Backend APIs

Cashmere runs two public HTTPS APIs. Neither needs an API key.

Host	Use it to
`https://gas.cashmere.exchange`	Get the signed fee quote that every Cashmere transfer needs, plus live fees and token prices
`https://kapi.cashmere.exchange`	Track transfers, read protocol stats and query points and leaderboards

The API Reference lists every parameter and field. This page covers what an integration needs to get right.

Gas API (`gas.cashmere.exchange`)

Purpose

The Gas API prices each route and signs a fee quote that the Cashmere contracts verify on-chain. A quote is valid for about 100 seconds.

REST Endpoints

Endpoint	Description
`GET /getEcdsaSig_native`	Signed quote for EVM source chains (`transfer`, `transferV2` and their permit variants)
`GET /getEd25519Sig_native`	Signed quote for Solana, Aptos and Sui source chains
`GET /tokenPrices`	USD price of each chain’s gas token, keyed by chain name
`GET /health`	Readiness probe: `{ "status": "healthy", "timestamp": "…" }`

`GET /getEcdsaSig_native`

Query	Type	Notes
`localDomain`	number	Source chain’s CCTP domain, for example `0` for Ethereum
`destinationDomain`	number	Destination domain
`isV2`	boolean	`true` for `transferV2`. `false` signs the V1 `transfer`, which Circle stops accepting on 1 December 2026
`isNative`	boolean	Required. `true` to pay the fee in the source chain’s gas token, `false` to take it from the USDC

GET https://gas.cashmere.exchange/getEcdsaSig_native?localDomain=0&destinationDomain=3&isV2=true&isNative=false

{
  "fee": "190000",
  "deadline": "1793034101",
  "signature": "0x8ab3…1b",
  "isNative": false,
  "cctpVersion": 2
}

fee is in USDC base units (6 decimals) with isNative=false, and in wei with isNative=true. It pays for the mint on the destination chain, so it depends mostly on where the USDC goes: in October 2026, 0.19 USDC into most chains, 0.79 into Solana and about 1.48 into Ethereum. Request a quote for every transfer instead of hardcoding a fee.
deadline is in unix seconds, about 100 seconds after the quote was issued. The contract reverts after it.
signature is a 65-byte ECDSA signature. Pass fee, deadline and signature to the contract unchanged, and with isNative=true send fee as the transaction’s value.

Signature payload The contract recomputes this digest and checks the signature against it with ecrecover, without the \x19Ethereum Signed Message prefix:

keccak256(abi.encodePacked(
    uint32(localDomain),
    uint32(destinationDomain),
    uint128(fee),
    uint64(deadline),
    bool(isNative),
    uint8(cctpVersion)   // 1 for transfer and transferWithPermit, 2 for the V2 variants
));

`GET /getEd25519Sig_native`

Query	Type	Notes
`localDomain`	number	`5` Solana, `8` Sui, `9` Aptos
`destinationDomain`	number	Destination domain
`isNative`	boolean	Required. `true` to pay in SOL, SUI or APT, `false` to take the fee from the USDC
`version`	number	`2` for the V2 entry points, `1` for Solana V1. Without it the message has no version byte, which only the V1 Aptos and Sui calls accept

GET https://gas.cashmere.exchange/getEd25519Sig_native?localDomain=5&destinationDomain=0&isNative=false&version=2

{
  "signature": "0x6b8f…0c",
  "message": "0x020500000000000000ab981600000000007587df6a0000000000",
  "publicKey": "0x93ab…af",
  "destinationDomain": "0",
  "fee": "1480875",
  "deadline": "1793034101",
  "isNative": false,
  "version": 2
}

fee is in USDC base units with isNative=false. With isNative=true it is in lamports on Solana (9 decimals), octas on Aptos (8) or MIST on Sui (9). Message encoding message holds exactly the bytes that were signed, little-endian: 26 bytes, or 25 without version.

Bytes	Field	Type
0	`version`	`u8` (only present when you pass `version`)
1–4	`localDomain`	`u32`
5–8	`destinationDomain`	`u32`
9–16	`fee`	`u64`
17–24	`deadline`	`u64`
25	`isNative`	`bool`

This is the Borsh layout the Solana program verifies, and the BCS layout of TransferParamsV2 on Aptos and Sui. On Solana, put publicKey, message and signature in an Ed25519Program instruction right before the transfer instruction. Aptos and Sui take the signature as a call argument. See Signed Payloads.

