• IMPROVED All guides, the API reference and the developer tools now use the UC Card name and the official UC logo with "Card" as text.
• DOCS Rewrote the Sign in with UC Card guide: how it works, a full Node.js server example, linking existing accounts, and design guidelines with mockups (partner website on desktop and mobile, and the UC Card sign-in card).
• NEW Sign-in button generator (Tools → Sign-in button): choose a theme, label, language, shape and size, then copy the HTML and CSS.
• DOCS Code samples in Node.js, Python, Go, Java and PHP across the Quickstart, plus a signature-only function and a Postman pre-request script in Authentication.
• DOCS Flow diagrams redrawn as step-by-step charts, including a new callback verification diagram (sign → verify → 200 or 401 → retries).
• NEW Changelog page with an update alert in the header, and an RSS feed at /changelog.xml you can subscribe to.

Action: No code changes needed. API paths, headers, key prefixes (ok_test_ / ok_live_) and callback formats are unchanged.

• NEW 14 guides covering quickstart, console setup, Sign in (OIDC + PKCE), request signing, payments, callbacks, refunds, payouts, reconciliation, sandbox testing and go-live.
• NEW API reference generated from the Open Payment OpenAPI 3.1 spec, with a downloadable YAML file.
• NEW Signature generator and callback verifier tools.