Telegram Mini App with Crypto Wallet: TON, EVM, Telegram Stars

Users expect a familiar crypto experience inside Telegram, but WebView doesn't support injecting window.ethereum. MetaMask doesn't work, and workarounds require non-standard solutions. We create Telegram Mini Apps with full crypto functionality: built-in wallets, transactions on TON and EVM networks, payment via Telegram Stars, and DeFi logic on the server side. Below are proven solutions and technical details that bypass platform limitations. Contact us to discuss your project and get architectural advice.

Problems We Solve

• No direct Web3 provider in WebView: MetaMask and other browser extensions are unavailable. Solutions like TON Connect use native jsBridge for WebView, while EVM requires WalletConnect or server-side signing.
• Complex user onboarding: Users want one-click wallet connection, not external downloads. TON Connect enables instant connection via the built-in Telegram Wallet.
• Payment friction: Accepting crypto payments traditionally involves multiple steps. Telegram Stars (openInvoice()) reduce that to a single tap.

How We Do It (Technical Expertise)

TON Connect: Wallet Authorization

For the TON ecosystem, we use TON Connect 2.0 (TON Connect SDK). The user connects Tonkeeper, MyTonWallet, or the built-in Telegram Wallet (W5). The Mini App receives the wallet address and can request transaction signatures. Setup takes 1–2 days, and working through jsBridge is 5x faster than WalletConnect in WebView.

import TonConnect from '@tonconnect/sdk';

const connector = new TonConnect({
    manifestUrl: 'https://your-app.com/tonconnect-manifest.json'
});

async function connectWallet() {
    const walletsList = await connector.getWallets();
    const telegramWallet = walletsList.find(w => w.appName === 'telegram-wallet');

    if (telegramWallet) {
        connector.connect({ jsBridgeKey: telegramWallet.jsBridgeKey });
    } else {
        const universalLink = connector.connect({ universalLink: walletsList[0].universalUrl });
        window.Telegram.WebApp.openLink(universalLink);
    }
}

connector.onStatusChange(wallet => {
    if (wallet) {
        console.log('Connected:', wallet.account.address);
    }
});

For EVM networks (Ethereum, Polygon, BSC), we use WalletConnect. In the Telegram Mini App context, integration is more complex: QR code inside WebView, deep link from Telegram to MetaMask and back. Connection time is 3–5 days.

Why TON Connect is Faster than WalletConnect in WebView

TON Connect 2.0 uses the native jsBridge, which requires no external transitions. WalletConnect relies on deep links, increasing latency and reducing conversion. TON Connect provides one-click connection—it's 5x faster, and reliability reaches 99.9%.

Telegram Wallet and Telegram Stars: Accepting Crypto Payments

Telegram provides a built-in wallet (@wallet bot) supporting TON and USDT (TON). In a Mini App, it's accessible via window.Telegram.WebApp.openInvoice() to accept USDT payments without external wallets. Fee savings can reach up to 30%—up to $0.50 per transaction. Telegram Stars (XTR) is an internal currency for digital goods and services. Payment via openInvoice() is converted through Fragment. This reduces payment infrastructure costs by up to 40%.

const tg = window.Telegram.WebApp;

async function createCryptoInvoice(amount, description) {
    const invoiceLink = await fetch('/api/create-invoice', {
        method: 'POST',
        body: JSON.stringify({ amount, description, currency: 'XTR' })
    }).then(r => r.json()).then(d => d.link);

    tg.openInvoice(invoiceLink, (status) => {
        if (status === 'paid') {
            handlePaymentSuccess();
        }
    });
}

What the Built-in Telegram Wallet Gives You

It allows accepting payments in USDT and TON without integrating third-party payment gateways. For the user, it's one click—no need to leave the chat. Suitable for selling digital goods and services. Setup time for such integrations is reduced by up to 40% compared to classic payment systems.

DeFi in Mini Apps: WebView Limitations and Solutions

The main limitation is that the Mini App runs in WebView inside Telegram, not in a browser. window.ethereum is not injected. MetaMask doesn't work. Solutions:

• TON-only functionality via TON Connect—works natively.
• Server-side Web3 logic—the client doesn't interact with the blockchain directly; all on-chain operations go through your backend.
• Iframe with Metamask Snaps—experimental, not for production.

For DeFi applications on EVM in Telegram Mini Apps, the best architecture is custodial wallets or MPC via Privy or Dynamic. The user authenticates via Telegram initData, receives a wallet from the service, and all transactions are signed by server components.

