MINE: NFT Marketplace for title deeds of physical properties (cars, motorcycles, boats, among others).

MINE is a platform that allows transactions without the need of buyers and sellers physical presence in the places or countries where the operation is carried out. With purchase / sales transactions paid in cryptocurrencies, protected purchases for the security protection of both the buyer and the seller.

This solution is based on Web3 technologies, through the creation of a DApp deployed on the Ethereum Blockchain.

It was made by The GOF5 (Gang of Five) during Platzi’s Ethereum Developer Program 2022.

NFT Marketplace Features

  • Users (buyers, sellers) must connect their Wallet to:
    • Register.
    • Authenticate.
    • Register new goods for sale.
    • Buy goods.
  • Additionally, they must have contact information to negotiate goods and prices:
    • ID / Driver’s License.
    • First name.
    • Last name.
    • Phone number.
    • Email.
  • There will be a public display of the goods. Observers also need a Wallet to query and view.
  • Goods will be displayed by categories.
  • The currency to display the prices of the Goods will be US Dollar and the official exchange currency will be the ETH (the Ethereum cryptocurrency).
  • Initially it will only be available in Medellín, Colombia.
  • A commission will be associated with each of the NFTs registered in the DApp so that each time this NFT is transferred it sends a percentage to the owner of the Smart Contract.
  • A commission will be charged for each sale made.

What problem does the project solve?

Has it happened to you that you want to buy or sell a vehicle outside your location, and you don’t find the people or tools necessary to perform the transaction?

Are you tired of Marketplaces on social networks that do not deliver the true information of what you are looking for, and if you offer a product, it is not given enough visibility?

Are you tired of paying high commissions for bank transfers to pay for goods?

How the NFT Marketplace solve it?

MINE: A NFT Marketplace that allows transactions without the need for physical presence of buyers and sellers in the localities or countries where the operation is carried out, with purchase / sale transactions paid in cryptocurrencies, with protected purchases for the protection of the security of both the buyer and the seller.

This solution is based on web3 technologies, through the creation of a DApp deployed on the Ethereum Blockchain.

Impact on Society

  • In Latin America there is no NFT Marketplace for physical goods like this.
  • Time saving. Buyer and seller can make transactions without leaving home/office.
  • Trust and credibility between the parties: because the Goods are audited by certified experts, and these Experts can be chosen by the buyers.
  • Do not go through banks: thus, avoiding intermediaries.
  • Avoid high fees for large transactions and/or international transfers.

Value Added to Web2

  • Decentralization:
    • Business logic is a Smart Contract.
    • The App Frontend cannot be censored.
    • The data is not under the control of the developers.
    • The Blockchain where the Smart Contract is deployed is Ethereum.
    • The Frontend is built an open source.
  • Traceability of goods, transactions, signatures of involved.
  • Transparency.

NFT Marketplace user types


  • Puts the money from the purchase of the Good.
  • You must have the funds in your Wallet.
  • Pay the tax.


  • Owner of Good.
  • It must cover the expenses of the publication of the contract and the NFT mint (issuance), with the characteristics specified below.
  • Pay the Expert’s fee or certification.

Experts / Certifiers:

  • Certify the validity of the Good, then it can be sold.
  • Sign the transaction when the Owner Property is changed on a physical world.
  • Charge transaction fees.
  • Digital Document Creation Service: If a product does not have a title deed, it is generated.
  • The expert is legally responsible for the transaction.


  • He/she performs the legal property transfer in the real world.
  • At the digital level, sign the transaction with his/her address / Wallet.
  • Receive taxes.

Administrator (our Wallet):

  • Charging commissions.
  • Send to execute transferFrom from the buyer’s account to the seller’s.

NFT Features

The NFT will be the picture of the Good.


  • Description, categories, photo arrangement.
  • Apart from the main photo, there may be additional photos (example: the motorcycle, vehicle, or boat from different angles).
  • A section of photos only visible to the seller and the buyer who already gives their approval of purchase intention, and the experts. One or more of them will be the ownership legal document.

Possible problems

  • Conversion from ETH to USD/COP or other currency, and vice versa.
  • Duplicate NFT (that the same Good for sale is published several times).
  • More than one owner.
  • Penalties in case of fraud in the properties.

