@vrand.io/web

Verifiable randomness for web apps, in one line.

import { vrand } from "@vrand.io/web";

const r = await vrand.random(); // uniform float in [0,1) — proof-verified

One call = one on-chain request on VRAND, the verifiable randomness protocol on Solana: the user's wallet (Phantom/Solflare, or any wallet-adapter) signs one transaction, a bonded prover answers with a VRF proof, and the SDK verifies that proof locally before the promise resolves. A number from this API is never taken on an RPC's word.

Vocabulary you already know

await vrand.randomInt(1, 6);               // inclusive, bias-free
await vrand.pick(["red", "green", "blue"]);
await vrand.shuffle(deck);                 // Fisher–Yates, rejection-sampled
await vrand.coinFlip();
await vrand.weighted(prizes, [80, 15, 5]);

vrand.random((r) => spin(r));              // callback form

The bigger guns

// One request shaped into many outcomes of a single event — one fee:
const draw = await vrand.draw();
draw.int(1, 6); draw.pick(colors); draw.shuffle(deck);

// A batch of INDEPENDENT numbers — one fee per number, each its own proof,
// packed ~6 requests per signature:
const rs = await vrand.randoms(20);

// Sessions: one signature funds a local session key, then everything runs
// prompt-free until you end it (reclaims rent, sweeps the rest back):
const session = await vrand.startSession({ lamports: 0.05e9 });
await session.randoms(60);
await session.end();

// Verifiable draws with receipts anyone can re-verify:
import { deriveWinners } from "@vrand.io/web";
const winners = deriveWinners(draw.record.beta, entrants, 3);

// Get your request-account rent back:
await vrand.reclaim();

Why VRAND

• Locally verified, by default. The SDK re-derives the request's committed input from your own seed and re-checks the VRF proof before your code sees a value.
• Delivery has a price — for the prover. Provers post SOL bonds; declare an at-risk amount and a prover that misses its window pays you exactly that, via a permissionless slash.
• Bias-free shaping. Dice, shuffles, weighted picks and floats via rejection sampling — byte-identical Rust and TypeScript implementations pinned by cross-language golden tests.
• Honest terms. Before a wallet's first request, the protocol Terms of Use are shown in full and the wallet signs a standalone on-chain acknowledgment — explicit consent, once per wallet, never a rider on another transaction.

Live on Solana mainnet and devnet.

Zero-code embed

<script src="https://app.vrand.io/widget.js" defer></script>
<div data-vrand-widget></div>

Links

• Try it: app.vrand.io
• Docs: docs.vrand.io — start with Add to your app (2 min)
• Protocol: vrand.io

Apache-2.0.