To make the payment system robust and user friendly, decentralized based Scan and Pay system need to be

designed. This paper integrates the Unified Payments Interface (UPI) of India with the Solana-based Blockchain

to make the payment system decentralized. Solana offers a high throughput and low-cost based decentralized

infrastructure which is combined with the simple and reliable UPI system. So, the proposed system enables

cryptocurrency transactions linked to UPI while maintaining user friendliness, scalability, and regulatory

compliance. The designed method uses a secure architecture powered by smart contracts and modular design.

It offers a viable bridge between centralized financial networks and emerging Web3 ecosystems. Proposed

Among the innovations in this space, India's UPI has emerged as a remarkable one. It is introduced in 2016 by

the National Payments Corporation of India (NPCI). UPI allows for real-time bank-to-bank transactions through

a mobile interface, making it one of the most inclusive, scalable, and widely adopted payment platforms in the

world [2]. By February 2024, UPI had processed over 12 billion transactions in a single month, with services

extending across public utilities, retail purchases, and peer-to-peer payments [7, 11].

However, the UPI system, despite its remarkable domestic success, is inherently centralized [13, 14]. This

architectural constraint introduces different kinds of limitations, such as susceptibility to systemic failures,

restricted cross-border transaction capabilities, and dependence on centralized financial institutions. However,

Blockchain technology spearheading the Web3 movement by offering an alternative financial model

characterized by decentralization, immutability, and trustless peer-to-peer interactions [10]. Despite its promise,

innovative Proof of History (PoH) consensus mechanism, provides a robust infrastructure for implementing

scalable financial applications with very minimum latency and cost as compared to other platforms like

Ethereum.

The proposed model allows users to initiate crypto currency payments using their existing UPI. It links crypto

ecosystems through a middleware layer that facilitates identity resolution, transaction verification, and real-time

settlement on the Blockchain. This integration not only enhances financial efficiency but also helps in inclusion

by enabling even non-technical users to engage with Web3 applications.

The motivation behind this study is presented by using three key observations. First, as Blockchain-based

payment systems are matured matured technically, they remain disconnected from traditional financial

platforms that people trust and use daily. Second, the centralized nature of UPI makes it vulnerable to single

of the designed architecture with some transactions. Section 5 details the testing methodologies and results.

Section 6 compares the performance of Solana-based UPI and Non-Solana Blockchain-based UPI. Finally,

Section 7 concludes with a summary of findings and the future scope of the proposed system.

This section provides an overview of the technologies used and existing research related to the integration of

traditional financial systems with decentralized networks. In this part we have covered the evolution of the UPI

fundamental concepts of Blockchain technology, the design capabilities of the Solana Blockchain, and the

current landscape of related payment systems.

UPI has introduced features such as interoperability across different banking platforms, low-cost transaction

processing, and seamless integration with third-party apps like Google Pay, PhonePe, and Paytm. By February

2024, UPI had reached over 350 million active users, demonstrating its accessibility and scalability.

dependent on Indian banking systems. While this offers regulatory oversight and institutional trust, it also

introduces vulnerabilities related to downtime, censorship, and limited international use. As digital economies

become more interconnected, there is growing interest in extending UPI’s usability beyond domestic confines

through integration with decentralized technologies.

Blockchain is a distributed ledger technology that allows secure, transparent, and tamper-proof recording of

chain tracking, digital identity, and secure voting.

However, several challenges hinder Blockchain’s mainstream adoption. These include limited transaction

throughput, high network fees (especially in Proof-of-Work systems like Bitcoin and Ethereum), energy

consumption, and complex user interfaces. Moreover, regulatory uncertainties and lack of interoperability with

traditional systems remain unresolved issues.

Solana Blockchain

Solana is a high-performance, open-source Blockchain designed to enable fast, scalable, and low-cost

decentralized applications. It distinguishes itself through its unique Proof of History (PoH) mechanism—a

cryptographic clock that sequences transactions without requiring extensive consensus overhead. This

In addition to PoH, Solana incorporates several other mechanisms that enhance performance and developer

experience, including Tower BFT (Byzantine Fault Tolerant consensus), Gulf Stream (transaction forwarding),

and Sealevel (parallel smart contract execution). These features make it one of the few Blockchain platforms

Over the past decade, various efforts have emerged to bridge the gap between traditional financial systems and

decentralized networks. Early projects like Ripple and Stellar aimed to facilitate cross-border remittances using

Blockchain-based settlement. Ripple, for instance, collaborated with banks and payment providers to enable

instant international money transfers, though its consensus model remains permissioned and centrally

influenced.

