SimpleX Chat

1. Project Overview

1.1 basic information

1.2 Project Positioning

SimpleX Chat is a decentralized encrypted communication platform with privacy as the core design principle. Its positioning can be summarized as follows:

-Technical level: It is the first "no user identifier" messaging network-instead of using mobile phone numbers, email addresses, user names, public key fingerprints, or any globally unique identifiers to identify users, they communicate through one-way (simplex) message queue addresses. Users and each contact use a separate message queue collection, similar to assigning each contact a unique "one-time address", but automatically managed and rotated by the client.

- product level : provides iOS, Android, desktop (Mac/Linux/Windows) and terminal CLI full platform clients, with functions covering text messages, voice messages, picture/video/file transfer, audio and video calls, burn after reading, group communication and chat robot SDK.

- Ecological level : It is not only a chat application, but also a general message and application platform -SimpleX Messaging Protocol (SMP) can carry IoT device communication, AI service interaction, security monitoring and robot control systems and other wider application scenarios.

Core Value Proposition: "You were born without an account-your conversation belongs to you, no one can peep, no one can take away. "** (Declaration from WHY page of official website)

1.3 development process

2. Core Competence

2.1 Userless Identifier Architecture (Core Differentiation)

The SimpleX does not use any globally unique user identifiers. Contrast with traditional communication software:

Mechanism: When a user establishes a connection with each contact, the system automatically generates a set of one-way message queues (SMP queues). These queue addresses are temporary, unique per connection, and can be rotated automatically by the client. The relay server only knows that "there is a queue in use", but does not know who it belongs to and who it is connected.

2.2 multi-layer end-to-end encryption

-Double Ratchet algorithm: The message layer uses dual-ratchet end-to-end encryption to provide forward security (Forward Secrecy) and intrusion resilience (Post-Compromise Security / Break-in Recovery).

-Additional encryption layer: On top of the Double Ratchet, you SimpleX add another layer of end-to-end encryption (message delivery encryption layer) to each encrypted message, so that the traffic sent and received by the server cannot be associated in the ciphertext.

-Post-quantum hybrid encryption: Continuous post-quantum hybrid key exchange has been implemented. It is one of the very few instant messaging tools that have been deployed to resist quantum encryption.

-Message padding: All messages are padded to a fixed size (16KB block) before each layer of encryption to prevent traffic analysis.

2.3 Decentralized Relay Network

-The server is stateless relay node: does not store user accounts, contact lists, and delivered messages.

-Servers are not connected to each other and do not know each other: There is no global network diagram and cannot be attacked as a whole.

-Users can build their own server or use a pre-configured server, and can switch servers at any time without losing contacts or messages.

-2-hop onion route: The sender forwards the message to the route selected by the receiver through the SMP route selected by itself to protect the sender IP address and session information.

-Each conversation uses 4 different servers, any one is breached does not affect the overall security.

2.4 anti-garbage and anti-harassment

-No one can contact you without a one-time invitation link or temporary user address.

-Temporary user addresses can be changed or deleted at any time without losing existing contacts.

-Fundamentally eliminate user ID-based spam messages and cyber violence.

2.5 Full Functional Matrix

2.6 end-to-end encryption security horizontal comparison

SimpleX official E2EE safety comparison table:

Among the above six security dimensions, SimpleX is the only communication tool that passes through all items.

3. Technical Architecture

Overall 3.1 Architecture

  用户的设备                      互联网                        第三方中继服务器
 ──────────────────    ──────────────────────    ─────────────────────────
                                                      ┌──────────────────┐
  ┌──────────────┐                                    │  SMP Router A    │
  │  Chat App    │                                    │  (发送方选择)     │
  ├──────────────┤                                    └────────┬─────────┘
  │ SimpleX      │                                                │
  │ Agent        │  ──────── TLS ────────               ┌────────┴─────────┐
  ├──────────────┤                                    │  SMP Router B    │
  │ SimpleX      │  ─── SimpleX Messaging Protocol ──▶ │  (接收方选择)     │
  │ Client       │                                    └──────────────────┘
  └──────────────┘

Hierarchical Architecture:

1. Chat App layer: User interface, supporting iOS (Swift), Android (Kotlin), desktop (TypeScript/Electron), CLI terminal
2. SimpleX Agent layer: Provides application-oriented advanced APIs to manage end-to-end encryption, connection lifecycle, and message queue rotation
3. SimpleX Client layer: Realize low-level communication of SMP protocol and connect relay router through TLS
4. SMP Router layer: stateless relay server (written in Haskell), provides a one-way message queue, mainly uses memory persistence.

