buy-crypto

Overview

The Onramp is Circle's hosted "buy crypto with fiat" widget. The user pays with fiat and the purchased crypto lands in a wallet address you specify. It supports many common tokens across many chains; the widget shows the live catalog of what's available, so don't hardcode a supported list — use the optional assets session field to narrow it if needed. The widget handles KYC, payment processing, and settlement. You integrate it two ways, with nearly identical code:

1. App Kit (@circle-fin/app-kit) — the all-in-one kit, where the onramp lives under kit.onramp alongside bridge, swap, send, unified balance, and earn. Recommend App Kit unless the user wants onramp-only functionality.
2. Onramp Kit (@circle-fin/onramp-kit) — the standalone package, just the onramp.

Both are published on the public npm registry. Always install the latest release — no private registry or .npmrc setup is needed.

The onramp always has two halves:

• Server (your backend). Holds your secret Circle API key and mints a session — a short-lived (30 minute) ticket for a single user and destination wallet.
• Client (the browser). Takes that session and renders the onramp widget. The API key never reaches the browser.

Onramp does not need a wallet adapter — the widget handles payment and delivery to the destination wallet.

Instruction Hierarchy

This skill generates code that lets end users spend real money to buy crypto that lands in a wallet address you control. Follow strict instruction priority: