Private messaging · Your server + apps

Talk with your people.
On your own server.

Family photos, work documents, messages and calls in a system you control. KOYA combines a server on your equipment with apps on Android phones.

Try the demo Explore the security Find your option

Android 7.0 or later · Join by personal invitation

End-to-end encryption protects conversation content. The server delivers messages without the keys to read them.

9:41▮▮▮ ▰

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Our little circle3 members

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TODAY

A quiet weekend out of town?10:24

Yes! No rush, just coffee ☕10:25 ✓✓

Weekend plans.pdfPDF · 240 KB

I’ll send the route here. See you soon!10:26 ✓✓

Message…

Just your peopleJoin by invitation

End-to-end encryptedProtected on your device

ILLUSTRATIVE CONVERSATION · FICTIONAL CONTENT

A server you control

Participants by invitation

Encrypted conversations

小屋 · KOYA

A small home. A meaningful idea.

A place for
your people.

In Japanese, 小屋 means a hut or small cabin. That is our idea of KOYA: a quiet place to gather with family or a team, talk about what matters and hear each other.

You choose the people. Encryption protects the conversation.

Explore the security ↗

A communication system you control

Your server.
Your rules.

License the KOYA server and apps, host the system on your equipment and invite the people you want to talk with.

Your server

Host KOYA on your own infrastructure. You decide where your communication system runs.

Your people

Invite participants, approve devices and revoke access when it is no longer needed.

Your retention rules

Control device history retention and attachment availability. Downloaded copies remain with recipients.

Protected content

Messages and files are encrypted on participant devices. The server delivers them without decryption keys.

Find your option ↗

On-Premise · Server + apps

Your conversations.
On your equipment.

KOYA is licensed software: the server runs on your equipment and apps on participant phones. You choose hosting, users and maintenance.

Your participants’ devices
Your server
Your access and maintenance rules

Infrastructure you control

Run KOYA on your home computer or company server. All system components run on your infrastructure. If you rent a server, choose a provider you trust.

Access under your control

You manage the server and decide who gets access. Keys are generated on your equipment during setup. Remote support connects only with your permission.

Local licence verification

Windows Home verifies a licence bound to your server key locally. Activation does not transmit conversations or personal files. Transfer terms are agreed when purchasing.

Maintenance on your terms

Your administrator controls devices, backups and updates. Business support scope, response times and responsibilities are specified in the contract.

The public demo room lets you explore KOYA. Use your own server and private invitations for personal conversations and business data.

What your purchase covers

Usage rights for the KOYA server and apps. Scope, price, updates and support are agreed before purchase. Organisational deployment requirements and SLAs are discussed separately. Payment and delivery are contractual; this website is not a contractual offer.

Where does my data stay?

A self-hosted installation sends messages and files through your server; conversation history stays on participant devices. Opening a shared location in Google Maps contacts Google. Your chosen certificate authority issues the connection certificate.

What does On-Premise mean legally?

You receive software usage rights and operate the system yourself. Applicable duties depend on actual operation and the contract. On-Premise alone does not grant an exemption from legislation. Personal-data roles, Russian messaging-service obligations and cryptographic licensing requirements need a separate assessment for each delivery.

Can a regulated organisation use KOYA?

Information-security and documentation requirements are discussed before deployment. KOYA is not offered as a certified security product; systems with special requirements need a delivery-specific assessment.

Messages, files and calls

Everyday communication.
One app.

Talk to family, send a document to a colleague or share a meeting location. No phone number is required to register.

Choose how to talk

Private chats, groups, voice messages, voice and video calls. Type a reply, record a message or call, all in one app.

CHATS · VOICE NOTES · CALLS

Share what matters

Send photos, videos and documents with captions. Transfers resume after a dropped connection. Share a location so the recipient can open it in Google Maps.

PHOTOS · VIDEOS · FILES

Make it yours

Choose a theme, notification sound and history retention period. Mute notifications when you need to focus.

THEMES · PATTERNS · PREFERENCES

Privacy built into the system

The server delivers.
Only you can read.

Messages and files are encrypted before sending. Reading keys stay on participant devices; the server receives encrypted data.

Your phone

Message relay

Their phone

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9b52 f18e 7c04 d6a1

The principle in transit: message content is hidden from the relay.

An explanation of the principle, not an actual network packet.

Keys stay with the participants

Each private conversation has its own keys. They change as messages are exchanged and stay on participant devices.

Protection against tampering

The app verifies protected data to detect changes made during transmission.

Your history stays with you

Conversations live in an encrypted database on your phone. A PIN or supported biometrics protects access to the app.

Temporary delivery, private content

The server holds encrypted packets until the recipient acknowledges them, for up to 24 hours. It then deletes them. Decryption keys stay with the participants.