WebSocket Broadcast

wss://gas.cashmere.exchange/subscribe sends the current fees and token prices as soon as you connect. Use it to show live fees in a UI, but request a signed quote right before each transfer: only a quote carries a signature.

{ "type": "fees", "data": { "ethereum": { "fee": { "arbitrum": { "native": "82063508517328", "usd": "190000" } }, "gas": { "native": "…", "usd": "…" } } } }
{ "type": "tokenPrices", "data": { "ethereum": "2315.28", "solana": "100.99" } }

Keys are chain names (ethereum, arbitrum, solana…), not domain IDs.
fee.<destination>.native is in the source chain’s smallest native unit, and usd is in USDC base units ("190000" is 0.19 USDC).
Token prices are USD amounts as decimal strings, the same as GET /tokenPrices.

Operational Notes

Request a quote right before the user signs, and a fresh one if more than about 70 seconds have passed: the contracts revert once block.timestamp passes deadline.
Booleans must be lowercase true or false.
A missing isNative, an unknown domain or any other bad input returns HTTP 500 with {"error":"Internal Server Error"}, not 400. Check your parameters before retrying.
A 5xx on a valid request means the API can’t price the route right now: retry with backoff, and never sign with an expired quote.
For live fees, use the WebSocket instead of polling the quote endpoints.

Transaction APIs (`kapi.cashmere.exchange`)

`/transactionsmainnet`

Every mainnet transfer made through Cashmere, newest first.

Query	Description
`senders`	Comma-separated sender addresses
`addr_or_tx_hash`	An ENS (`.eth`) or SNS (`.sol`) name, an address or a transaction hash. An unknown name returns `400 {"error":"invalid ens"}`. Lookups by address or hash can take over a minute: filter by `senders` instead
`source_domain` / `destination_domain`	Filter by CCTP domain
`start_time` / `end_time`	Unix-second bounds on `created_at`
`limit`	Page size, default 10
`cursor`	The previous page’s `next_cursor` (`<unix_ts>_<id>`)

GET https://kapi.cashmere.exchange/transactionsmainnet?senders=0xYourAddress&limit=20

{
  "transactions": [
    {
      "id": 882672,
      "source_tx_hash": "0xSourceTxHash…",
      "block": 158712232,
      "source_domain": 2,
      "destination_domain": 3,
      "sender": "0xSenderAddress…",
      "recipient": "0xrecipientaddress…",
      "solana_owner": "0x0000000000000000000000000000000000000000",
      "deposit_amount": 10000000,
      "receive_amount": 9998700,
      "max_fee": 1300,
      "relayer_fee": 190000,
      "is_gas_drop_in_native": false,
      "gas_drop_amount": 0,
      "gas_drop_status": "pending",
      "gas_drop_tx_hash": null,
      "message_hash": "0x0000…",
      "attestation_hash": "0x…",
      "nonce": "0x…",
      "domain_nonce": 82732,
      "version": 2,
      "confirmed": true,
      "destination_tx_hash": "0xDestinationTxHash…",
      "destination_tx_status": "success",
      "source_tx_error": null,
      "attestation_error": null,
      "destination_tx_error": null,
      "has_source_tx_error": false,
      "has_attestation_error": false,
      "has_destination_tx_error": false,
      "created_at": "2026-10-26T14:04:43.31283Z",
      "updated_at": "2026-10-26T14:06:43.422173Z"
    }
  ],
  "next_cursor": "1793021083_882672",
  "has_more": true
}

Field	Meaning
`deposit_amount`	USDC burned on the source chain, in base units (6 decimals)
`receive_amount`	USDC minted to the recipient, after Circle’s fee (at most `max_fee`)
`relayer_fee`	Cashmere’s fee: USDC base units when `is_gas_drop_in_native` is `false`, otherwise the source chain’s smallest native unit
`is_gas_drop_in_native`	The transfer’s `isNative` flag: `true` when the fee was paid in the gas token
`recipient`, `solana_owner`	The CCTP recipient. Into Solana it is the USDC token account, and `solana_owner` is the wallet; otherwise `solana_owner` is zero
`confirmed`	The source transaction is confirmed
`destination_tx_status`	`success` once the USDC is minted, `failed` if the mint transaction failed (see `destination_tx_error`)
`gas_drop_*`	Gas drop is not offered: always 0 and `pending`

Native fees in wei can exceed Number.MAX_SAFE_INTEGER, and JSON.parse then rounds them. Use them for display, or parse the body with a big-integer JSON parser.
destination_tx_hash can be all zeros even when the status is success.
Responses are cached for 5 seconds, so polling more often than that returns the same page.

