Chatto is now Open Source

> It’s designed to be extremely easy to self-host on your own infrastructure.

Kudos for this. Per the docs: https://docs.chatto.run/,

> Chatto ships in a compact, self-contained binary

> it uses NATS, a compact message broker that also ships with a built-in stream persistence engine [...] NATS is just as easy to provision as Chatto, and most of our examples will show you how.

> you can also configure an external S3-compatible object storage for Chatto to store your files in, and we strongly recommend doing so...

> The actual calls are powered by LiveKit (Apache-2.0), which you need to deploy alongside Chatto. As with NATS, the deployment examples show the required wiring.

> ...

And kudos for backing it up with real guidance. Great project.

I’ve known Hendrik for years, and he is one of the most talented developers I’ve ever met. I’m confident this project will become successful very quickly. Beyond the project itself, what fascinates me most is how he single-handedly developed it by leveraging agentic coding.

This is awesome! Some feedback - I can't tell anywhere from the website if there is mobile support (which is a must-have if I want to consider moving my company or friends over to this)

> And it’s really good hosting! Chatto Cloud is launching with fully European and European-owned infrastructure, with more regions slated for launch in early 2027

With chat control that may not be so great…

Couldn't help but smile because "chato" in portuguese means "boring", and this seems very easy to set up and use.

Here's to more boring software! :)

What's the rationale for the dual licensing? It looks like the Go backend is AGPL but the TypeScript frontend is Apache 2.0.

Why not keep it all AGPL?

Very cool. I don't usually get excited for new chat apps, but I like the idea of having one frontend for multiple servers instead of pushing hard on p2p or federation.

I do also still like irc, but haven't used it much in recent years because most of the people I talk to are using discord now.

Saw so many open source chats happen behind (or "in") Discord. Will this allow community members to drop in and chat and Google the contents?

The fundamental problem with replacing Slack is network effects. Your coworkers and customers already use Slack. It works well enough.

You can choose to switch your company away, maybe, but what do you do when vendors want to connect over Slack?

Imagine if email was owned by a company?

Edit:

W̶e̶ ̶r̶e̶a̶l̶l̶y̶ ̶n̶e̶e̶d̶ ̶a̶n̶ ̶o̶p̶e̶n̶ ̶p̶r̶o̶t̶o̶c̶o̶l̶ ̶t̶o̶ ̶b̶u̶i̶l̶d̶ ̶o̶n̶.̶

We really need an open protocol to win here.

Not knowing what Chatto is, the headline is giving "zendaya is meechee"

Looks great! How does it compare to Zulip? we self host zulip and are quite happy with it

So encrypted at rest but no E2EE, did I read that right?

So, an open-source Discord clone?

I mean, people have been asking for alternatives lately, so it's not like there isn't a market for it. There are even entire communities[0] for discovering them.

But considering there are already several dozen alternatives: what makes this one special? What sets it apart from Gamevox, Cinny, Element, Schildi, Echon, Neremity, Fluxer, Faction, Stoat, Guilded, Root, Loqa, Venta, Osmium, and so on and so on? Heck, a handful of vibecoded new ones spring up every week!

If you're going to release Yet Another Clone, you have to make it immediately obvious 1) how it compares feature-wise, and 2) what unique thing makes yours special enough to overcome the extremely powerful network effects of the incumbents. Reading this page Chatto looks neat I guess, but there's nothing convincing me to invest several hours into discovering whether this is truly a Discord killer, or Yet Another Clone. Same with the official website and docs: some techy mumbo-jumbo, but that's about it.

No matter how impressive it is technically and no matter how free and open it may be, without significantly better marketing material it'll have a chance at becoming relevant.

[0]: https://www.reddit.com/r/DiscordAlternatives/

Looks great - is there any info on what server resources are actually required per feature or user count?

This is cool. Will try out soon.

Love that the way you said the rhymes part 'rhymes with “knack”, or the one that rhymes with “beams”, or the one that rhymes with “this gourd”'.

Looks really nice, thank you for open-sourcing. I keep a directory of opensource alternatives. Would you say this is a Discord or Slack alternative?

