LayerZero Value Transfer API

Unified REST API for moving assets across 170 blockchains. One endpoint consolidates multiple bridge/swap protocols — you get a quote, sign the returned transactions, and poll for completion. Gas is paid on the source chain only.

Base URL: https://transfer.layerzero-api.com/v1

Auth (Starchild): the key is injected by sc-proxy — you do NOT set LAYERZEROAPIKEY. transfer.layerzero-api.com is a proxied domain, so route transfer calls through core.http_client and the platform adds the real key. The x-api-key header value can be anything (or omitted); the proxy overrides it.

from core.http_client import proxied_post, proxied_get
r = proxied_post(
    "https://transfer.layerzero-api.com/v1/quotes",
    json=body,
    headers={"x-api-key": "proxy", "SC-CALLER-ID": f"chat:{thread_id}"},
    timeout=40,
)

Discovery endpoints (/chains, /tokens, /metadata) need no auth and work with plain curl too. A direct curl to a transfer endpoint bypasses the proxy and returns {"error": "Unauthorized"} — use proxied_* for anything that needs the key.

Route types

The API picks the optimal route; you don't normally need to choose.

Workflow

1. GET  /chains, /tokens        → discover routes (optional)
2. POST /quotes                 → get quote.id, feeUsd, userSteps
3. Execute userSteps            → sign & send each tx (or EIP-712 signature)
4. GET  /status/{quoteId}       → poll every ~4s until terminal

1. Discovery

curl -s https://transfer.layerzero-api.com/v1/chains
# → { "chains": [{ "name": "Base", "chainKey": "base", "chainType": "EVM",
#                 "chainId": 8453, "nativeCurrency": { "symbol": "ETH", "decimals": 18,
#                 "address": "0xEeee...EEeE" } }, ...] }
# Note: results are under the "chains" key (not a bare array). chainType is
# uppercase: EVM, SOLANA, APTOS, SUI, TON, TRON, STARKNET, IOTAMOVE.

# Tokens receivable from a given source token:
curl -s "https://transfer.layerzero-api.com/v1/tokens?transferrableFromChainKey=base&transferrableFromTokenAddress=0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE"
# → { "tokens": [{ chainKey, address, decimals, symbol, name, price.usd }, ...],
#     "pagination": { "nextToken"? } }   (results under the "tokens" key)

• Native token address is 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE.
• List endpoints paginate: pass pagination[nextToken] and keep fetching until

the response has no nextToken.

• GET /metadata returns contract deployment addresses per chain.

2. Get a quote

from core.http_client import proxied_post
r = proxied_post(
    "https://transfer.layerzero-api.com/v1/quotes",
    json={
        "srcChainKey": "base",
        "dstChainKey": "optimism",
        "srcTokenAddress": "0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE",
        "dstTokenAddress": "0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE",
        "srcWalletAddress": "0xYOUR_WALLET",
        "dstWalletAddress": "0xYOUR_WALLET",
        "amount": "1000000000000000",
        "options": {
            "amountType": "EXACT_SRC_AMOUNT",
            "feeTolerance": {"type": "PERCENT", "amount": 2},
        },
    },
    headers={"x-api-key": "proxy", "SC-CALLER-ID": f"chat:{thread_id}"},
    timeout=40,
)
quote = r.json()["quotes"][0]   # id, feeUsd, dstAmount, userSteps

Response shape: {"error": null, "quotes": [{ "id", "routeSteps", "fees", "feeUsd", "feePercent", "srcAmount", "dstAmount", "dstAmountMin", "userSteps" }]}. quotes is an array (the API may return several routes); take quotes[0] unless you want to compare feeUsd.

• amount is a string in the token's local decimals (wei for ETH).
• Response: quote.id, quote.feeUsd, quote.userSteps (ordered transactions to

execute). Show the user feeUsd and expected output before executing.

3. Execute userSteps

EVM: loop through userSteps in order; each contains ready-to-send transaction calldata. Sign with the agent wallet, send, and wait for confirmation before the next step. ERC-20 transfers typically yield two steps: approve then the bridge tx.

Solana: transaction blockhashes expire in ~60s, so first regenerate fresh data:

r = proxied_post(
    "https://transfer.layerzero-api.com/v1/build-user-steps",
    json={"quoteId": "QUOTE_ID"},
    headers={"x-api-key": "proxy", "SC-CALLER-ID": f"chat:{thread_id}"},
)

Signature steps (intent routes like AORI): sign the EIP-712 payload in userStep.signature.typedData, then submit:

r = proxied_post(
    "https://transfer.layerzero-api.com/v1/submit-signature",
    json={"quoteId": "QUOTE_ID", "signatures": ["0xSIGNATURE"]},
    headers={"x-api-key": "proxy", "SC-CALLER-ID": f"chat:{thread_id}"},
)

4. Poll status

from core.http_client import proxied_get
r = proxied_get(
    "https://transfer.layerzero-api.com/v1/status/QUOTE_ID",
    params={"txHash": "0xSRC_TX_HASH"},
    headers={"x-api-key": "proxy", "SC-CALLER-ID": f"chat:{thread_id}"},
)
# → { "status": "PROCESSING", "explorerUrl": "..." }

Poll every ~4 seconds. Terminal states: SUCCEEDED, FAILED, UNKNOWN. Non-terminal: PENDING, PROCESSING. Share explorerUrl with the user.

Safety rules

• ⚠️ Never approve the LZMulticall (Wrapper) contract as a token spender. The

API-generated calldata already uses the TransferDelegate contract for approvals — execute steps as returned, don't hand-craft approvals.

• Quotes expire — get a fresh quote if execution is delayed; don't reuse old ones.
• Always confirm with the user before signing/sending real-value transactions:

state source/destination chains, token, amount, and feeUsd.

• Verify the destination address matches the user's intent before quoting.
• On FAILED or UNKNOWN, report the explorerUrl and do not retry blindly.