How to Build an App Like Telegram: The Engineering Playbook

Telegram hit 900 million monthly active users in 2024 without a single dollar in revenue from most of them. The product is free. The engineering is genuinely impressive. And if you are building a communication platform for a specific audience -- enterprise teams, a regulated industry, a niche community -- you do not need to replicate all of it. You need to understand which parts matter for your use case.

This guide breaks down what Telegram actually is under the hood, what to build for v1, and where the real engineering costs land.

What Telegram actually is

Most people think of Telegram as "WhatsApp but more private." That undersells it. Telegram is three distinct products sharing a codebase:

Personal messaging. 1-on-1 and small group chats with cloud-based message storage. Unlike WhatsApp, messages are stored on Telegram's servers, not your device. Every device you log into shows your full message history immediately.

Channels. One-to-many broadcasting. A single account publishes to an unlimited subscriber list. No replies, no group dynamics -- pure broadcast. This is closer to a newsletter platform than a messaging app.

Bots. Programmable agents that respond to commands and messages. The Bot API is what turned Telegram into a platform. Developers build everything from customer support bots to full e-commerce flows inside Telegram.

When you say you want to build "an app like Telegram," you need to decide which of these three products you are actually building.

Cloud storage vs. device storage: the core architectural choice

This is the most important decision you make on day one.

WhatsApp stores messages on your device. Telegram stores messages in the cloud. Each has consequences:

Cloud storage (Telegram's approach) means:

• New device login shows full message history instantly

• Messages survive phone replacement or loss

• Server storage costs grow with every user and every message

• You can access messages from any device

Device storage (WhatsApp's approach) means:

• No server-side message retention (lower storage costs)

• Messages lost if device is wiped without backup

• Multi-device sync requires a different protocol entirely

• More private by default (server cannot read messages)

For business communication tools and community platforms, cloud storage is usually the right choice. Users expect their history to be there when they log in from a new device.

V1 features: build only these

User registration

Phone number verification via SMS OTP is the industry standard for consumer messaging apps. It prevents fake account creation and provides a natural contact discovery mechanism.

For enterprise products, email + SSO (Google, Microsoft) is often a better choice. Phone numbers create friction in corporate environments where IT manages accounts.

1-on-1 messaging

Text messages with three delivery states: sent (server received it), delivered (recipient's device received it), and read (recipient opened the chat). Keep v1 to text, images, and files up to 20MB. Voice messages are popular on Telegram -- include them only if your target users clearly want them.

Group chats

Groups with up to 50 members. Admin roles (who can add/remove members). Basic moderation (remove member, mute). Group photo and name.

Keep group size at 50 for v1. Telegram's 200K-member "supergroups" require a fundamentally different fan-out architecture. Build for 50, architect for growth.

Push notifications

The most important background feature. When the app is closed, users still need to receive message notifications. Firebase Cloud Messaging (FCM) handles Android. Apple Push Notification Service (APNs) handles iOS. Both can be managed through a single library.

Message search

Search your own message history by keyword. This is a standard expectation in 2026. PostgreSQL full-text search handles it at MVP scale. Elasticsearch becomes relevant above 100K active users.

User discovery by username

Users should be findable by a unique username without sharing a phone number. This matches Telegram's own model and reduces friction for privacy-conscious users.

What to skip in v1

• Channels. Broadcasting to large subscriber lists is a different product with different infrastructure requirements. Ship it after the core messaging loop is proven.

• Bot API. Building a programmable bot platform is a substantial project on its own. If bots are your core use case, they should be the product -- not an add-on.

• Secret Chats (E2E encryption). More on this below.

• Voice and video calls. WebRTC is complex. Use a third-party service (Agora, Daily.co) if calls are needed at all for v1.

• Polls and quizzes. Nice to have, not core.

• Scheduled messages. V2 feature.

• Sticker packs. High engineering effort for low product impact at the MVP stage.

The encryption decision

Telegram's "Secret Chats" use end-to-end encryption. Regular Telegram chats -- including all group chats -- use server-side encryption. Messages are encrypted in transit (TLS) and at rest, but Telegram's servers can technically read them.

This is not a privacy failure. It is a deliberate product choice that enables cloud storage and multi-device sync.