Super happy to see someone take on slack. We just want a performant chat with simple features.

Slack integrations are overrated. Just give me webhooks.

Would English speakers pronounce this as "Chat-to"? To a Japanese person, this clearly sounds like "Cha-tto," which simply means "chat."

Needs drop in voice rooms a la Discord or Slack's Huddle

I’m wondering about privacy tradeoffs. Looks like they’re similar to Discord where the chats won’t show up in web searches and you can’t read anything without joining. But if anyone can join, it’s not like Signal either and end-to-end encryption wouldn’t make sense.

(They do have end-to-end encryption for video.)

Congrats for open sourcing it, looks interesting!

How does this compare to fluxer.gg though?

The part that I really liked about chatto is that it seems to be made very easily to self host which is something that I really appreciate actually.

Ah mobile app is not ready yet. I am looking for some alternative to matrix because running it with bots is a bit convoluted, i.e. you have to have limit of edits of message for model streaming or you will kill entire room. Or I never seen robots in matrix sending encrypted messages. Why bother than? Anyway if mobile will be a thing this seems like perfect thing to have for your family and friends.

Very cool! You should request being added to https://european-alternatives.eu/

Does this federate with anything, like Matrix or XMPP? If it is locked into a single software, I fear nobody will ever switch to it (I have too many chat apps already!)

Amazing. And with SSO out of the box without weird "Oh, SSO is Enterprise only" BS.

I've been running Mattermost for a couple of years now and I'm content with it. It does feel a little bit clunky sometimes, but it's been stable and performant so I can't really complain. It can also feel a bit much sometimes. A bit too complex. A bit too feature-rich. But if I just ignore most of it, then it's good. I will say that Chatto looks nicer, appears to be simpler to setup and also has simpler licensing. Can it auto-update itself? That's something that's bad with Mattermost.

> And you can just self-host it. For free, too! (A weird thing to write, but the OSS chat app space has become very weird in many ways!)

Wait, what? There are open-source chat apps that you have to pay to host yourself? How does that work? Or did I misunderstand?

> Chatto aims to be the group chat application that you actually enjoy using.

So not like Discord or Slack?

> This is what it looks like:

Discord and Slack?

I mean, OK, it has EU hosting and that is good. But I see nothing obvious here that solves the noise and irritation of Discord and Slack.

soooooo campfire then

> It’s designed to be extremely easy to self-host on your own infrastructure.

Kudos for this. Per the docs: https://docs.chatto.run/,

> Chatto ships in a compact, self-contained binary

> it uses NATS, a compact message broker that also ships with a built-in stream persistence engine [...] NATS is just as easy to provision as Chatto, and most of our examples will show you how.

> you can also configure an external S3-compatible object storage for Chatto to store your files in, and we strongly recommend doing so...

> The actual calls are powered by LiveKit (Apache-2.0), which you need to deploy alongside Chatto. As with NATS, the deployment examples show the required wiring.

> ...

And kudos for backing it up with real guidance. Great project.

This is super cool. More options is always good. Something that is confusing about the docs though... is there a desktop application? The screenshot implies there is but I couldn't find the docs to download THAT.

Can it be installed on Cloudflare or Vercel or something else that is easy/cheap/free?

I second that. I've personally known him for almost 30 years by now, and he's still one of the smartest, most experienced, and most curious devs I've ever met. All around good guy, would work with him again any day of the week.

Alright, I was vaguely interested for a little, but you convinced me to avoid it.

Not knowing what Chatto is, the headline is giving "zendaya is meechee"

Looks great! How does it compare to Zulip? we self host zulip and are quite happy with it

So, an open-source Discord clone?

I mean, people have been asking for alternatives lately, so it's not like there isn't a market for it. There are even entire communities[0] for discovering them.

No matter how impressive it is technically and no matter how free and open it may be, without significantly better marketing material it'll have a chance at becoming relevant.

[0]: https://www.reddit.com/r/DiscordAlternatives/

Looks great - is there any info on what server resources are actually required per feature or user count?

This is cool. Will try out soon.

Love that the way you said the rhymes part 'rhymes with “knack”, or the one that rhymes with “beams”, or the one that rhymes with “this gourd”'.