Deliver conversations. Keep their contents private.

The server never receives your conversation keys. It forwards encrypted messages and files and helps connect calls. Delivery still needs technical information: IP addresses, participant names and identifiers, room, timing and routing. End-to-end encryption hides the content, not this metadata.

Your name.
Your choice.

Starting a conversation should not mean handing over a phone number, email address or identity documents. Choose a name your people will recognise — your own, or one you make up. KOYA does not tie your conversations to those personal details. Your circle grows through personal invitations, with end-to-end encryption protecting what you share.

How KOYA handles your data ↗

At home and at work

Family conversations.
Working together.
Your people.

AN EXAMPLE CONVERSATION

The project team

The updated launch plan is attached.

Let’s work through the details here.

Illustrative conversations with fictional data.

Choose your use case

From a family PC
to company infrastructure.

For home, a server on the family PC. For business, a deployment and delivery terms tailored to the organisation.

For family and friends

KOYA Home

Windows demo available

Your place for photos, plans and conversations. A server on the family PC, KOYA on phones, and access through your invitations.

Setup wizard for Windows x64
Public static IP connection without a required domain
Updates and backup restoration

Download Home for Windows ↗

For teams and organisations

KOYA Business

For organisational deployment

Work messages, documents and one-to-one calls on your infrastructure. You manage device access and retention settings.

Server hosted on your infrastructure
Invitations, device approval and access revocation
Licence and support terms agreed by contract

Explore team capabilities ↗

For larger organisations

KOYA Enterprise

Discuss requirements

For organisations with specific workload, integration and continuity requirements. Discuss the task and define solution scope before signing a contract.

Architecture scoped to your workload
Integration and resilience requirements
Acceptance testing and support terms

Discuss deployment ↗

Try KOYA free in the demo. Ongoing use of the server and apps requires a licensed delivery; scope and price are agreed before purchase.

Windows x64 · 0.6.1-preview

Your family’s own messenger

KOYA Home runs on your Windows PC while the family talks on Android phones. The wizard helps with setup. Internet access requires a public static IP address, available from your ISP.

Unpack the full package

Download the complete ZIP and run KOYA-Home-Setup.exe. The wizard sets up the server on your PC; install KOYA on Android phones for messaging and calls.

Prepare your network

The wizard explains the computer and router settings needed to connect phones over the internet. The server can start automatically with Windows.

Invite your people

Activate the owner on your primary phone, then issue single-use QR invitations. The owner can enable cascading invitations. The website’s public demo room is separate from your server.

A demonstration package for evaluating KOYA, not for production use. No licence is required for testing. Each file is limited to 1.5 MiB. The installer is not digitally signed for Windows. Contact us about commercial delivery and support.

Download Windows Home · ZIP SHA256 ↗Wizard guide Hardware

KOYA Home · Windows

Your home server, one clear step at a time

Extract the entire ZIP before opening the wizard. These are real screens with example values. The address 203.0.113.10 is for documentation only; enter the public static IPv4 assigned by your ISP. Screens are currently in Russian.

Home demo limits

Each file: Up to 1.5 MB
File storage: Files travel inside messages and are stored on phones; no separate cloud drive.
Recipient offline: The server waits up to 24 hours for delivery and removes packets earlier once delivery is acknowledged.
Participants and calls: For evaluation on a few phones. There is no fixed participant limit; concurrent call capacity depends on the network and load and is not guaranteed.
Trial duration: No expiry timer. Keep the PC awake and online.

The demo does not include a commercial licence. Production terms and supported capacity are agreed when purchasing.

More about sizes and delivery

Sizes use binary megabytes (MiB). Pending encrypted delivery is limited to 512 packets per recipient and 64 MiB in total. A packet is a transmission unit, not necessarily one chat message. Delivered chat history follows the app’s retention settings.

Demo features and limits

Home is a Windows server; the APK is the Android app. Evaluate messaging, voice messages, private voice and video calls, invitations and access management. Phones need network access to your server.

Home limits each file to 1.5 MiB. There is no enforced trial expiry and this package needs no licence file. Concurrent call capacity is not guaranteed: it depends on your PC, network and connection route. This package is for evaluation, not mass or production use. The Windows installer is not digitally signed. Commercial licensing, support and deployment scope are agreed when purchasing.

Home creates your own private room. The website QR leads to a separate public demo room.

1. Server address and protection
Extract the entire ZIP and open KOYA-Home-Setup.exe. If the wizard requests permission to run, approve only a package obtained from the KOYA website. Ask your ISP for a public static IPv4. Keep the default local certificate: your QR carries trust, with no external certificate service or email.

2. Ports and router setup
Open the step-by-step guide in the wizard. It shows the PC’s local IP, router address and rules for your selected ports. Reserve the PC’s address, configure port forwarding and allow the listed inbound ports in Windows. The default local certificate shares trust through your QR; no email or external TCP 80 is required. Confirm setup before preparing the server.

