Finance

SimpleTax is a small calculator for tax arithmetic. Its page describes it as free to download for iPhone, iPad, and Android, and states that it calculates before-tax, tax rate, tax amount, or total, entirely on the device. The site emphasises that the calculation works from whichever number you start with, uses currency-aware rounding, and keeps data local rather than sending it to a server. It is a single-purpose utility rather than a filing or accounting product: the page describes arithmetic, not returns or bookkeeping.

Ride Markets lets someone call a token on Solana and have funds back that call with real capital. Its page describes the arrangement as: call any token, funds back you, and you keep your share of the profit. The product is a markets and trading tool rather than a wallet or exchange. Its public page describes the mechanism in one line and does not publish a fee schedule or documentation at the time of collection.

Lemon Squeezy is a payments platform for software businesses that acts as the merchant of record. That means the company is the legal seller of record for each transaction, and it takes on the obligations that follow: sales tax and VAT registration, collection, and remittance in the jurisdictions where a customer buys. For a small software business selling internationally, that is the whole proposition. Instead of registering for VAT in the EU, the UK, and elsewhere as revenue grows, the seller handles one counterparty. The platform provides checkout, licence keys, subscription management, and a customer portal, and it pays out on a schedule. The cost is a higher percentage per transaction than a plain payment processor, because the merchant-of-record role absorbs tax and compliance work. Businesses with high volume sometimes move to a processor and handle tax themselves once the fee difference exceeds the cost of doing so.

Polar is a payments platform aimed at developers and open-source maintainers. Like other merchant-of-record services, it takes on sales tax and VAT obligations, but the product is shaped around the way developer projects sell: sponsorships, paid tiers for repositories, licence keys, and usage-based billing for API products. The integration is API-first with SDKs and a checkout that can be embedded, and there is a first-class GitHub integration for funding models where a sponsorship unlocks repository access or a private issue tracker. Usage-based billing supports metered events, which fits API products that charge by request. It is a younger platform than the established merchant-of-record services, so the ecosystem of integrations and the track record are shorter. Teams that want the developer-oriented billing model and are comfortable adopting an earlier-stage vendor are the natural fit; teams that need a long operating history usually choose a more established platform.

Uniswap is a decentralised exchange protocol on Ethereum and other EVM chains. Instead of an order book, trades execute against liquidity pools that anyone can deposit into, with prices determined by a formula rather than by matching a buyer to a seller. The design is what made it influential. A token can be traded as soon as someone creates a pool for it, without a listing process, and the pool's liquidity providers earn a share of the trading fee. The interface is a website, but the exchange itself is a set of contracts, so anyone can build another interface or route trades through it. The tradeoffs are inherent to the model. A large trade moves the price against itself, which is why aggregators split orders across pools. Liquidity providers face loss relative to simply holding the assets when prices diverge, and the user experience requires a wallet, gas, and an understanding of what a failed transaction costs.