Super happy to see someone take on slack. We just want a performant chat with simple features.

Slack integrations are overrated. Just give me webhooks.

The fundamental problem with replacing Slack is network effects. Your coworkers and customers already use Slack. It works well enough.

You can choose to switch your company away, maybe, but what do you do when vendors want to connect over Slack?

Imagine if email was owned by a company?

Edit:

W̶e̶ ̶r̶e̶a̶l̶l̶y̶ ̶n̶e̶e̶d̶ ̶a̶n̶ ̶o̶p̶e̶n̶ ̶p̶r̶o̶t̶o̶c̶o̶l̶ ̶t̶o̶ ̶b̶u̶i̶l̶d̶ ̶o̶n̶.̶

We really need an open protocol to win here.

> We really need an open protocol to build on.

I’d bet making a slack-compatible client or bridge isn’t hard, we all just instinctively know whoever develops it is going to get sued or taken down.

It feels like we quietly gave up on adversarial interoperability awhile ago, and act like we need a whole separate “open walled garden” when what we actually need are legal protections that prevent companies from suing/banning people who call their APIs. Slack, Facebook, etc, all only exist because they can ban/sue people who compete with their client experience.

I figure that will probably never happen in the US (maybe if someone rich starts it), but eventually someone outside of it will make such an adversarial integration and host it from some region that doesn’t care about US laws. Then, when they get away with it, we’ll all praise them as a genius and wonder how Slack could exist at all. The US has many international agreements keeping this illusion alive, but my guess is that even formerly stable markets like Europe could spawn such work if they decide to stop caring about ~1990s-2010s era contempt-of-business-model US laws.

But the point here is that you don't want the network effects. You want a chat server for people you know and explicitly invite, for a specific purpose, under your control. Maybe you want the data to never leave your colocated box and your VPN, and your server to have no public presence at all.

There are things that Slack cannot easily offer.

Like XMPP?

Or, perhaps the asynch chat thing is a distraction and we need something asynchronous that's well proven. Like... email?

Slack should never have been a thing IMHO. I remember first using it at a startup I was CTO of at the behest of the CEO ("everyone is using it"), back in around 2013. Instantly hated it. Just wish we could go back to good old email, TBH.

Matrix seems like a decent enough open protocol for a Slack replacement, with XMPP/IRC/IRCv3 being more useful for bare-bones chat transport.

This Chatto thing unfortunately uses a Protobuf custom API and is explicitly anti-compatibility with other systems. The lack of interoperability may end up killing it, unless the experience is much better than everything else.

So encrypted at rest but no E2EE, did I read that right?

Looks really nice, thank you for open-sourcing. I keep a directory of opensource alternatives. Would you say this is a Discord or Slack alternative?

> And it’s really good hosting! Chatto Cloud is launching with fully European and European-owned infrastructure, with more regions slated for launch in early 2027

With chat control that may not be so great…

Saw so many open source chats happen behind (or "in") Discord. Will this allow community members to drop in and chat and Google the contents?

It's a first-class PWA currently but no native desktop apps.

Seems like it, but since you can self host it, you still get a lot more control over the data than using one of the aforementioned hosted offerings

I've been testing/using chatto since early on and I'd say it's both and neither. It feels much nicer to use than Slack, but as of now it's missing some of the more "Enterprise" features. I would probably say it's a Slack-like Discord? But from the architecture it would be capable of playing as a full Slack replacement.

I also maintain a Chatto bot framework and a Tauri client, need to update those now :)

> You’re probably familiar with the one that rhymes with “knack”, or the one that rhymes with “beams”, or the one that rhymes with “this gourd”.

> Chatto is just like those.

from TFA. Seems yes.

Would English speakers pronounce this as "Chat-to"? To a Japanese person, this clearly sounds like "Cha-tto," which simply means "chat."

Linguist here. It would likely be pronounced with a flap/tap, i.e., it would rhyme with shadow

as an english speaker, i would pronounce it "chat-oh", but i'm open to correction

I don't know what the "official" pronunciation is, but I would say "Chat-o" is probably right.

