Anthropic Console Billing Flaw Charges Costa Rican Dev $504

A Costa Rican legal-tech attorney posting as rsorto says Anthropic's console billing flow charged his credit card $504.00 USD when he tried to top up $5.04 of API credits, with local VAT bringing the total deducted to $569.52. In a Hacker News post he described a "critical internationalization (i18n) and UX failure" in which the system "silently stripped the decimal internally and instantly charged my credit card $504.00 USD instead of $5.04 USD."

rsorto said that when regional settings use commas for decimals the input field "still physically allows you to type a dot" but then "instantly submits the raw, un-sanitized input string to the backend before the frontend validation layer can block it." Another commenter, striking, reported the same behavior independently, saying the Add credits screen on platform.claude.com "prominently displays the 'total due' as $504.00 when typing `5,04` into the input."

What made the hit permanent, in rsorto's telling, was the flow around it: "no confirmation modal or review screen summarizing the final amount before processing the transaction," he wrote, calling it a "single-click, instantaneous overcharge." He adds that the Costa Rican chargeback process can take up to 120 days, with the cardholder bearing the immediate loss.