Fintech4 months engagement

Crypto Payment Gateway

Comprehensive manual QA for a decentralized, non-custodial crypto payment processing platform that enables merchants to accept digital currency payments with just 1% transaction fees. Built on Solana and Lithium blockchain infrastructure, the platform allows small businesses to accept crypto payments instantly without any crypto knowledge. We performed end-to-end manual testing of the entire payment lifecycle including merchant onboarding, payment link generation, blockchain transaction processing, wallet integrations, and multi-currency settlement flows across Solana and Lithium networks.

WebMobile WebBlockchainFunctional QASecurity TestingAPI Testing

Fund loss incidents

Critical bugs caught

100%

Fee accuracy

The Challenge

Irreversible Blockchain Payments

Transactions on Solana and Lithium are permanent. A single bug in payment routing or amount calculation could mean permanent fund loss for merchants or customers.

Non-Custodial Complexity

Funds flow directly between wallets without the platform holding them. Transaction verification and reconciliation had to work without centralized control.

Cross-Wallet Compatibility

Payment links had to work across Phantom, Solflare, Backpack, and other Solana wallets, plus mobile browsers and in-app wallet views with varying UX.

Multi-Language Payment Flows

8 languages supported across every screen. Payment confirmations, error messages, and merchant dashboards all required locale-specific validation.

Tools Used

Postman

Python

Playwright

TypeScript

Swagger

Postman

Python

Playwright

TypeScript

Swagger

Our Approach

How We Tested This Project

Payment Flow Mapping

We mapped every possible payment path from merchant link creation through customer wallet connection, transaction signing, blockchain confirmation, and final settlement. This produced 60+ distinct test scenarios covering happy paths, edge cases, and failure modes across both Solana and Lithium chains.

Blockchain Transaction Testing

Tested payment processing on Solana devnet and Lithium testnet before validating on mainnet with controlled small-value transactions. We verified transaction hashes, confirmation counts, fee deductions, and settlement accuracy against on-chain data using block explorers.

Wallet Integration Validation

Set up testing environments for each supported wallet provider including Phantom, Solflare, and Backpack. We tested connection flows, transaction signing, disconnection handling, and session persistence across desktop extensions and mobile apps.

Merchant Dashboard & Localization

Validated the merchant dashboard for real-time transaction tracking accuracy, settlement history, and fee reporting. Tested all 8 language versions end-to-end ensuring payment amounts, dates, and status messages displayed correctly in every locale.

Scope

What We Tested

01End-to-end payment flow from merchant link creation through customer payment to wallet settlement on Solana

02Lithium blockchain transaction processing including token transfers, fee deductions, and confirmation tracking

03Merchant onboarding flow including wallet connection, KYB verification, and dashboard setup

04Payment link generation with correct amount encoding, expiration handling, and QR code accuracy

05Transaction fee calculation accuracy at 1% across varying crypto amounts and token denominations

06Wallet integration testing across Phantom, Solflare, Backpack, and browser-based wallets

07Real-time transaction status updates on merchant dashboard with blockchain confirmation tracking

08Multi-currency payment scenarios including SOL, USDC on Solana, and Lithium native tokens

09Payment failure handling including insufficient funds, network congestion, and wallet disconnection mid-transaction

10Multi-language validation across all 8 supported languages for payment screens and merchant dashboard

11Mobile browser payment flow testing on iOS Safari, Chrome, and Android default browsers

12Edge cases around blockchain network congestion, stuck transactions, and RPC endpoint failover

13Merchant settlement reconciliation accuracy between blockchain records and dashboard reporting

14Security testing for payment link tampering, amount manipulation, and replay attack prevention

Impact

Results & Business Impact

Zero Fund Loss

First 5,000 merchant transactions processed with zero payment errors or fund loss incidents across Solana and Lithium chains.

11 Critical Bugs Caught

Including a Solana rounding bug that would have cost merchants 0.3% on transactions above $1,000.

100% Fee Accuracy

Transaction fee calculations validated to exact precision across all token types, amounts, and chain configurations.

28% Better Onboarding

Merchant onboarding completion rate improved after identifying UX friction points in wallet connection flow.

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