Trading foreign coins is legal
Referring to the U.S. Mint announcement https://www.usmint.gov/news/consumer-alerts/consumer/foreign-coins, businesses do not need the United States Mint’s permission to market foreign coins in the United States.
Banks are only willing to trade the largest denomination paper money issued by a dozen countries, however, there are more than 100 currencies issued by various countries in the world, so the foreign money left over from people’s travels has ended up becoming souvenirs or garbage. The Coin birds app is the first in the world to bring together travelers from all over the world on the same platform. Travelers can exchange foreign coins held by each other, and then the travelers can bring the foreign coins back to the country that issued the currency.
Coin Arbitrage
Coins are inconvenient to carry and transport due to their weight, so the smaller the denomination of the coin, the less popular it is.
When users sell foreign coins at discounts via the Coin birds app, foreign coins with smaller denominations require more discounts before they can be sold.
However, when travelers purchase foreign coins at a discount and bring them back to the issuing country, the purchasing power of these coins will jump back to their original denominations.
Therefore, we can use this feature to carry out risk-free arbitrage between currencies, denominations, and countries.
Outdated or Discontinued currencies
Some currencies that have ceased circulation, such as the currencies of EU member states before the euro was issued, can still be exchanged for euros at banks in the issuing countries.
Sometimes, currencies that have been discontinued have high collection value.
Reuse
Because coins are mixed with a variety of metals and have complex compositions that make it difficult to refine, foreign currencies will eventually become garbage over time. If the Coin birds app users reach a scale, this situation can be changed and foreign currencies can be returned to the country that issued the currency and used again.