Transak Integration for In-App Crypto Purchase

When trying to enable Transak integration for in-app crypto purchase, many face an unpleasant surprise: most on-ramp providers require redirecting the customer to an external site, which drastically reduces conversion. Transak is one of the few that allows embedding a purchase via a WebView widget while preserving the app's branding. But integrating into native iOS or Android projects is not always trivial: you need to correctly form the URL, sign partner requests with JWT, handle deep links and webhooks, and also comply with App Store Review Guidelines (Section 4.2 and 5.1). Over years of work (we've been on the market for over 5 years) we've hit our heads on these rakes and are ready to share a working recipe. This article details a guide to integrating Transak with code examples for Android (Kotlin) and iOS (Swift), as well as practical tips for setting up signatures and webhooks.

Problems That Integration Solves

Users often face high commissions, long KYC, or lack of support for the needed network. Transak solves this with a minimum commission of 0.5% on bank transfers, support for 130+ countries and 90+ cryptocurrencies, including Ethereum, BSC, Polygon, Solana. Partner JWT signing allows reducing the commission by an additional 0.2% and removing Transak branding. We guarantee the widget will fit your app's design via theme customization and hiding unnecessary menus. For a typical transaction of $500, the savings from partner signing can be $2.50 per transaction.

How We Do It: Integration Process

Forming URL for Transak Global

Base URL: https://global.transak.com

// Android — building the URL val params = mapOf( "apiKey" to transakApiKey, "walletAddress" to userWalletAddress, "network" to "ethereum", // ethereum, bsc, polygon, solana "defaultCryptoCurrency" to "USDC", "fiatCurrency" to "EUR", "productsAvailed" to "BUY", // BUY, SELL, or BUY,SELL "hideMenu" to "true", // remove Transak navigation "themeColor" to "1A1A2E", // hex without # "redirectURL" to "myapp://transak-callback", "exchangeScreenTitle" to "Buy USDC" ) val queryString = params.entries.joinToString("&") { (k, v) -> "$k=${URLEncoder.encode(v, Charsets.UTF_8)}" } val widgetUrl = "https://global.transak.com/?$queryString" 

For production — API key from dashboard.transak.com. Staging key (STAGING_TRANSAK_API_KEY) for testing: Transak test cards accept 4111111111111111 with any CVV.

Partner Signature (JWT)

On production accounts, Transak requires a signed JWT for authorized partners. Without it, the Transak widget works as public (with Transak branding). With partner signing — custom branding, lower commissions. For example, on an average order of $1000, the savings will be about $5 due to a 0.5% commission reduction.

// Server-side JWT generation (Node.js) const jwt = require('jsonwebtoken'); const payload = { apiKey: process.env.TRANSAK_API_KEY, walletAddress: userWalletAddress, userData: { firstName, email } // optional, for preKYC }; const token = jwt.sign(payload, process.env.TRANSAK_SECRET, { expiresIn: '1h' }); // Pass token to the app, add as &partnerOrderId={token} 

Handling Deep Links and Webhooks

After a purchase completes, Transak redirects the user to redirectURL. You need to configure Universal Links / App Links for iOS/Android for deep link integration. On the server side, verification of Transak webhooks using HMAC-SHA512 is mandatory — this protects against fake status updates. Key events: ORDER_CREATED, PAYMENT_DONE_MARKED_BY_USER, ORDER_COMPLETED, ORDER_FAILED.

const crypto = require('crypto'); app.post('/transak-webhook', (req, res) => { const signature = req.headers['x-transak-signature']; const payload = JSON.stringify(req.body); const expected = crypto.createHmac('sha512', process.env.TRANSAK_SECRET).update(payload).digest('hex'); if (signature !== expected) { return res.status(403).send('Invalid signature'); } // Process event const event = req.body.event; if (event === 'ORDER_COMPLETED') { // credit funds to user } res.sendStatus(200); });