For your v1: TLS in transit plus AES-256 encryption at rest is almost certainly sufficient. True E2E encryption requires per-conversation key pairs, key exchange protocols (Diffie-Hellman or Signal Protocol), and key storage that cannot be server-side. That adds 4-8 weeks of engineering and $30K-$50K to your budget.

Build E2E encryption in v1 only if your use case requires it: healthcare (HIPAA), legal, financial services, or any context where regulatory compliance demands it.

The hard engineering problems

Message delivery guarantees

Every message needs a guarantee: the server acknowledged receipt, the recipient's device received it, and the recipient read it. This requires a client-side acknowledgment system. When a client goes offline, the server queues undelivered messages. When the client reconnects, it syncs the queue and sends acknowledgments.

Getting this right prevents duplicate messages, missing messages, and incorrect delivery status -- the failure modes users notice immediately.

Real-time presence

"Online" and "last seen" status seem trivial. They are not. Each server instance only knows about clients connected to it. When user A (on server 1) opens a chat with user B (on server 3), server 1 needs to know whether user B is online right now.

This requires either a centralized presence store (Redis is standard) or a gossip protocol between servers. At small scale, Redis works fine. At Telegram's scale, it is one of the hardest distributed systems problems.

Multi-device sync

If a user reads a message on their phone, the laptop should show it as read too. If they delete a message on one device, it should disappear on all devices. This requires a sync state machine that tracks message state per device and reconciles differences when devices reconnect.

Media compression and delivery

Users send full-resolution photos. Delivering them at full resolution to every recipient wastes bandwidth and storage. You need server-side compression at upload time, multiple resolution variants for different display contexts (thumbnail, preview, full), and CDN delivery from the edge closest to each recipient.

Offline message queuing

When a recipient is offline, their messages queue on the server. When they reconnect, they need to receive messages in the correct order, without duplicates, even if they were offline for hours or days. This sounds simple and is routinely underbuilt in messaging MVPs.

Should you implement E2E encryption in v1?

Probably not. Here is the math:

Without E2E encryption (server-side encryption + TLS): standard implementation, well-understood, adds no timeline or budget pressure. Appropriate for most enterprise tools, community platforms, and productivity applications.

With E2E encryption (Signal Protocol or MTProto): 4-8 additional weeks, $30K-$50K additional cost, significantly more complex key management, and a harder debugging environment (you cannot inspect encrypted messages on the server). Required for regulated industries and privacy-first consumer products.

Make the decision based on your users' actual requirements -- not because Telegram has it.

Tech stack

Elixir/Phoenix is worth considering for the real-time backend. Its actor model and fault tolerance are well-suited to WebSocket-heavy applications. Node.js with Socket.io is the safer choice if your team does not have Elixir experience.

Cost to build

Monthly operating costs after launch: $3K-$10K for a 10K-50K active user base, depending on message volume and media storage. Media storage costs grow linearly with users and file volume -- plan for it.

Use cases beyond consumer messaging

Telegram-like architectures show up in products that are not messaging apps:

Enterprise secure communications. Teams with security requirements who cannot use consumer apps. On-premises deployment options become a product differentiator.

Field team coordination. Construction, logistics, healthcare field workers. Group channels for shift updates, 1-on-1 for coordination. Bot integrations for job dispatch.

Customer service automation. Bot-first product where users interact with automated workflows and escalate to human agents. The messaging interface is the product; the chat is the channel.

Community management. Topic-organized groups, announcement channels, moderated discussions. The channel/group distinction matters here more than in personal messaging.

How RaftLabs approaches this

When a client says they want to build "a Telegram for our industry," the first questions are product questions, not engineering questions.

Which of the three Telegram products do you actually need? Most clients need the messaging core and nothing else. Some need channels for customer communication. A handful need bot infrastructure for automation.

What is your compliance context? Healthcare and legal clients need E2E encryption or at minimum rigorous access controls and audit logging. Enterprise clients often need SSO, admin visibility, and message export. Consumer apps need neither.

What is the network model? How do users find each other -- by phone number, email, username, or through your existing user base? This shapes onboarding entirely.

We build messaging infrastructure as part of larger products: field service platforms, healthcare coordination tools, enterprise productivity applications. We do not build consumer messaging apps to compete with Telegram.

If you are building communication as a feature of a larger product, start with a scoping call.