NFT Marketplace Architecture


  • The goods may only be sold when they are verified by a certified Expert. Experts must have an official certification to exercise their functions, validated by the regulatory entities in the region where they carry out their activities. For this, a badge will appear when displaying the Good indicating such condition.
  • The Experts will be responsible for auditing and certifying that the Goods exist and are in order. On them will fall the legal responsibility of legitimacy of the Goods. They will be able to interact with the system using their Wallets and earning a commission for purchases and sales.
  • Purchase / sale of real estate: real estate, commercial premises, among others adding to the Metadata address, GPS coordinates, photos of exteriors and interiors.
  • Purchase/sale of virtual assets: plots in the Metaverse, NFT works of art, among others.
  • Purchase / sale of Jewelry.
  • Auction of goods and assets.
  • Expand the operation to other Latin American countries and regions.
  • Use as a means of payment Stable Coins as Tether (USDT).
  • Additional photos in the Metadata of the Goods, as well as private photos.
  • Encryption of sensitive user data (PII) stored in the IPFS.
  • Display prices in local currency (e.g., COP).

Tools used


  • ReactJS
  • Web3.js (Wallet connection)
  • Chakra-UI (templating)
  • Mocha (testing)
  • HTML
  • CSS
  • JavaScript
  • VS Code (coding & peer programming)


  • Solidity
  • Hardhat
  • Open Zeppelin
  • Chain.link (exchange rate integration between ETH – and USDT)
  • Chai (testing)
  • VS Code (coding & peer programming)


  • Metamask (Wallet + authentication + Ethereum provider)
  • IPFS / Infura (data persistency)
  • Goerli (test net)
  • Goerli PoW Faucet (faucet)

NFT Marketplace Repository

NFT Marketplace Live Demo

Developer Team

Eimer Wilfer Castro Hincapié
🔗 https://github.com/ewcastroh

Carlos J. Ramirez
🔗 https://github.com/tomkat-cr

Javier García
🔗 https://github.com/stratoff

José Valentín Salina
🔗 https://github.com/josevsalina

Fidelina Arteaga
🔗 https://github.com/fidelinaarteaga

How did they solve it as a team?

Our call as a team was quite spontaneous. Eimer summoned Carlos, then both summoned on channel #General of the Discord of the #EthDevProgram challenge and then Javier, José and Fidelina appeared. Eventually, the group adopted the name GOF5 (Gang of Five).

There was a spirit of equality among us, and everyone’s interventions were respected. This came naturally from the beginning.

We started meeting to see what ideas we had. Each one presented his idea, and with a mastermind we were adding details and other things that were appearing.

We let the idea land for a day or two, and then it was put to a vote. No one lobbied, no advertising, no lobbying. No votes were bought. It didn’t matter whose ideas they were either.

We agreed to start doing daily meetings to achieve the goals. The first meetings last less than 1 hour to put the mastermind to work and shape the project.

After establishing the Jira board, starting to create and assign tasks in the Backlog, we meet daily in Stand Ups of 15-20 minutes to follow up, seeing what was done the day before, what is planned to be done today and the existence of some blockage.

We started working on the Whitepaper, in somewhat marathonic meetings (3-5 hours) but very productive. We delimit the project, describe actors, procedures, and above all, the conceptual part: the history, the impact, added value of Web 3 on doing it in Web 2, possible problems, legal framework, pitch, technologies, among other things.

At one point we lost faith in the project, because we came to think that the conceptual part regarding the advantages of the Blockchain vs the current applications of Web 2.0 and the complexity of the legal issues involved in the transfer of goods did not make much sense, however, we managed to establish well the added value that we can give by solving the problem with our platform that would facilitate and give security in the user’s purchase / sale of goods.

In another marathonic session we defined the 90-second Pitch Elevator, the presentation of the project, the logos for the DApp and the group, and a model with the design of the screens.

With the agenda for the next 2 weeks clearer, we started working in teams for the Frontend, Backend and Operations.

Our official slogan: “Let’s solve with what we have“.

Work Methodology, Monitoring and Deliverables

We established Scrum as an agile work methodology and Jira as a tool to follow up.

We established 1-week Sprint starting August 23, 2022.

It was done in 2 Sprints and at the end of each one there was a deliverable:

  1. 2022-08-30 – MINE Project White Paper.
  2. 2022-09-06 – MVP (Minimal Viable Product).