How signing works

There are no API keys. Your wallet is your identity, in two ways:

Signed terms. Launching a coin, registering a strategy: you sign a short text message that pins the exact terms. These calls come as a prepare / submit pair.
Signed transactions. Sending a launch, routing fees: the transaction itself is what you sign, in your wallet, and that is the authorisation. No message.

The pair works like this:

Prepare

POST …/prepare with the terms. It returns the exact text to sign as message, and ts, the timestamp embedded in it. Nothing is stored or spent.

Sign

Sign message in your wallet. The message embeds a hash of the terms, so nothing can change between the two calls.

Submit

POST …/submit with the same terms, plus ts and signature. Signatures are valid for five minutes.

Solana

Sign the message’s UTF-8 bytes with ed25519, exactly as a wallet’s signMessage does. No prefix, no hashing. Send the signature as base58.

import nacl from "tweetnacl";
import bs58 from "bs58";

const { data } = await fetch("https://purps.lol/api/v1/launches/prepare", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify(terms),
}).then((r) => r.json());

const bytes = new TextEncoder().encode(data.message);
const signature = bs58.encode(nacl.sign.detached(bytes, keypair.secretKey));

await fetch("https://purps.lol/api/v1/launches/submit", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({ ...terms, image, ts: data.ts, signature }),
});

With a browser wallet, const sig = await wallet.signMessage(bytes) gives the same bytes to base58-encode.

Robinhood Chain

Sign with personal_sign (EIP-191). With viem:

const signature = await walletClient.signMessage({ message: data.message });

Send the 0x-hex signature as returned. The wallet address in the message is lower-cased; send creatorWallet in any case and we lower-case it the same way.

Transactions

We never sign a transaction. On Solana, submit returns unsigned transactions as base64; you sign them and send them through POST /transactions/send, which only forwards to the launchpad programs. On Robinhood Chain, submit returns EVM transactions as { to, data, value, chainId } steps that you send from your own wallet. When a flow gives you more than one transaction, send them in order and wait for each to confirm before sending the next: a later one spends what an earlier one produced. /transactions/send waits up to 8 seconds and tells you confirmed; if false, poll GET /transactions/{signature} every couple of seconds until it is. A launch’s create transaction also needs the mint keypair’s signature. Submit returns it as mintSecret; it has no power beyond that one transaction.

import { Keypair, VersionedTransaction } from "@solana/web3.js";

const tx = VersionedTransaction.deserialize(Buffer.from(build.transactions[build.createIndex], "base64"));
tx.sign([creatorKeypair, Keypair.fromSecretKey(bs58.decode(build.mintSecret))]);
const signed = Buffer.from(tx.serialize()).toString("base64");

Start here

Launch

After launch

Solana

Robinhood Chain

Transactions

​Solana

​Robinhood Chain

​Transactions

Solana

Robinhood Chain

Transactions