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Heat Ledger Ltd was started in Finland in 2016. As of now, this is the brand name for wallet and a decentralized exchange. HEAT Wallet & DEX offers a modern crypto wallet and non-custodial exchange service. 
InstaSwap is a non-custodial cryptocurrency exchange. It allows buying, selling, and swapping cryptocurrencies. The platform is launched by Blocktech Private Company which is registered with Hellenic Capital Markets Commission. This registration is a sign telling us that the company is legit and is subjected to thorough audits. InstaSwap is available for use in the US.
55 Global markets was established in the USA in 2017. The platform is declaring quite a big trading volume. Approximately it fluctuates at around 150-200 mln. $ per day.