3. Licence or demo
The demo needs no licence file. For a purchased package, send only the activation request and order number to the publisher; install the returned license.json. Keep private keys on your equipment.

4. Connect participants
Start the service, connect the owner phone with private QR codes and invite participants from the app. Test a second phone over mobile data. Keep the server PC awake and online.

What should I configure in my router?

Open the wizard’s network guide and your router settings. Sign in using your router password.
Reserve the PC’s local address under LAN / DHCP. Step 1 needs the server’s public static IPv4. Behind a router, use the connection’s public address and forward to the PC’s local address.
Create the forwarding rules listed by the wizard. Local certificates do not require external port 80. Only the optional Let’s Encrypt mode requires its certificate forwarding rule.
Add Windows inbound TCP and UDP rules for the listed ports. Keep internal messaging and directory ports private.
Save the rules, confirm network setup and prepare the server. Test a phone over mobile data with Wi-Fi off.

Ask your ISP about CGNAT or blocked inbound ports. Two routers require forwarding on both. Use the main Wi-Fi or a LAN cable. Find the router address under Default Gateway in ipconfig; use the device’s administrator credentials. Rostelecom QBR-1041WU v2S uses Security → Port forwarding; other models differ. If mobile data works but the same invitation fails on home Wi-Fi, check NAT loopback support. Keep existing rules and ISP settings; do not bypass HTTPS verification.

Home / Business / Enterprise

Hardware to plan for

A family needs stable internet and an always-on PC. Organisations size hardware by users, files and concurrent calls. These are planning estimates; the configuration is scoped to your workload.

Home · home PC

Supported Windows 11 x64. 2 CPU cores, 4 GB system RAM minimum; 8 GB recommended. SSD with 2 GB free plus data and backups. TPM 2.0 preferred.

Public static IPv4 and port forwarding to the PC. The default mode needs no external certificate authority or port 80. For a small circle, plan stable 20 Mbps in both directions, Ethernet and an always-awake PC.

Business · VPS

Small-pilot starting point: Linux x64, Docker Compose, 2 vCPU, 2 GB RAM and 20 GB SSD plus data and backups.

Public IPv4, permitted TCP/UDP and a 100 Mbps starting bandwidth budget. Check traffic, packet-rate and UDP limits with your provider. This is not a guaranteed call count.

Enterprise · your infrastructure

Separate signalling and TURN nodes. A planning example: 2 signalling nodes at 4 vCPU / 8 GB RAM and 4 TURN nodes at 8 vCPU / 16 GB RAM with 10GbE.

Sizing considers redundancy, network traffic and node failure. Solution scope and capacity are determined for your deployment; these numbers are planning estimates.

1,000 simultaneous one-to-one video calls: a sizing example

At 2 Mbps sent by each participant, with every call relayed by TURN, aggregate relay ingress is about 4 Gbps and egress about 4 Gbps. A planning margin of 25% gives about 5 Gbps in each direction. Lower TURN usage requires a different connection policy. The current TURN-enabled profile uses relay mode, so budget for 100% TURN. The 2 Mbps value is an Enterprise planning assumption, not the current demo bitrate. Signalling and other traffic are additional. This is a calculation, not a KOYA benchmark.

The server needs no camera or dedicated video GPU: phones process video. Calls need bandwidth and a stable network; files and backups need disk space. The Home demo allows attachments up to 1.5 MiB.

Certificate requirements and Windows support: Let's Encrypt ↗ · Microsoft ↗

PURCHASE & LICENSING

Find the right KOYA setup

Email or call us with your users and preferred server location. We will discuss a family or organisation package, licence price, setup and support. All terms are agreed before purchase.

Dmitry Nikolaevich Boyko · Russian professional income tax payer (self-employed)
Taxpayer identification number (INN): 190158352451

dmitry.boyko@gmail.com +7 903 907 6399

This website does not take payments. Do not send passwords, private keys, private invitations or participant conversations.

Buying, activating and transferring your licence ↗

One space. Many reasons to connect.

For business.
For everyday life.
For trust.

Bring your family, project team or partners into their own space. You decide who connects.

Leadership and business owners

Development plans, preparation for negotiations, budgets and decisions before they are announced.

A closed circle of participants; discussion content stays unreadable to the server.

Teams and internal projects

Department conversations, launch coordination, working drafts and internal documents.

Separate conversations and groups for work; attachments are encrypted before sending.

Consultants, studios and contractors

Discuss proposals, designs and project terms with a client in a separately invited circle.

Documents are shared with conversation participants; decryption keys are not given to the server.

Families and close friends

Photos, household plans, trips and conversations that do not need a public audience.