At least here in colloquial "rolo" spanish people use to call "chato" (which would sound the same as "chatto") someone with a pug, snub nose

This is awesome! Some feedback - I can't tell anywhere from the website if there is mobile support (which is a must-have if I want to consider moving my company or friends over to this)

What's the rationale for the dual licensing? It looks like the Go backend is AGPL but the TypeScript frontend is Apache 2.0.

Why not keep it all AGPL?

Backend under AGPL prevents someone hosting it as a service. AGPL specifies that hosting _is_ distribution. Therefore, anyone hosting it must do so with public code. This provides a soft form of exclusivity to run their own Cloud.

A frontend, permitting customizability, white-labeling, and so on, makes more sense to be more permissive.

Grafana is a solid example to illustrate why.

Moved from Apache to AGPLv3 in 2021 specifically so cloud providers couldn't host modified versions without contributing back, while keeping plugins Apache-licensed.

AGPL stops others from running a competing cloud service using the Go backend. It does nothing for the frontend except scare off enterprise users.

Very cool. I don't usually get excited for new chat apps, but I like the idea of having one frontend for multiple servers instead of pushing hard on p2p or federation.

I do also still like irc, but haven't used it much in recent years because most of the people I talk to are using discord now.

One front-end for multiple servers is how you end up reimplementing XMPP (bar federation) before you know it: servers are not guaranteed to run identical/compatible versions -> you bake versioning at capability level in the protocol -> you make clients and servers degrade predictably when that happens -> you write a standard to document it formally -> you invite around the table those authors of alternative client and server implementers and boom, you've got the X in XMPP, and the XEP standardisation process and the XSF to support it.

Couldn't help but smile because "chato" in portuguese means "boring", and this seems very easy to set up and use.

Here's to more boring software! :)

Can also mean annoying. As a general recommnedation, before naming a project or company something, always search whether it means something bad in the top 10 most spoken languages.

For portuguese/spanish, there is always a high chance of being a slang that is NSFW

chudo missed opportunity

Alright, I was vaguely interested for a little, but you convinced me to avoid it.

Can it be installed on Cloudflare or Vercel or something else that is easy/cheap/free?

> We really need an open protocol to build on.

I’d bet making a slack-compatible client or bridge isn’t hard, we all just instinctively know whoever develops it is going to get sued or taken down.

There are things that Slack cannot easily offer.

Like XMPP?

Or, perhaps the asynch chat thing is a distraction and we need something asynchronous that's well proven. Like... email?

Matrix seems like a decent enough open protocol for a Slack replacement, with XMPP/IRC/IRCv3 being more useful for bare-bones chat transport.

I run something similar with livekit, all on hetzner. its exceedingly affordable for a bunch of people at once to use it.

Very cool! You should request being added to https://european-alternatives.eu/

Seems like it, but since you can self host it, you still get a lot more control over the data than using one of the aforementioned hosted offerings

Amazing. And with SSO out of the box without weird "Oh, SSO is Enterprise only" BS.

It's a first-class PWA currently but no native desktop apps.

Does this federate with anything, like Matrix or XMPP? If it is locked into a single software, I fear nobody will ever switch to it (I have too many chat apps already!)

Needs drop in voice rooms a la Discord or Slack's Huddle

> You’re probably familiar with the one that rhymes with “knack”, or the one that rhymes with “beams”, or the one that rhymes with “this gourd”.

> Chatto is just like those.

from TFA. Seems yes.

Linguist here. It would likely be pronounced with a flap/tap, i.e., it would rhyme with shadow

as an english speaker, i would pronounce it "chat-oh", but i'm open to correction

I don't know what the "official" pronunciation is, but I would say "Chat-o" is probably right.

At least here in colloquial "rolo" spanish people use to call "chato" (which would sound the same as "chatto") someone with a pug, snub nose

A frontend, permitting customizability, white-labeling, and so on, makes more sense to be more permissive.

Grafana is a solid example to illustrate why.

Moved from Apache to AGPLv3 in 2021 specifically so cloud providers couldn't host modified versions without contributing back, while keeping plugins Apache-licensed.

