Fast fill

• Gasless. The user signs one EIP-712 message and a relayer sends the source transaction and pays its gas. The gas is charged in the token you send and is already taken off every quoted amount. Relay’s relayer submits Relay fast fills. Across fast fills are sponsored by BRDG: BRDG’s relayer submits the deposit to Across’s SpokePoolPeriphery, and the user’s signed USDC covers that gas plus the platform fee in the same transaction. The quote shows this as one Fast fill fee line, and BRDG refuses any amount where that fee would exceed 5%.
• Sent by the user. Mayan Swift is a solver fill too, usually about 3 seconds, but the user sends the source transaction and pays its gas. BRDG offers it only when the wallet can: see the gas check.

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How BRDG aggregates fast fills

1. POST /fastfill/quote asks only the venues with a fast lane: Relay, Across and Mayan. Every other venue is left out silently.
2. Each venue quotes its fast form only: Relay its gasless permit order where the token has one, otherwise its ordinary solver fill sent by the user (native tokens, and every Solana source); Across the sponsored deposit; Mayan its Swift route (never its slower CCTP or Wormhole routes). A venue that has no fast form for the pair answers no_route.
3. BRDG reads the sender’s native balance on the source chain once, and refuses any row the user sends (Mayan, or Relay without a permit) that the wallet cannot pay gas for.
4. The answers are ranked by what the user receives, exactly as in POST /bridge/quote. best is the winner, and rejected lists every venue that did not quote, with its reason.

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The gas check

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Supported

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Hyperliquid

• Direct. The venue credits the Hyperliquid account straight from the source chain. Relay and Mayan Swift both do, and a direct Relay row needs no gas from the user where the token has a permit.
• Through Arbitrum. The venue delivers USDC to Arbitrum and BRDG’s relayer credits the account. The row carries postStep: { kind: "hypercore_deposit", chain: "arbitrum", vm: "evm" }, and your user signs nothing after the source step - whether that step was a signature or a transaction. The relayer charges its gas plus 10 cents, capped at $1, already inside the quoted output.

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How it works

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Script

import type { Hex } from 'viem';
import { account, brdg, signEvmStep } from './evm';

const API = 'https://api.brdg.now/v1';

async function post<T>(path: string, body: unknown): Promise<T> {
  const response = await fetch(`${API}${path}`, {
    method: 'POST',
    headers: { 'content-type': 'application/json' },
    body: JSON.stringify(body),
  });
  const json = await response.json();
  if (!response.ok) throw new Error(`${json.error.code}: ${json.error.message}`);
  return json as T;
}

async function main() {
  // 1. Quote. Only fast fill venues compete; Mayan only if the wallet holds gas.
  const quote = await post<any>('/fastfill/quote', {
    fromChain: 'base',
    toChain: 'arbitrum',
    fromToken: 'USDC',
    toToken: 'USDC',
    amountAtomic: '10000000',
    sender: account.address,
  });
  if (!quote.best) throw new Error(quote.emptyReason ?? 'no fast fill route');
  console.log(`${quote.best.venue} delivers ${quote.best.amountOutAtomic} in ~${quote.best.estimatedSeconds}s`);

  // 2. Build
  const build = await post<any>('/fastfill/build', { decisionId: quote.decisionId });

  // 3. Transactions first: a one time approve to Permit2, or the Mayan order itself
  for (const step of build.steps) {
    if (step.vm !== 'evm') continue;
    const hash = await signEvmStep(step);
    await brdg.submitTransfer(build.transferId, { txHash: hash, step: step.step });
  }

  // 4. On the gasless lane, sign the message. No transaction, no gas.
  const sign = build.steps.find((step: any) => step.vm === 'sign');
  if (sign) {
    const { domain, types, primaryType, message } = sign.payload;
    const signature: Hex = await account.signTypedData({ domain, types, primaryType, message });

    // 5. Submit the signature
    const submitted = await post<any>(`/fastfill/transfers/${build.transferId}/submit`, { signature });
    console.log(submitted.status, submitted.txHash);
  }

  // 6. Wait for delivery
  const transfer = await brdg.waitForTransfer(build.transferId, {
    onUpdate: (t) => console.log(t.status),
  });
  console.log(transfer.status, transfer.receivedAmountAtomic);
}

main().catch((e) => { console.error(e); process.exit(1); });

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Errors

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Fees and referrals

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Endpoints used