Polar is a billing platform for software makers, made by Polar Software, Inc. It acts as a merchant of record, the company that legally sells a product in its own name for the maker, so it collects each payment and takes responsibility for sales tax, VAT, fraud, refunds and chargebacks (a chargeback is a payment reversed by the buyer's bank).
A maker sets up products in Polar: one-time purchases, subscriptions, or prices based on usage. Customers pay through a checkout link, an embedded checkout or the API. Polar calculates, collects and remits taxes in over 100 markets and pays out the rest. Usage billing records events such as AI tokens or GPU seconds, adds them up in live meters, and puts them on one invoice with the plan fee and prepaid credits. After a purchase, Polar can deliver benefits automatically: license keys, file downloads, GitHub repository access or Discord roles.
Polar is a hosted service, and its codebase is open source under the Apache 2.0 license. The free Starter plan charges a percentage plus a fixed fee on each transaction; paid monthly plans lower that rate.