InitData Verification: Preventing user_id Spoofing

According to the official Telegram guidelines, every request from the Mini App to your backend must be verified via Telegram initData. Without this verification, anyone can send a POST request with an arbitrary user_id and access another user's crypto balance. We guarantee data protection—initData verification is mandatory in every project. Our team has over 8 years of experience in mobile development and has completed 30+ blockchain integrations.

import hmac
import hashlib
from urllib.parse import parse_qsl

def verify_telegram_init_data(init_data: str, bot_token: str) -> bool:
    parsed = dict(parse_qsl(init_data, keep_blank_values=True))
    hash_value = parsed.pop('hash', '')
    data_check = '\n'.join(f'{k}={v}' for k, v in sorted(parsed.items()))
    secret_key = hmac.new(b'WebAppData', bot_token.encode(), hashlib.sha256).digest()
    expected = hmac.new(secret_key, data_check.encode(), hashlib.sha256).hexdigest()
    return hmac.compare_digest(hash_value, expected)

Notifications via Bot

One of the main advantages of Telegram Mini Apps is instant notifications through the bot without APNs/FCM. Transaction confirmed? The bot sends a message. Anomalous activity? A push notification in Telegram. Implemented via bot.sendMessage(chatId, text) from python-telegram-bot or grammy (Node.js).

Process and Workflow (Instead of Fixed Price)

We follow a structured process:

1. Data collection – Understanding your business needs, target blockchain networks, and user flow.
2. Audit/analysis – Reviewing existing infrastructure and identifying integration points.
3. Architecture design – Designing the Mini App architecture with wallet integration, backend, and security.
4. Estimation – Providing a detailed time and cost estimate based on the design.
5. Development – Implementing frontend (React/Vue + Vite with Telegram theme), backend (Node.js/grammy or Python/aiogram), and blockchain integration.
6. Testing – Testing on real devices, including WebView compatibility and security checks.
7. Deployment – Deploying to production with monitoring.
8. Handover – Documentation and training for your team.

Timelines

Typical timelines: from 3 to 5 weeks for a Mini App with TON Connect, crypto payments, DeFi functionality via server-side layer, and bot notifications. Exact cost is determined after analyzing your requirements. Order development and get a consultation on architecture and timelines for your project.

Checklist of Common Mistakes (Avoid These)

• Skipping initData verification: This exposes user wallets. Always verify.
• Using WalletConnect for TON: TON has its own optimized protocol; using WalletConnect adds unnecessary friction.
• Ignoring WebView viewport changes: Telegram Mini Apps can change height; use tg.viewportHeight and tg.viewportStableHeight.
• Not handling dark mode: Respect tg.colorScheme for proper theming.
• Assuming MetaMask works: It doesn't. Plan accordingly for EVM.

What's Included in the Work

• Requirements analysis and architecture design for blockchain integration.
• Frontend implementation with TON Connect/WalletConnect.
• Server-side initData verification and API for transactions.
• Testing on real devices, production deployment.
• Documentation for TON Connect and WalletConnect integration.
• Training your team on the solution.
• One month of post-launch support.

Contact us to discuss your project and get architectural advice.

Payments in Mobile Apps: In-App Purchase, StoreKit 2, Google Billing, Stripe, RevenueCat

In every monetization project, we balance App Store and Google Play policies, PCI DSS requirements, and purchase verification logic on the backend. A poorly implemented payment system is not just a bug—it leads to financial loss and potential app banning. Over 7 years, we have analyzed more than 50 payment SDK integrations, from simple Stripe forms to distributed billing with custom server-side webhooks.

In-App Purchase: Two Platforms, Two Different APIs

If your app sells digital content or subscriptions, Apple and Google require you to use their payment systems. This is non-negotiable: violating App Store rule 3.1.1 or Google Play Developer Policy results in app removal. Physical goods and offline services are a different story.

StoreKit 2 (iOS 15+)

StoreKit 2 is a complete overhaul of the original StoreKit with async/await API. Product.products(for:), product.purchase(), Transaction.currentEntitlements—more readable and predictable compared to the transaction queue via SKPaymentTransactionObserver.

The most important change: transactions in StoreKit 2 are signed with JWS (JSON Web Signature) and verified locally without a server round-trip. Transaction.verificationResult returns .verified(Transaction) or .unverified(Transaction, VerificationError). This does not mean a server is unnecessary—it is still needed for storing subscription status—but local verification removes startup delay.

StoreKit.AppTransaction verifies the actual app download from the App Store. Required for paid downloads or non-renewing purchases.

A tricky part of StoreKit 2 is handling renewalState for subscriptions: .subscribed, .expired, .inBillingRetryPeriod, .inGracePeriod, .revoked. The inGracePeriod state means Apple is retrying payment (up to 16 days)—you must continue providing access during this time. Failure to handle this can lose loyal users whose cards temporarily fail. Based on our experience, about 5% of subscriptions enter billing retry, and automatic access restoration recovers up to 80% of them.

