What version of Node.js do I need?

Node.js 18 or newer. The quickstart relies on the built-in global fetch, so no extra dependencies are required.

Do I need to install any dependencies?

No. The quickstart uses the built-in fetch in Node 18+ — zero npm installs. If you want a typed wrapper later, the official @provableio/sdk on npm covers every endpoint.

How do I generate random outcomes from Node.js?

Call fetch on https://api.provable.io/api/ints (or /api/floats) with the clientSeed, count, min, and max as query parameters. The JSON response contains the outcome array plus the serverHash you'll publish for verification.

How do I verify an outcome later from Node.js?

Hit GET /api/verifyServerHash with the original clientSeed and the saved serverHash. The endpoint returns true if the hash matches our records for that client seed.

How should I pick a clientSeed?

Use a value that's deterministic and meaningful to your context — a request ID, user ID, hand number, or block hash. The same clientSeed will always reproduce the same outcome for verification.

Quickstart with Node.js

Requirements

Node.js 18+ (which ships with a built-in global fetch). No extra dependencies are needed for the basic flow.

Generate an outcome

const BASE = "https://api.provable.io";
const clientSeed = "my-app-user-42";

const res = await fetch(
    `${BASE}/api/ints?clientSeed=${encodeURIComponent(clientSeed)}&count=5&min=1&max=100`
);
const data = await res.json();
console.log("outcome:", data.outcome);
console.log("serverHash:", data.serverHash);

Verify it later

const verify = await fetch(
    `${BASE}/api/verifyServerHash?clientSeed=${encodeURIComponent(clientSeed)}&serverHash=${data.serverHash}`
);
const ok = await verify.json();
console.log(ok ? "✅ verified" : "❌ mismatch");

Tips

Use a stable clientSeed per user or per session — that's what ties subsequent verifications back to the original outcome.
Persist the serverHash alongside whatever you do with the result so you can audit it later.
For richer flows (e.g. running the verification math locally), install the open-source core: npm install @provableio/provable-core.

Requirements

Generate an outcome

Verify it later

Tips

Next steps