(They do have end-to-end encryption for video.)

I hope they introduce some sort of public read-only view that an admin can enable. Discord has https://www.answeroverflow.com/ and https://www.linen.dev/

I created a Tauri based app but IMO it's not ready for prime time on mobile. On desktop, it's my daily driver for Chatto. If anybody wants to contribute, the foundation (desktop & mobile) is at https://github.com/teal-bauer/chatto-tauri

Yeah its unfortunate there's an AI app on the apple store with the same name

> And you can just self-host it. For free, too! (A weird thing to write, but the OSS chat app space has become very weird in many ways!)

Wait, what? There are open-source chat apps that you have to pay to host yourself? How does that work? Or did I misunderstand?

Many otherwise open-source chat apps are "open-core," they tie certain features to a subscription. Can be things like chat history, voice calls, video calls, but a very popular one is SSO and AD/LDAP integration.

Yeah a lot of them like Mattermost become surprisingly limited unless you pay. It's very annoying.

Congrats for open sourcing it, looks interesting!

How does this compare to fluxer.gg though?

The part that I really liked about chatto is that it seems to be made very easily to self host which is something that I really appreciate actually.

I have been patiently waiting for fluxer, but honestly I just want to self host and have it available and fluxer has been sitting on that for a while

soooooo campfire then

There's space for more than one self-hosted chat app in the world. Also very ignorant comment towards a project someone probably spend a lot of time on.

Off the bat, it seems that campfire doesn't support voice/video calls. So no, not at all

I also maintain a Chatto bot framework and a Tauri client, need to update those now :)

What makes it nicer to use than Slack?

> Chatto aims to be the group chat application that you actually enjoy using.

So not like Discord or Slack?

> This is what it looks like:

Discord and Slack?

I mean, OK, it has EU hosting and that is good. But I see nothing obvious here that solves the noise and irritation of Discord and Slack.

most complains i see about the others are performance-related, not looks-related. and chatto is trying to be performant.

AGPL stops others from running a competing cloud service using the Go backend. It does nothing for the frontend except scare off enterprise users.

You can totally run AGPL code as a service. You can run it as a service unmodified or if you modify it, you just need to make the source available.

Hot damn. This is the big one.

I’m happy to announce that Chatto, the group and team chat application that I’ve been working on for the past year or so, is now officially Open Source, and available for anyone to self-host.

The fastest way to give it a try is through Homebrew:

brew install chattocorp/tap/chatto
chatto init
chatto run

See Chatto’s Getting Started Guide for details. Or stick around to hear more!

Chat Just Got Real

Chatto aims to be the group chat application that you actually enjoy using. You’re probably familiar with the one that rhymes with “knack”, or the one that rhymes with “beams”, or the one that rhymes with “this gourd”.

Chatto is just like those. Except you’re going to love how compact and snappy it is. And that it’s Open Source. And you can just self-host it. For free, too! (A weird thing to write, but the OSS chat app space has become very weird in many ways!)

This is what it looks like:

A screenshot of Chatto

If you want to see it in action, drop by the Chatto HQ Community!

It’s designed to be extremely easy to self-host on your own infrastructure. In its most basic shape, you just run the executable, and that’s it. It even serves its own frontend!

It’s very light on resources, and probably has the snappiest frontend that you’ve ever used in an app like this. It puts data protection and privacy first, with all personal and chat data fully encrypted at rest with per-user keys that get shredded when a user decides to delete their account.

Each Chatto server powers a single community, with no federation of data between servers, nor any third-party tracking or analytics. If you want to hang out in multiple servers at once, the client will simply connect to all of them directly. If you want to host multiple communities, just spin up multiple Chatto processes. Easy!

Chatto comes with full support for voice and video calls, with screen-sharing, built in. Calls are fully end-to-end encrypted and will scale to as many participants as your infrastructure can handle.

And you can use it today, for free, by self-hosting it on your own server. Binaries are available for Linux (x86_64 and ARM64), macOS, and Windows; head over to the Chatto Self-Hosting Documentation site to get started.