No phone number or email registration; choose your own name.

Creative projects and communities

Unpublished ideas, works in progress and plans for a small private community.

Personal invitations help build your circle; conversations live on participant devices.

Trips and temporary teams

Organise an event, expedition or shared journey with a dedicated chat for the task.

Choose how long your own history stays; other participants control their copies.

KOYA for your company

Your conversations.
Your infrastructure.

Work discussions, documents and calls on your organisation’s server. You manage employee access and system maintenance. Registration needs no personal phone numbers; conversation keys stay on participant devices.

The employee app runs on Android. Server deployment, user counts and support terms are scoped to your organisation.

Start with two Android phones: exchange messages, send a file and call each other. Use test data: the demo room is public.

Explore the demo

Match the protection to the task

Personal and internal

Everyday family conversations, work coordination, ideas and small-team documents are KOYA’s core use cases.

Confidential

Trade secrets and client materials call for agreed access policies, trusted devices and an assessment of your organisation’s requirements. End-to-end encryption protects content in transit; it cannot stop a recipient from saving or forwarding it.

Special requirements

Three simple steps

From installation
to your first conversation.

Install KOYA

Download the signed Android APK. If prompted, allow installation from your chosen source.

Protect your space

Set a PIN and choose a display name. Supported devices also offer biometric unlock.

Accept an invitation

Get a link or QR code from your room administrator. Scan it with the camera or import a QR image.

Before the first hello

Before you
connect.

What personal details do I need to join?

No phone number, email address or identity documents. Choose a display name — a pseudonym is welcome — and join through a personal invitation. The app creates keys on your device for secure communication.

How many people can join a group?

Up to 32 participants in one group chat. Separate groups can serve different purposes. User and concurrent-call capacity is sized for your installation.

What is available for Windows?

An Android demo app and a separate Windows Home server with a setup wizard. The ZIP includes setup, activation, update and recovery instructions. Use the Android app for messaging and calls.

What can I try in the demo?

Use two Android phones to try chats, voice messages, files, voice and video calls. Download the separate Windows Home demo to explore hosting your own server. Demos are not for production use.

Does my server need a separate APK?

The same APK can connect to different servers through invitations. Your family or organisation needs its own server and private invitations. The public demo room on this site is for testing only.

Can the server read a conversation or open a file?

The server delivers encrypted messages and files without reading keys. Content opens on participant devices. Connection information such as IP addresses is needed to operate the service and is visible to the server.

Can I join without an invitation?

A private room needs a valid invitation from its administrator. Share private links and QR codes only with trusted people. This website also offers a public demo invitation for testing; do not use that room for private conversations.

What if the other person is offline?

The server temporarily holds the encrypted message and delivers it when the recipient connects, even if the sender has left. It deletes the packet after acknowledgement or after 24 hours. If the queue is full or the sender has no connection, the message stays on their phone for retry. Both participants need an updated app and must have exchanged keys online at least once. Background operation depends on Android settings.

Where do messages and files live?

Conversations live in an encrypted database on your phone. Attachments are encrypted before upload and stored on the server for delivery. The sender chooses availability within server policy. Removing a server file does not remove copies already downloaded by participants.

Does deleting history delete everyone’s copy?

No. Local clearing and retention settings apply to your device. They do not remove copies saved or exported by another participant.

Can I restore history after reinstalling?

Save an encrypted backup using KOYA and keep its password. You can restore history from that backup after reinstalling. There is no automatic cloud restoration; an invitation restores room access but does not replace a conversation backup.

Is there an iPhone version?

This website currently provides a tested Android build. A released iPhone version is not offered here.

Will messages and calls arrive after I close the app?

Enable Background connection and permissions in the KOYA menu and allow notifications and background operation. One service waits for both messages and calls, with one quiet ongoing KOYA notification. Delivery uses your own server without external push services. Message alerts do not reveal text; chats require your PIN. After Android Force stop, open KOYA again. Device battery restrictions can affect reception.

DEMO

Testing · Demo mode

Try KOYA
on two phones.

A shared room to explore messages, voice notes and one-to-one audio and video calls. Install the APK and join from both phones with this invitation.

This room is public: any website visitor can join. Use test messages and files. The demo APK lets you explore the main features; the download includes no commercial licence. There is no trial expiry timer, but public demo availability may change. Use the Home package for your own private circle.

Public demo limits

Each file: Up to 20 MB
File storage: 512 MB shared by everyone in the room, not per phone.
Recipient offline: The server waits up to 24 hours for delivery and removes packets earlier once delivery is acknowledged.
Participants and calls: For evaluation on a few phones. There is no fixed participant limit; concurrent call capacity depends on the network and load and is not guaranteed.
Trial duration: No expiry timer. Public demo availability may change.