Calls, without leaving the room
Tap the video icon in any conversation for encrypted voice or video — no separate app, no phone number.
Built on MatrixRTC.
Long day? Find the important ones. Close it.
Crux is a messaging app built on Matrix — an open network for chat, the way email is an open network for mail. It sorts every conversation before you even open the app: the ones that actually need you rise to the Peak; everything else settles quietly on the Slope. No wall of chats to dig through after a long day.
Open source · in beta testing Scan to try Crux Apple's beta testing app — or tap here → See how it ranks Once you're in and you've made an account on a server: open Search and
type #cruxroom:joshuarocks.me to say hi in the sample room.
The problem
You shouldn't have to go looking.
Technology is supposed to save you time. Somehow, every messenger you own still works the exact same way — and that way slows you down. Each one applies a single sort key: recency. It's the easiest sort to write — and the worst one to live in after a long day. The message that actually mattered doesn't stay at the top. Newer, more trivial things just pile on top of it, and you're the one who has to scroll to find it.
That costs you time.
Every conversation, treated as equally urgent — until you look.
The Mountain Want to take a look?
Want to take a look?
Here is the app.
The Mountain sorts your messages — or see all of them, unsorted, in Rooms and Spaces. Swipe a card to mark it read and it clears off the Mountain; nothing's ever hidden, every conversation still lives on in Rooms.
- 1 Open the app — cards are already sorted into Peak and Slope
- 2 Swipe a card to mark it read; it clears off the Mountain entirely
- 3 Still want it? Every conversation lives on in Rooms either way
The Mountain: Peak above, Slope below.
The ranking
What reaches the top isn't time.
Crux scores every conversation from a handful of honest signals — plus, if you want it, a small on-device AI model that reads how urgent your unread messages sound. Nothing about your messages ever leaves your phone to do this.
Mountain needs you · 5
MC
Maya Chen just need to know by 4
DM★urgent
13PD
#incident-bridge @you acked? api-gateway p95 climbing
@yougroupurgent
8PN
#release-crew @you tagging you on the changelog
@you★group
8D
Dad call me when you get a sec
DM
7S
Climbing Fri? booked the wall for 7
DM
7Slope still there, not shouting · 3
SB
#standup 12 updates posted
groupmuted
-21SB
Deals & Promos 🔥 48h flash sale ends soon
groupmuted
-22DG
eng-weekly This week in the codebase
groupmuted
-22Also inside
One more thing…
Or maybe a few more?
The Mountain is the headline — it isn't the whole app. Crux still does everything you'd expect from a chat app, and then some.
Share where you are, live
Send a one-time pin or share your location live for a while — it updates on its own and stops when you're done.
Position updates are just encrypted messages — nothing leaves Matrix.
React without a reply
A quick 👍 or ❤️ on any message — the small stuff that keeps a conversation moving.
Find anything, fast
Rooms, people, spaces — one search bar covers all of it.
Tune what counts
Turn any signal up or down — mentions, favorites, direct messages, group chats, muted rooms — and watch your own Mountain re-sort.
Settings → Tune Ranking.
The network Crux isn't a network.
Crux isn't a network.
It's a client for one that already exists.
Underneath, Crux speaks Matrix — an open, federated protocol. A server is just an address, like an email domain. So you can sign up anywhere, and the person you're talking to doesn't need Crux at all: any Matrix app works, on any server. Some servers even bridge outside networks in. And all of it is end-to-end encrypted.
Getting an account costs nothing: sign up right inside Crux on matrix.org to start, no separate site required. Prefer somewhere else? Any Matrix server works — your school, your company, a community you're already part of — or you can run your own.
Native Matrix app — encrypted Bridged network
Bridges are community-run and server-dependent — not every server offers one.
Try it with someone
Come chat in the sample room.
We keep a room open just for people trying Crux out. It's still a real room on a real server, so you'll need an account first — that takes a few taps.
- 1 Make an account (matrix.org works right in the app)
- 2 Open Crux, tap Search
- 3 Type exactly
#cruxroom:joshuarocks.me - 4 Tap the room, then Join
A room is just Matrix's word for a conversation — a group chat like any other, except it isn't tied to one app. Anyone on any Matrix app can join with that address, the same way anyone can email an address without needing your exact mail app.
planned
Full-text search
Search the words inside your messages, not just room and people names.
planned
Filter bridged chats
Keep the noise out of the Mountain.
planned
Share Sheets
Send into Crux from anywhere in iOS.
planned
Threads
Follow one branch of a busy room without losing the rest.
planned
Screen sharing
Show your screen on a call, not just your face.
planned
Typing indicators
See when someone's actually writing back.
planned
Presence
Know who else is online before you send something time-sensitive.
planned
Siri & App Intents
Ask Siri to check the Mountain or send a reply — including the smarter, on-device Siri coming in iOS 27.
planned
On-device translation
Read any message in your own language, translated right on your phone.
Reach the bottom of your Mountain.
Crux is open source and in beta testing now on TestFlight — Apple's beta testing platform — fully native, built in SwiftUI. Point your camera at the code, or tap through on your phone.
Scan for TestFlight