Gas Sponsorship

The MemForks sponsor service covers all gas fees so developers can use MemForks on mainnet without holding any SUI.

It handles two distinct cases:

• /drip — sends a small SUI amount to a fresh address during memfork init --quick so the two MemWal bootstrap transactions (account creation and delegate key registration) can self-pay gas. This is a one-time transfer.
• /sponsor — co-signs all subsequent MemForks transactions (branch, commit, merge, etc.) so the user never needs gas again.

The user's address remains the transaction sender in both cases.

How It Works

Bootstrap drip (memfork init --quick)

Ongoing sponsorship

Service Setup

cd services/sponsor
npm install
cp .env.example .env
npm start

Required environment:

Variable	Required	Default	Description
SPONSOR_PRIVATE_KEY	Yes	—	Sponsor wallet private key.
SUI_NETWORK	Yes	mainnet	mainnet, testnet, or devnet.
SUI_RPC_URL	No	auto	Override RPC endpoint.
MEMFORK_PACKAGE_ID	No	production ID	Allowed MemForks Move package ID.
RATE_MAX_PER_WIN	No	10	Max sponsored txs per sender per window.
RATE_WINDOW_MS	No	60000	Rate limit window in ms.
RATE_IP_MAX_PER_WIN	No	40	Max txs per IP per window.
RATE_DAILY_MAX_TX	No	5000	Global daily transaction cap.
RATE_INIT_TREE_PER_IP_DAY	No	1	Max tree creations per IP per day.
SPONSOR_GAS_BUDGET	No	90000000	Gas budget per tx in MIST.
DRIP_AMOUNT_MIST	No	20000000	SUI sent per /drip (0.02 SUI).
DRIP_MIN_BALANCE_MIST	No	5000000	Skip drip if address already has this.
DRIP_IP_DAILY_MAX	No	1	Max drips per IP per 24 h.
PORT	No	3100	HTTP port.

API

Health

GET /health

Returns:

{ "ok": true, "network": "mainnet" }

Bootstrap Drip

POST /drip

Sends a small SUI amount to a fresh address so it can self-pay for the two MemWal bootstrap transactions during memfork init --quick. Called automatically by the CLI — you don't need to call this directly.

Request:

{ "address": "0x<new address>" }

Success (drip sent):

{ "digest": "<tx digest>", "amount": 20000000 }

Success (already funded, skipped):

{ "skipped": true, "message": "address already has sufficient balance", "balance": "25000000" }

Status	Meaning
429	Rate limit: 1 drip per IP per 24 h.
500	Sponsor wallet error.

Sponsor Transaction

POST /sponsor

Request:

{
  "tx": "<serialized Transaction string>",
  "sender": "0x<user address>"
}

Success:

{
  "txBytes": "<base64>",
  "sponsorSig": "<base64 signature>"
}

Common errors:

Status	Meaning
400	Invalid transaction or disallowed package call.
429	Sender exceeded rate limit.
503	Sponsor gas pool unavailable.

Configure The SDK

The CLI sets this automatically. For SDK usage in your own app:

export MEMFORK_SPONSOR_URL=https://memforks-sponsor-production.up.railway.app/sponsor

Or explicitly in code:

const client = await MemForksClient.connect({
  treeId,
  signer,
  memwal,
  sponsorUrl: "https://memforks-sponsor-production.up.railway.app/sponsor",
});

TIP

MEMFORK_SPONSOR_URL must point to the full /sponsor endpoint path. The SDK POSTs directly to the URL with no path appended.

Funding The Sponsor

Each MemForks transaction is small, but high-concurrency services should pre-split SUI into multiple gas coins to avoid contention.

sui client split-coin \
  --coin-id <COIN_ID> \
  --amounts 20000000 20000000 20000000 \
  --gas-budget 10000000

Deployment Notes

• The service is stateless.
• Deploy on Railway, Fly.io, a VPS, or any Node.js host.
• Keep SPONSOR_PRIVATE_KEY in a secret manager.
• Use an external rate limiter such as Redis if you scale horizontally.
• Restrict sponsored calls to the expected MemForks package.