# Gas station

> Send a little native gas to up to 10 chains from one transaction, so a wallet can transact on chains it has never used. Off by default on each deployment.

Source: https://docs.layerhop.com/guides/gas-station

Arriving on a new chain with tokens but no gas is a dead end: the wallet can't even approve a swap. The **gas station** refuels up to 10 chains with their native gas token from **one transaction** on the chain the user already has funds on. It runs at [app.layerhop.com/gas](https://app.layerhop.com/gas).

The gas station is **off unless the deployment sets `GAS_STATION_ENABLED=1`**; while it's off every `/v1/gas/*` route answers [`FORBIDDEN`](/errors/FORBIDDEN). The source is [Gas.zip](https://www.gas.zip): one deposit, split evenly across the chains you pick, usually delivered within seconds. LayerHop takes **no fee** on refuels; Gas.zip's own fee is part of the quote.

## Quote a refuel

```bash
curl -X POST https://api.layerhop.com/v1/gas/quote \
  -H "content-type: application/json" \
  -d '{"srcChain":"base","sender":"0xYourWallet","destinations":[{"chain":"arbitrum","usd":2},{"chain":"optimism","usd":2},{"chain":"bsc","usd":2}]}'
```

The quote (good for about 60 seconds) has:

- `tx`: one transaction on `srcChain`, paid in its native token (`value` = `depositWei`). Send it from `sender`.
- `destinations`: what each chain receives (`expectedWei` of its native token, its USD value, and the usual seconds).
- `fees`: `ourFeeBps: 0` and `providerFeeUsd` (the deposit minus what's delivered).
- `simulation`: an `eth_call` of `tx` from `sender`. `ok: false` usually means the wallet doesn't hold enough for the deposit plus the network fee.

Before returning `tx` we decode it and check it is a `deposit(chains, to)` call on Gas.zip's deposit contract with exactly your destinations, your recipient and the quoted value. A mismatch is a [`PROVIDER_ERROR`](/errors/PROVIDER_ERROR), never a transaction to sign. Gas.zip's own numbers are checked too: its price of the native token must be within 3% of LayerHop's price feed (the deposit is sized from it, and can't be worth more than the USD you asked for plus 3%), and each destination's Gas.zip chain id comes from a table LayerHop keeps, not from Gas.zip's live list (a chain whose id changed is not offered until we check it). Without a price of our own, or with prices apart, the quote is a `PROVIDER_ERROR`; try again shortly.

## Rules

- 1 to 10 destinations, all different, none equal to `srcChain`.
- **One amount for all**: Gas.zip splits a single deposit evenly, so every destination takes the same `usd`.
- Between **$0.50 and $50 per chain**, within Gas.zip's own limits (`GET /v1/gas/chains` lists both, per chain).
- Pay with the source chain's native token (`srcToken` may be omitted or name the native token).
- `recipient` defaults to the sender.

Destinations Gas.zip can't serve right now (e.g. out of liquidity) make the quote fail with [`NO_ROUTE`](/errors/NO_ROUTE), naming them; drop them and quote again.

## Watch it arrive

- `GET /v1/gas/status/{txHash}`: the deposit's outbound transfers per chain; `status` becomes `filled` once every one is confirmed.
- `GET /v1/gas/balances?address=…&chains=arbitrum,optimism`: native balances, for comparing before and after. The app does both every few seconds after the user signs.

Any refuel can also be looked up with the [transfer tracker](/guides/track-transfers).