Web3

Who it's for. dApps, wallet apps, DEX frontends, on-chain protocols, NFT marketplaces — anywhere the end user holds tokens in self-custody and the connected wallet is the source of truth. The user signs; you orchestrate; BRRR settles.

The defining characteristic of this vertical: non-custodial through the entire signing flow. The private key never leaves the wallet, and your application never holds user funds in transit.

Typical scenarios

• "Cash out" button next to a token balance. A wallet app surfaces a Deposit (off-ramp — moving from crypto to fiat) action wherever a user holds a supported token. One signature, EUR on a Holyheld card.
• Fiat-payout for swap or trade settlement. A DEX, perp protocol, or yield product routes the realized output token to a Deposit instead of returning it to the wallet — the user receives EUR directly.
• Creator / contributor payouts. A marketplace or DAO tool pays creators by Deposit-to-holytag, so the recipient receives spendable EUR rather than a stablecoin position.
• Top-up from card. A user funds a wallet from their Holyheld card balance via a Withdraw — useful for gas, for protocol participation, or for "send crypto" UX inside a non-custodial app.

Recommended stack

Need	Reach for
User signs from wagmi / viem / ethers / web3.js / Solana wallet adapter	SDK — handles signing flow, allowance, EIP-2612 permits
Cross-chain routing without per-chain RPC code	Orchestrate — bridges and swaps are computed by convertTokenToEUR/convertEURToToken
Display all of a wallet's supported tokens across networks	getWalletBalances
Resolve a recipient holytag before sending	getTagInfo
Read-only token metadata, prices, charts for richer UI	Web3 API

Almost every Web3 integration is SDK-first. The Web3 API is a complement, not a substitute — it's read-only display data that lives outside the user's signing flow.

Architecture at a glance

   ┌────────────────────────┐
   │   Your dApp / wallet   │
   │  (browser, RN, etc.)   │
   └────────────┬───────────┘
                │
                ▼
        ┌───────────────┐
        │   @holyheld   │
        │     /sdk      │   ← runs in the user's browser
        │               │
        │  signs with   │
        │  user's wallet│
        └──────┬────────┘
               │
               ▼
        ┌───────────────┐
        │     BRRR      │   ← cross-chain routing,
        │  Orchestrate  │     conversion, settlement
        └──────┬────────┘
               │
               ▼
   ┌────────────────────────┐
   │   Holyheld card  (EUR) │
   │   or recipient wallet  │
   └────────────────────────┘

You ship the SDK in the same bundle as your wallet-connect logic. There is no server component required for a typical dApp integration — the SDK API key is intentionally client-safe.

Where to start

1. Quickstart — pick the SDK
2. SDK Installation and Initialization
3. Web3 Providers — wagmi, ethers.js, web3.js, Solana wallet adapter
4. Examples — live multi-network reference apps

Where to next

• Deposit, Withdraw, Orchestrate — the three Core concepts hubs
• topup, requestOnRamp — the methods that execute each flow
• Supported Networks — current EVM and Solana coverage
• A live multi-network reference: holyheld.com/sdk/send