Alharby M. [1] performed the studied on the Blockchain-Based smart contracts. The author analysed the smart

contract applications and its vulnerabilities. It is observed from the study that smart contracts suffer from

different vulnerabilities such as logic errors and re-entrancy errors. Kosba A. et al. in [8] proposed a Hawk

model based on Blockchain. The model uses the privacy preserving smart contracts and cryptography. The

model preserves the privacy quite efficiently but the limitation of the model lies in its complex cryptographic

generation smart contract application which is decentralized. The authors introduced the programmable

Blockchain and decentralized applications. The model has low throughput and high network congestion. Mettler

M. in [9] introduced the application of Blockchain in healthcare. The authors demonstrated Blockchain

transparency and data integrity applications. However, the model does not discusses about the payment

scalability and financial interoperability. A survey on security issues on Bitcoin is introduced by Conti M. et al.

in [4]. The authors discusses on Bitcoin but remain silent about the integration with the conventational payment

system. Smith B. in [15] discussed a unique digital architecture and its systematic transformation on financial

infrastructure. The authors remain silent about the practical implementation and testing in real life. Dinh T. et

al. introduced a Blockbench for performance evaluation using throughput, latency parameters in [5]. The authors

mainly focused on private Blockchain and does not discussed about public payment systems. Pierro G. [12]

use of Solana in the Blockchain needs further research.

scalability and high transaction issues. To overcome these, Solana based high-speed and low-cost transactios

are introduced by different authors, but these systems lack the integration with traditional payment system. To

overcome these, a secure hybrid framework integrating UPI with Solana Blockchain is required. This will take

Blockchain layer, and storage and key management layer. Each layer performs a specific function to ensure

secure communication, transaction processing, and reliable payment execution between traditional banking

systems and Web3 infrastructure. The proposed system architecture is shown in Figure 1.

The front-end layer acts as the primary interaction interface between users and the proposed payment system.

It is responsible for providing a simple and accessible environment through which users can initiate payments,

monitor transactions, and manage their digital wallets. The layer integrates cryptocurrency wallets such as

MetaMask and Phantom with UPI-based payment services, enabling users to interact with Blockchain

transactions without significant changes to their existing payment experience.

A QR-based payment mechanism is incorporated into this layer to simplify transaction initiation. Users can

performed. To support the UPI-based payment, QR code generation is also provided. Figure 4 shows the

transaction initiation request.

Due to the involvement of payment related transactions, two stage verifications are being carried out. Once the

initiation request is confirmed, it is again confirmed as shown in Figure 5.

receiver information, amount, status and timing of the transaction in Figure 6.

The proposed Secure UPI for Web3 framework is evaluated through a comprehensive testing methodology to

verify its functional correctness, performance efficiency, security strength, and practical usability. Since the

system integrates multiple components including the user interface, middleware services, UPI infrastructure,

and Solana Blockchain network, different levels of testing are performed to ensure that each individual

component and the complete system operate reliably under various conditions. The evaluation process includes

unit testing, integration testing, performance testing, security testing, user acceptance testing, regression testing,

and continuous monitoring.

The middleware layer is tested to verify the accuracy of REST API communication, request-response

processing, authentication mechanisms, and error-handling procedures. The interaction between UPI services

and Blockchain interfaces is validated using simulated API endpoints before deployment in the actual

environment. Similarly, smart contract functions deployed on the Solana Blockchain are individually tested to

ensure correct execution of operations such as payment initiation, fee distribution, and transaction completion.

Special test cases are considered for abnormal situations including insufficient balance, duplicate transaction

requests, invalid transaction parameters, and replay attempts.

The front-end testing process can be performed using tools such as Jest and React Testing Library, whereas

backend APIs can be tested using Mocha, Chai, and Postman. Blockchain-related functional verification can be

carried out using smart contract testing environments and Blockchain development frameworks.

are reflected on the user interface.

The interaction between the middleware and Solana Blockchain network is also evaluated to ensure proper

smart contract invocation, transaction submission, and response handling. The system verifies that Blockchain-

generated events, transaction confirmations, and failure responses are correctly interpreted by the middleware

layer. Furthermore, UPI integration testing is performed to validate fiat payment processing, transaction

synchronization, and handling of delayed or unsuccessful banking transactions.

Tools such as Postman are used for API-level integration testing, while the Solana Testnet environment is

utilized for validating Blockchain interactions. Container-based environments such as Docker can be used to

simulate integrated UPI and Blockchain services during the testing phase.