Quickstart: Backends

Use the TypeScript SDK to subscribe, request a signed attestation for any API, publish it to a Solana feed, and build calldata for EVM and Starknet. You need a Solana devnet wallet with some Devnet SOL and Devnet USDC:

solana-keygen new                 # writes ~/.config/solana/id.json, skip if you have one
solana airdrop 1 --url devnet     # SOL for transaction fees

Get Devnet USDC from the Circle faucet (choose USDC on Solana Devnet). Step 3 prints the subscription price before paying it. The SDK is ESM-only. Put the code below in one file, quickstart.ts, in a project whose package.json has "type": "module", and run it with npx tsx quickstart.ts.

Install

npm install @molpha/sdk @anchor-lang/core bn.js

Requires Node.js 20.19 or later. @anchor-lang/core and bn.js are peer dependencies.

Initialize

import { homedir } from "node:os";
import { join } from "node:path";
import { web3 } from "@anchor-lang/core";
import { MolphaSDK, PlanType, deriveSourceIdString } from "@molpha/sdk";
import { walletFromKeypairFile } from "@molpha/sdk/utils";

const wallet = walletFromKeypairFile(join(homedir(), ".config/solana/id.json"));
const sdk = new MolphaSDK({
  connection: new web3.Connection("https://api.devnet.solana.com", "confirmed"),
  wallet,
});

Gateway rounds from the SDK are paid by a subscription. Subscribe once with the signing wallet:

if (!(await sdk.solana.readSubscription())) {
  const plan = await sdk.solana.getPlan(PlanType.Basic);
  console.log("price in USDC base units:", plan.subscriptionPrice); // 1 USDC = 1,000,000
  await sdk.solana.subscribe(PlanType.Basic, { maxPriceUsdc: plan.subscriptionPrice });
}

subscribe transfers the plan price in Devnet USDC from your wallet and cannot be undone. It fails if the wallet already has a subscription, which is why the call is guarded.

maxPriceUsdc aborts the transaction if the on-chain price is higher than you approved. Without a subscription (or delegate access), the gateway answers 403.

Define a source

const apiConfig = {
  url: "https://api.drand.sh/public/1000", // a public, fixed JSON document
  responseParser: "$.round",                // the number 1000
};
const signaturesRequired = 3;
const sourceId = deriveSourceIdString(apiConfig); // needed later to read the feed

This example source never changes, so every node reads the same value. Replace it with your own API afterwards: pick an endpoint that returns the same value to every node, or use tolerance mode for live-moving numbers. signaturesRequired must be at least 3, the network minimum.

Request a signed attestation

const result = await sdk.gateway.requestSignedData({ apiConfig, signaturesRequired, maxAge: 60 });
console.log(result.value, result.payload.timestamp, result.signature.signersBitmap);

result is an Attestation. Treat it as unverified until a verifier has checked it.

Publish it to Solana

const { signature, feed } = await sdk.solana.submitAttestation(result);
const account = await sdk.solana.readFeed(sourceId, signaturesRequired);
console.log(signature, feed, account?.value); // value is the 32 signed bytes

The program verifies the attestation before writing. The first submit creates the Feed account for (sourceId, signaturesRequired, your wallet).

Build calldata for EVM or Starknet

import { buildEvmVerifierArgs, buildStarknetVerifierArgs } from "@molpha/sdk";

const evmArgs = buildEvmVerifierArgs(result, { maxAge: 60 });       // { attestation, maxAge }
const starknetArgs = buildStarknetVerifierArgs(result, { maxAge: 60 });

Decode the verifier’s (success, code) with parseEvmVerifyResult or parseStarknetVerifyResult.

Next steps

Maintain a feed

Keep a Solana feed current, batch submits and request many sources.

SDK reference

Every client, type and helper.

Verify on EVM

Consume the attestation in Solidity.

Get started

Concepts

Access and payments

MCP server

Verify and publish

Protocol

Resources

Quickstart: Backends

Next steps

Maintain a feed

SDK reference

Verify on EVM

​Next steps

Maintain a feed

SDK reference

Verify on EVM

Next steps