Please describe your proposed solution

Consumers want to pay in crypto. Merchants need a way to accept crypto payments without the volatility risk. Stablecoins need a way to fulfill their potential as means of exchange.

We are going to implement a payment widget similar to Stripe or PayPal that merchants can add to their websites. Consumers pay in ADA or MOD (Milkomeda Djed Osiris Dollar). Merchants receive in MOD.

Behind the scenes, the payment widget calls the Milkomeda Djed Osiris contract to automatically mint MOD for the merchant when the consumer pays with ADA.

This project is part of Google Summer of Code. The detailed proposal that has been accepted by the Google Summer of Code program is available here (https://docs.google.com/document/d/1D0_3Q6_gTlzrBlnGagzJXHt0Sa6A94FfXlMwu7Beizo/edit).

We include below the sequence diagrams and figma designs that explain how the StablePay widget will work. Please visit the link above for more details.

Please define the positive impact your project will have on the wider Cardano community

For a cryptocurrency to be a currency, it needs to perform the functions of money: store of value, unit of account and means of exchange. Despite more than a decade, the cryptocurrency industry still hasn't managed to make a cryptocurrency that is widely accepted for payments "in real life". Stablecoins solve part of the problem and we have Djed on Cardano already. But the other part of the problem is payments infra-structure, in a format that merchants are used to. This other part of the problem is what we will be addressing with this project. In doing so, we will pave the way for Cardano to function as a payments platform. Members from the Cardano community will be able to include the open-source and free StablePay widget in their merchant websites and start receiving payments in ADA that are automatically converted to stablecoins. Therefore, we expect the output of this project to generate lots of opportunities for the Cardano Community.

What is your capability to deliver your project with high levels of trust and accountability? How do you intend to validate if your approach is feasible?

Dr. Bruno Woltzenlogel Paleo (a.k.a. Zahnentferner) is the founder of the Djed Alliance and of The Stable Order. He is the main author of the Djed paper and a member of Djed's original R&D team, which implemented both Agenor (deployed as SigmaUSD on Ergo) and Belus (deployed as Milkomeda Djed Osiris on Cardano's EVM Sidechain Cardano). Therefore, he has deep knowledge of the project that underlying stablecoin protocol with which StablePay will have to interact. Furthermore, during his academic career, he has already received and managed more than 1 million USD in research grants in several countries and always achieved the goals of the proposed projects.

Tanya Srinivas, Anshdeep Singh, Roshan Raj Singh, Yogesh Agrawal have been contributing to the Milkomeda Djed Osiris repos for several months and are therefore already familiarized with the code they have to interface with in StablePay.

To know more about our organization as a whole, check the following links:

• <https://docs.stability.nexus/>
• <https://medium.com/DjedAlliance>
• <https://news.stability.nexus/>
• <https://x.com/DjedAlliance>
• <https://x.com/StabilityNexus>
• <https://linkedin.com/company/stability-nexus>
• <https://t.me/StabilityNexus>
• <https://discord.gg/YzDKeEfWtS>
• <https://github.com/StabilityNexus>
• <https://djed.one/>
• <https://github.com/DjedAlliance>
• <https://eprint.iacr.org/2021/1069>

What are the key milestones you need to achieve in order to complete your project successfully?

Milestone 1: Milestone Outputs: design in figma or similar tool.

Acceptance Criteria: the figma design should show the StablePay widget.

Evidence of Milestone Completion: link to design files.

Milestone 2: Milestone Outputs: implemented StablePay widget frontend.

Acceptance Criteria: the widget should be embeddable in a webapp.

Evidence of Milestone Completion:

• link to a demo webapp where the widget is embedded.
• link to source code.

Milestone 3: Milestone Outputs: integration of the StablePay widget with the Djed contract.

Acceptance Criteria: the widget should be able to create and submit transactions that interact with the Djed contract.

Evidence of Milestone Completion:

• link to a demo video showing the payment widget being used and transaction appearing on the blockchain explorer.
• link to source code.

Milestone 4: Milestone Outputs: implementation of callback, allowing the widget to inform the website where it is embedded that the payment was successful.

Acceptance Criteria: the widget should be able to trigger changes in the website where it is embedded when a payment succeeds or fails.

Evidence of Milestone Completion:

• link to a demo video showing the website being notified of a successful payment.
• link to source code.

Final Milestone: Milestone Output: merchant dashboard, a dapp where the merchant can see payments that have been made.

Acceptance criteria: the merchant dashboard should fetch from the blockchain all payments that the merchant has received via StablePay.

Evidence of Milestone completion:

• Screenshots of the dashboard.
• Link to the source code.
• Link to the deployed dashboard dapp.

Who is in the project team and what are their roles?

Dr. Bruno Woltzenlogel Paleo (a.k.a. Zahnentferner) - Djed Protocol engineer, software architect, mentor.

Tanya Srinivas, Anshdeep Singh, Roshan Raj Singh, Yogesh Agrawal - Software developers responsible for frontend, backend, smart contracts, testing and devops of the StablePay payment widget.

Please provide a cost breakdown of the proposed work and resources

Assumption: 1 ADA = 0.4 USD .

According to Indeed (https://www.indeed.com/career/software-engineer/salaries), the average base salary of a software engineer, excluding benefits is 22000 ADA per month. We estimate that we need 4 months to complete this project.

5 engineers for 4 months would cost, on average, 5 x 4 x 22000 ADA, which is equal to 440000 ADA. We are requesting only 200000 ADA, which is the maximum amount in the "Cardano Developers: Open" category. All requested funds will be used for technical R&amp;D tasks of the StablePay payment widget.

No dependencies.

We are fortunate to have the support of (though not a dependency on) Google and AOSSIE (the Australian Open Source Software Innovation and Education association) for this project through the Google Summer of Code program.

How does the cost of the project represent value for money for the Cardano ecosystem?

According to our estimates, based on average values by Indeed, we are going to complete this project for only 45% the cost that it would normally have.