and video |
| Socket.IO | Open-source realtime library | Developers building chat from scratch |
| Stream Chat | Hosted chat API and SDKs | In-app messaging with feeds and video nearby |
| TalkJS | Drop-in chat UI and API | A ready chatbox on a website or app |
Each option in brief
Alphabetical, one line each from how the vendor describes its own product.
Ably Chat
Best for: Apps needing one-to-one and group chat with reactions, occupancy, edit and delete, and pluggable moderation; the vendor bills it as built for serious scale.
Centrifugo
Best for: Teams happy to run their own real-time messaging server, written in Go, and publish to it through a simple API, with a PRO edition available.
CometChat
Best for: Products wanting chat and calling with UI kits and moderation, plus an AI agent platform and an on-prem deployment option, per the vendor.
PubNub
Best for: Apps where chat sits beside other realtime traffic, since the vendor's platform also covers event and device messaging use cases.
Pusher Channels
Best for: Adding live features to web and mobile apps through pub/sub channels, with presence channels for user lists, webhooks and a queryable API.
Sendbird
Best for: Larger companies after a communications API for chat, voice and video, which the vendor now places inside a wider AI customer experience platform.
Socket.IO
Best for: Developers who'd rather build chat themselves on an open-source library for two-way, low-latency communication between browser and server.
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Stream Chat
Best for: Hosted in-app messaging through an API and SDKs, sold alongside the vendor's video, activity feed and moderation products.
TalkJS
Best for: Private and group conversations through a drop-in chatbox, with an AI support agent add-on, for teams who don't want to design chat UI.
Send one message through two of them
A chat API can look identical in two demos and feel completely different in your app. Give your two strongest candidates the same small task:
- Create two test users and a group channel with a third, the way your app would.
- Send messages from a phone on a weak connection and a laptop at the same time, and watch the order they arrive in.
- Close the app mid-conversation, reopen it, and check that history and unread counts come back as you'd expect.
- Delete a message and block a user, then see what everyone else in the channel sees.
- Export the conversation and check you can read it without the vendor's dashboard.
Whichever one gets through that with the least custom code is the one worth building a prototype on.
Before your first release
My advice is to keep your own thin layer between your app and the chat provider, even if it's only a handful of functions for sending, loading and moderating messages. It takes a day now and saves a rewrite if you ever move. Start with the hosted chat products if chat is the feature and your team is small, and with a realtime network or your own server if live updates run through the whole app.
If you're replacing an existing provider rather than starting fresh, my lists of Pusher alternatives and Sendbird alternatives go deeper on each move.
Do you make a chat API, realtime messaging service or chat SDK? Tool makers can ask to be considered for a featured place on this list.
Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.
Frequently asked questions
What's the difference between a chat API and a pub/sub service?
A chat API gives you chat concepts out of the box, such as channels, history and moderation. A pub/sub service delivers messages on channels in real time and leaves the chat features for you to build.
Can I host a chat backend myself?
Yes. Two options on this list run on your own infrastructure: a messaging server you deploy and an open-source library you build on. You'll own history, moderation and scaling, so plan the engineering time.
Do I need ready-made chat UI?
Not always. Ready-made screens get a first version live quickly, while building your own gives full control over the design. Some vendors here offer UI kits or a drop-in chatbox alongside the API.
Are any of these free to start with?
A couple state a free plan on their own sites and one offers a trial. What's included can change, so check each vendor's website before you build on it.
How should I handle moderation in a chat app?
Decide what you need before launch, from blocking users to filtering messages, and check whether each provider offers it or leaves it to your code. Moderation added after launch is usually harder.
Can chat and other live features share one connection?
With the realtime networks, usually yes, since chat is just one kind of channel traffic. Hosted chat products focus on chat itself, so check how they handle presence, notifications or live updates elsewhere in your app.