`/transactions`

The same query parameters and schema, for testnet transfers. It has no data newer than October 2025.

Points & Leaderboard API (`kapi.cashmere.exchange`)

Public endpoints for Cashmere’s points program and protocol stats. Stats responses are cached for 60 seconds, and leaderboard responses for 5. The Analytics reference shows every payload.

Endpoint	Returns
`GET /users/leaderboard`	Points leaderboard: `network` defaults to `devnet`, so pass `network=mainnet`. `limit` defaults to 50 and goes up to 100 (larger values fall back to 50), plus `offset` and `search`
`GET /users?domains=<name>.csm`	One profile’s points, rank and bound wallets per chain
`GET /users?wallets=<address>_evm,<address>_solana`	Points for each wallet
`GET /users/messages`, `POST /users/verify`	Wallet binding for the Cashmere app (see Wallet Binding)
`GET /stats/mainnet/volumes`	Lifetime volume `total_volume` in USDC base units, or `user_volume` with `?senders=`
`GET /stats/mainnet/volumes/hourly`, `/daily`	Volume buckets in USD: last 24 hours or last 30 days by default
`GET /stats/mainnet/fees`	Fee buckets in USD, with `period=hourly` (default), `daily`, `weekly` or `monthly` and `limit` up to 1000
`GET /stats/mainnet/transactions`	`total_transactions`
`GET /stats/mainnet/chain-shares`	Volume per CCTP domain: `domain`, `amount`, `total_amount`
`GET /stats/mainnet/wallets`, `/stats/wallets`	`unique_senders_count` on mainnet or testnet

Points and multipliers are floats; round them for display. An unknown profile returns 404 {"error":"user not found"}.

Smart Contract Integration (Quick Ref)

Request a quote. On EVM, call /getEcdsaSig_native with isV2=true; on Solana, Aptos and Sui, call /getEd25519Sig_native with version=2. Always pass isNative.
Fill the contract parameters:
- fee, deadline and signature from the quote, unchanged;
- maxFee from Circle’s minimumFee at https://iris-api.circle.com/v2/burn/USDC/fees/{source}/{destination} (see From Quote to Call);
- gasDropAmount 0, since gas drop is not offered;
- on EVM, hookData 0x00: Circle rejects empty hook data.
Approve amount USDC (EVM). With isNative=true, send fee as the transaction’s value on EVM, and on Sui pass it as a coin split from gas; the Solana and Aptos contracts take it from the sender’s balance.
Submit before deadline.
Poll /transactionsmainnet until destination_tx_status is success.

Don’t cache or reuse quotes. Each one is signed for a single route, fee mode and CCTP version, and expires about 100 seconds after it is issued.

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Developer Resources

API Reference

Gas API (`gas.cashmere.exchange`)

Purpose

REST Endpoints

`GET /getEcdsaSig_native`

`GET /getEd25519Sig_native`

WebSocket Broadcast

Operational Notes

Transaction APIs (`kapi.cashmere.exchange`)

`/transactionsmainnet`

`/transactions`

Points & Leaderboard API (`kapi.cashmere.exchange`)

Smart Contract Integration (Quick Ref)

​Gas API (gas.cashmere.exchange)

​Purpose

​REST Endpoints

​GET /getEcdsaSig_native

​GET /getEd25519Sig_native

​WebSocket Broadcast

​Operational Notes

​Transaction APIs (kapi.cashmere.exchange)

​/transactionsmainnet

​/transactions

​Points & Leaderboard API (kapi.cashmere.exchange)

​Smart Contract Integration (Quick Ref)

Gas API (`gas.cashmere.exchange`)

Purpose

REST Endpoints

`GET /getEcdsaSig_native`

`GET /getEd25519Sig_native`

WebSocket Broadcast

Operational Notes

Transaction APIs (`kapi.cashmere.exchange`)

`/transactionsmainnet`

`/transactions`

Points & Leaderboard API (`kapi.cashmere.exchange`)

Smart Contract Integration (Quick Ref)