3.2 Key Agreement Details

SMP(SimpleX Messaging Protocol)

-One-way Message Queue Protocol: Each queue is a one-way, ordered sequence of fixed-size (16KB) packets

-The queue is created by the receiver and shared to the sender via a one-time link

-Queue addresses are protected by encrypted credentials-sending credentials and receiving credentials are separated

-Messages are only cached in memory on the server side and are automatically deleted after timeout (default several days) or being taken away

-Server does not do user authentication -- only verifies message sending permission (based on queue credentials)

XFTP(SimpleX File Transfer Protocol)

-Separate protocol for large file transfers

-Each file block is assigned an independent address, suitable for efficient transmission of large files

-Also one-way, credential-based access control

2-Hop Onion Message Routing (Double Hop Onion Routing)

-The sender does not directly connect to the receiver's router

-The message is sent to the SMP route selected by the sender and then forwarded to the SMP route selected by the receiver

-The sender IP is only visible to the first hop route and the receiver IP is only visible to the second hop route

-Completely hide network layer metadata when used with Tor

3.3 Technology Stack Analysis

Note: The choice of Haskell as the primary language for the core protocol (~ 42% of the code volume) reflects the project's extremely high requirements for correctness and security-the strongly typed system and purely functional nature of the Haskell are naturally suitable for the implementation of cryptographic protocols.

4. Market positioning and competition analysis

4.1 Competitive Landscape

4.2 Differentiation Advantage

1. Unique zero identifier architecture :Signal needs mobile phone number, Session uses public key, Matrix needs domain name address-only SimpleX really does "without any user identifier". This is a qualitative leap in the theory of privacy protection.

1. Metadata protection far exceeds competition : Even Signal, its server still knows who is sending messages to whom (although the content is encrypted). SimpleX servers can't even determine who's communicating with whom.

1. The strongest anti-quantum encryption practice: SimpleX has achieved continuous post-quantum hybrid key exchange, while Signal has only used post-quantum algorithms in some of the ratchet steps, and other competitors have not yet been deployed.

1. Unique anti-spam architecture: Because there is no user identifier, spam messages are fundamentally impossible-no one can contact you without you actively initiating a connection.

1. Data sovereignty is fully owned by the user: All data is stored only on the user device, and the server only does temporary message caching. Users can switch to the self-built server at any time.

4.3 target user group

5. Business Model

5.1 Current Mode: Completely Free User Donation

SimpleX Chat is currently completely free and all features are open to all users. The project is maintained through the GitHub Sponsors and Patreon acceptance of user donations.

5.2 Future Mode: Community Credits (Community Points)

SimpleX are advancing an innovative decentralized sustainable business model-Community Credits:

┌──────────────┐     ┌──────────────────┐     ┌──────────────────┐
│   用户/赞助者  │────▶│  Community Credits │────▶│   服务器运营商     │
│  购买积分      │     │  智能合约（锁定资金） │     │   赎回积分获得报酬  │
└──────────────┘     └──────────────────┘     └──────────────────┘
                              │
                     零知识证明保护隐私
                     （购买-分配-赎回不可关联）

Core Principles:

-Private conversations and group communications permanently free (within fair use: up to 128 undelivered messages per contact, 21-day storage period, 1GB file storage for 2 days)

-Large Groups and Channels Use Community Credits to pay for server infrastructure

-Points non-tradable, non-transferable-excludes speculative properties.

