computer science

SimpleX Chat

SimpleX Chat is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand SimpleX Chat rather than just read about it. In short: SimpleX Chat is a free and open-source cross-platform end-to-end encrypted instant messaging app and console application. The app does not require phone number, email address, or any other external identification.

Key takeaways

SimpleX Chat belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect SimpleX Chat to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of SimpleX Chat from memory before moving on to harder problems.

Reference excerpt

SimpleX Chat is a free and open-source cross-platform end-to-end encrypted instant messaging app and console application. The app does not require phone number, email address, or any other external identification. SimpleX applications are available for Android, iOS, Windows, macOS operating systems, and various Linux distributions.

History In July 2024, the American cybersecurity firm Trail of Bits conducted an independent security audit of the SimpleX Chat's cryptographic protocols. Following the arrest of Pavel Durov in France in 2024 many extremist groups fled from Telegram to SimpleX due to heightened privacy concerns.

Funding SimpleX Chat is developed by SimpleX Chat Ltd, a commercial company. The project began full-time development in 2021, initially supported by angel investors including Portman Wills and Peter Briffett. In July 2022, it raised approximately $370,000 in pre-seed funding, including from Village Global. In August 2024, SimpleX Chat announced a $1.3 million pre-seed investment led by Jack Dorsey, with participation from Asymmetric Capital Partners. The company has stated that user donations play a significant role, covering infrastructure costs and supporting development, with collective donations exceeding $25,000 as of 2023. In November 2025, the co-founder of Ethereum Vitalik Buterin donated 128 ethers to SimpleX Chat.

Russia In September 2024 the app was blocked by Russian authorities (Roskomnadzor). In September 2025, Tagansky court of Moscow fined the owning company SimpleX Chat Ltd. for "failure to fulfill the obligations of an instant messaging service provider," a violation of the law requiring every messaging application to collaborate with state authorities and, if requested, provide encryption keys for certain communications.

Features SimpleX Chat provides quantum-resistant end-to-end encryption for one-to-one chats, group conversations (called "secret groups"), and voice/video calls, using a double-ratchet protocol similar to Signal's, with an additional encryption layer per message. It requires no phone number, email, or personal details, instead using one-time invitation links, long-term invitation links (can be used more than one time) or QR codes for connections and temporary anonymous queue identifiers for message routing over the SimpleX Messaging Protocol (SMP). Unlimited creation of profiles is supported (Incognito or not). All user data is stored locally in an encrypted database on the device, with messages temporarily held on SMP relay servers and deleted after delivery. Additional privacy features include "Incognito mode," which generates a random profile name and prevents sharing of the user's actual profile name or image with new contacts, as well as a two-day expiration limit for file downloads, after which files become unavailable.

References

External links Official website simplex-chat on GitHub

Worked examples

Example 1 — a first encounter with SimpleX Chat

Start with the simplest possible case. Write down what SimpleX Chat claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to SimpleX Chat before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about SimpleX Chat ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of SimpleX Chat

In research: SimpleX Chat appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses SimpleX Chat in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: SimpleX Chat is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cross-platform free software, Cryptographic software, End-to-end encryption, so understanding it makes those chapters shorter.
In everyday life: Look for SimpleX Chat outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study SimpleX Chat in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what SimpleX Chat means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain SimpleX Chat out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is SimpleX Chat in simple terms?

Why does SimpleX Chat matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study SimpleX Chat?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on SimpleX Chat.