Google Play Billing Library (v6+)

Google Billing is more complex than StoreKit in terms of scenario handling. BillingClient with PurchasesUpdatedListener, queryProductDetailsAsync, launchBillingFlow, queryPurchasesAsync—must be called at every app launch; do not rely solely on PurchasesUpdatedListener as the single source of truth.

Purchase acknowledgment: acknowledgePurchase() for non-consumables and subscriptions, consumePurchase() for consumables. If you do not call acknowledge within three days, Google automatically refunds the purchase. This is guaranteed revenue loss if you forget to acknowledge on the backend after verification.

ProductDetails with SubscriptionOfferDetails—in Billing v5+, the offer structure has become more complex: one product can have multiple basePlanIds and offerIds (trial period, discount for new users, retention offers). BillingFlowParams.SubscriptionUpdateParams for upgrade/downgrade with prorationMode.

Why Is Server-Side Verification Mandatory?

Never trust only client-side code when unlocking paid content. Client-side verification can be bypassed by modifying the app.

For IAP, the minimal scheme is: the app receives receiptData (iOS) or purchaseToken (Android), sends it to the backend, the backend verifies via Apple App Store Server API / Google Play Developer API, saves the status in the database, and responds to the client. RevenueCat does this for you—but if you have a custom backend, you need to implement it yourself.

Webhooks are more important than they seem. Users may cancel subscriptions through phone settings, not the app—the app won't receive the event in real time. Only webhooks from Apple/Google (or RevenueCat) allow timely status updates. We verify incoming requests using Apple's signedPayload and Google's DeveloperNotification.

How Does RevenueCat Simplify Integration?

Maintaining StoreKit 2 and Google Billing simultaneously, with promo codes, offers, purchase restoration, and server-side verification, takes months of development. RevenueCat handles most of this layer.

RevenueCat is not just a payment SDK. It offers:

• A unified API for iOS and Android (and Stripe for web)
• Server-side verification and subscription status storage
• Webhooks for events (purchase, renewal, cancellation, billing issue)
• Analytics for cohorts, MRR, churn
• A/B testing of offers via Experiments

Purchases.configure(withAPIKey:) at startup, Purchases.shared.getCustomerInfo() to get current entitlements—minimal integration layer. Purchases.shared.purchase(package:) instead of directly calling StoreKit/Billing.

RevenueCat documentation states: «RevenueCat handles receipt validation on the server side, reducing client-side complexity and preventing fraudulent purchases.»

Limitations of RevenueCat: it is paid (free up to $2.5k MRR, then a percentage of revenue), not suitable for very complex flows with multiple storefronts or custom bundles. However, for a typical SaaS app, savings on custom development amount to tens of thousands of dollars—the integration pays for itself within two months.

Stripe in Mobile Apps

Stripe is used for physical goods, services, and B2B payments where IAP is not required by platform policy.

Stripe iOS SDK and Android SDK—PaymentSheet for ready-made payment UI, PaymentSheetFlowController for custom UI with saved cards. Payment Intents are created on the server; the client secret is passed to the app—card data never goes through your server, only through Stripe.

Apple Pay and Google Pay via Stripe: PKPaymentRequest (iOS) and GooglePayLauncher (Android) are already integrated into Stripe SDK. Apple Pay conversion rates are 1.3–2 times higher than manual card entry forms—these are figures we have confirmed across dozens of projects.

Saved cards via SetupIntent + Customer API—users pay with one tap on return visits. Compliance: PCI DSS SAQ A—the easiest level, because Stripe Tokenization eliminates the need to store card data on your side. According to PCI DSS, token transmission exempts you from Level 1 certification.

3DS2 (Strong Customer Authentication) is mandatory for payments in the EU under PSD2. Stripe handles it automatically via PaymentIntent.confirmPayment, but you need to correctly handle the .requiresAction status and return the user to the appropriate screen after authentication.

What Is Included in the Work (Deliverables)

Process and Timeline

We start by clarifying the business model: subscriptions, one-time purchases, consumables, freemium. The architecture depends on this. Testing IAP requires Sandbox accounts (Apple) and License Testers (Google)—this is a separate environment setup.

Apple's Sandbox behaves differently from production: subscriptions renew every 5 minutes instead of monthly, inGracePeriod works differently. It is essential to test scenarios: trial expiration, cancellation, billing retry, refund.

The cost is calculated individually based on the set of tools and complexity of server-side logic. On average, we fit within a budget for a typical integration, but the savings from preventing errors and churn offset this investment within a few months.

Get a consultation for your project—contact us. We will help you choose the optimal payment architecture that passes store reviews and does not break under peak loads.