-Use stable currency (USDT/USDC) to purchase, BTC/ETH/XMR and in-app purchases are supported in the future

-Server operators receive a maximum 70% payment fee, with the rest for network development and governance

-Use zero-knowledge proof to ensure that the purchase, distribution and redemption of points are not related to protect user privacy.

-Smart contracts are converted to autonomous immutable contracts after the test period and are not controlled by SimpleX Chat.

Roadmap:

5.3 Capital Model Analysis

SimpleX are raising development funds through the US Reg CF(Regulation Crowdfunding) compliant crowdfunding, emphasizing that it does not rely on a single large investor to avoid a "death switch"-in line with the concept of decentralization. At present (July 2026), it is in the stage of "testing the water temperature"(testing the waters) and has not yet officially accepted investment.

6. Pre-sales entry point

6.1 Why do customers need it?

Scenario 1: Government/Military Security Communications (Highest Match)

Pain point: The servers of existing communication tools (including Signal and Telegram) can obtain communication metadata-who contacted whom at what time. For classified government communications, the metadata itself may have more intelligence value than the content.

SimpleX Solution: The server cannot get any metadata because the user identifier does not exist at all. Even if a relay server is completely controlled by a hostile country, they can only see that "an IP has sent a packet to a queue" and cannot know the identity of the sender, the identity of the receiver, and the relationship between these queues and other queues.

Quantitative argument: A communication involves four independent servers, and an attacker needs to breach all four at the same time and perform traffic correlation analysis to infer a communication relationship, which is almost infeasible in terms of cost.

Scenario 2: Law Firm/Financial Institution Client Confidential Communications

Pain Point: Lawyer-client privileged communication (Attorney-Client Privilege) requires that the communication be kept absolutely confidential. A leak of sensitive communications within the bank about mergers and acquisitions, investment strategies, etc. could trigger allegations of insider trading. The servers of platforms such as WhatsApp/WeChat keep communication records and may be summoned.

SimpleX Solution:

-Messages are only stored on the user device, not retained by the server

-The burn-after-reading function ensures that sensitive information leaves no trace

Post-quantum encryption means that even if future quantum computers mature, historical communication records cannot be decrypted

• Competition Comparison Speech *: Although Signal is also end-to-end encrypted and open source, it requires mobile phone number registration and the server to master the communication map. Under a legal subpoena, Signal cannot provide the content of the message, but it can provide metadata about "when a mobile phone number communicated with a mobile phone number"-SimpleX cannot even provide this.

Scenario 3: Enterprise Internal Security Operations

Pain point: Security teams need secure communication channels when dealing with vulnerabilities and attacks. If the vulnerability details are discussed on the same platform, the platform itself may become the attack surface.

SimpleX Solution:

-Self-built relay server SimpleX network to build a completely isolated secure O & M communication channel

-CLI terminal client is suitable for use in a server operations environment

-Chatbot SDK for integration into SIEM/SOAR workflows

Scenario 4: Cross-border Communications in Sensitive Industries

Pain points: In scenarios such as multinational corporations, international trade, and cross-border legal services, communications may span multiple jurisdictions and face data monitoring and compliance requirements in different countries.

SimpleX solution: Users can freely choose the location of the relay server and switch at any time. The communication data is not stored on the server and there is no "data residency" problem.

6.2 Pre-sales Speech

Core selling point one sentence

"SimpleX is the only instant messaging system in the world where even the server does not know who the user is or who he is communicating with-more private than Signal and more reliable than P2P."

Technology Differentiation

7. Risks and Challenges

8. One sentence conclusion

• SimpleX Chat is currently the only encrypted communication platform in the world that realizes the design of "no user identifier". Its thoroughness in privacy protection theory surpasses Signal, Telegram and all mainstream communication tools. For enterprises, governments and sensitive industries with extremely high security communication needs, it is currently the most disruptive technology option, but network effects, financial sustainability and technology maturity are landing risks that need to be closely watched.**

• This article is based on the in-depth investigation of the SimpleX Chat project in July 2026. The data sources include GitHub warehouse, official documents, white papers and project official website. Star data are approximate at the time of the survey. *