Chatto Cloud

If you prefer someone else to take care of the hosting, I’m also happy to announce that Chatto Cloud will soon enter public beta. Chatto Cloud’s offering is very simple: it provides paid hosting for Chatto servers — and that’s it. No premium subscriptions, no ads, no icky bits. Just hosting.

And it’s really good hosting! Chatto Cloud is launching with fully European and European-owned infrastructure, with more regions slated for launch in early 2027. Every Chatto server on Chatto Cloud benefits from automatic scaling, nightly backups of all data, and zero-downtime version upgrades.

There’s no lock-in; servers hosted through Chatto Cloud are 100% compatible with self-hosted ones, and you can pack up your data and move into or out of Chatto Cloud at any time.

If you want to get notified about the start of the beta, please see the end of this post for a low-volume newsletter you can subscribe to.

What’s Next for Chatto

Chatto is now at version 0.4. I consider it stable enough for production use, but there are a few important features still missing — head over to the Chatto Roadmap if you want an overview.

The focus for Chatto 0.5 will be on additional safety features (content reporting and moderation) as well as polishing the client, particularly its multi-server functionality. I have some fun stuff planned for this that I can’t wait to put into people’s hands.

I expect Chatto to hit 1.0.0 in about 6-12 months. Until then, there may still be breaking changes, even though I’ll be trying to keep them to a minimum. If you do decide to self-host, please be ready to update to new versions as they are released.

Get in Touch

It’s been an exciting journey so far and I’m looking forward to finding out what’s ahead. If you’re self-hosting Chatto, I’m super eager to hear from you about your experience — please don’t hesitate to head over to the Chatto HQ community and get in touch.

Also please feel free to drop by and say hello if you’re interested in Chatto for your company, Open Source project, or similar. I’d love to learn more about your requirements, and help you get set up.

Links

Chatto HQ Community - we have a #self-hosting support channel!
Chatto Self-Hosting Documentation
GitHub Repository
Chatto on Bluesky

If you want to be notified about new releases or the start of Chatto Cloud’s beta, you’re invited to subscribe to the Chatto announcements newsletter. It’s super low-volume (~1 email per month), and is only used for notifying you when exciting new stuff becomes available.

I run something similar with livekit, all on hetzner. its exceedingly affordable for a bunch of people at once to use it.

I hope they introduce some sort of public read-only view that an admin can enable. Discord has https://www.answeroverflow.com/ and https://www.linen.dev/

Yeah its unfortunate there's an AI app on the apple store with the same name

There's space for more than one self-hosted chat app in the world. Also very ignorant comment towards a project someone probably spend a lot of time on.

What makes it nicer to use than Slack?

You can totally run AGPL code as a service. You can run it as a service unmodified or if you modify it, you just need to make the source available.

Off the bat, it seems that campfire doesn't support voice/video calls. So no, not at all

Interesting but could you put few screenshots there? Of both desktop and mobile? It is really hard to invest time into installing something that you cant see anywhere prior, and it will be really easy to do for someone that is using it daily. Sorry for complaining. Seems like nice project.

Yeah a lot of them like Mattermost become surprisingly limited unless you pay. It's very annoying.

Mattermost's licensing is a little confusing, but from what I understand, you're only really super-restricted if you use the prebuilt binaries (which have a different license than the source code).

IIRC if you build it yourself it's pretty much all AGPL, with few limitations.

I have been patiently waiting for fluxer, but honestly I just want to self host and have it available and fluxer has been sitting on that for a while

most complains i see about the others are performance-related, not looks-related. and chatto is trying to be performant.

I'm the developer behind Fluxer – self-hosting is ready to use already [1][2][3], people are using it actively currently, and I'm currently working to make account switching across instances in the desktop app a reality. This, with a big voice update around the corner, will let us move much faster moving forward!

[1]: https://fluxer.app/blog/mobile-clients-and-fluxer-v2

[2]: https://docs.fluxer.app/operator/get-started/

[3]: https://github.com/fluxerapp/fluxer

It is not looks or performance (I have no idea) I am talking about. It is the shape of the functionality — the intent of it.

All these systems end up with far too much furniture on screen, and this appears no exception.

I will test it, of course. But the promotional material argues against itself.