# Bridge stream · API reference · Femtos

> Each HyperCore ↔ HyperEVM transfer, initiated then completed. WebSocket channels elysium.bridge · bridge.transfers on Elysium, HyperCore and HyperEVM: parameters, response fields and a live call per layer.

- Base URL: `https://api.femtos.xyz/v1` (REST) · `wss://api.femtos.xyz/v1/ws` (WebSocket) · MCP: `https://api.femtos.xyz/mcp`
- Auth: `Authorization: Bearer $FEMTOS_KEY`. Free key: https://femtos.xyz/account/new (browser), or with
  no browser: `GET https://femtos.xyz/accounts/agent/challenge`, solve its proof of work, then `POST https://femtos.xyz/accounts/agent/signup`
  (https://femtos.xyz/agents.md#agent-onboarding)
- Decimals are exact strings, times Unix milliseconds, addresses lowercase `0x`
- Whole API in one file: https://femtos.xyz/agents.md · OpenAPI: https://api.femtos.xyz/v1/openapi.json · Index: https://femtos.xyz/llms.txt
- Page with live calls: https://femtos.xyz/reference/ws/bridge

WebSocket: get a ticket (`POST https://api.femtos.xyz/v1/ws-ticket` with your key), connect to `wss://api.femtos.xyz/v1/ws?ticket=$TICKET`, send the frame below; the first message has `"snapshot": true`. Details: https://femtos.xyz/agents.md#websocket

## Bridge stream — WS `elysium.bridge · bridge.transfers`

- Elysium: Each state change of a HyperEVM ↔ Elysium movement, live.
- HyperCore, HyperEVM: Each HyperCore ↔ HyperEVM transfer, initiated then completed.

Layers: Elysium, HyperCore, HyperEVM.
Page with live calls: https://femtos.xyz/reference/ws/bridge?layer=<elysium|hypercore|hyperevm>

| Param | In | Example or values | Meaning |
|---|---|---|---|
| `token` | filter | (optional) | Token: its HyperEVM address, or hype |
| `direction` | filter | `(empty)`, `to_child`, `to_parent` (Elysium); `(empty)`, `evm_to_core`, `core_to_evm` (HyperCore, HyperEVM) | to_child \| to_parent |
| `account` | filter | (optional) | Account of the bridge leg: 0x address or a named wallet's handle (HyperCore, HyperEVM) |
| `min_amount` | filter | (optional) | Minimum amount, token units (HyperCore, HyperEVM) |

Elysium:

```json
{"op":"subscribe","channel":"elysium.bridge","filter":{}}
```

HyperCore, HyperEVM:

```json
{"op":"subscribe","channel":"bridge.transfers","filter":{}}
```

| Field | Type | Meaning |
|---|---|---|
| `snapshot: true` | OrbitTransfer[] | last 50 movements (Elysium) |
| `data` | OrbitTransfer | one HyperEVM <-> Elysium movement in its new state (the evm_elysium row of GET /api/bridges): {status, detail, direction, chain, value, token, bridge_latency_ms} (Elysium) |
| `snapshot: true` | CoreEvmTransfer[] | last 50 transfers (HyperCore, HyperEVM) |
| `data` | CoreEvmTransfer | one HyperCore <-> HyperEVM transfer per state change, initiated then completed (the core_evm row of GET /api/bridges): {status, direction, token, account, system_address, amount, core, evm, matched_by, bridge_latency_ms, depositor, beneficiary, …} (HyperCore, HyperEVM) |

## Related (Bridges & wallets)

- [Cross-layer wallet](https://femtos.xyz/reference/wallet.md) `GET /v1/wallet/{address}`: One address (or a named wallet's handle) on HyperCore, HyperEVM and Elysium, plus its latest events. (Elysium, HyperCore, HyperEVM)
- [Wallet stream](https://femtos.xyz/reference/ws/wallet.md) `WS wallet`: Every event of the three layers touching one address. (Elysium, HyperCore, HyperEVM)
- [Swaps by wallet](https://femtos.xyz/reference/wallet-trades.md) `GET /v1/trades`: Every swap a wallet sent (or a pool’s, a token’s), newest first, filterable by token, side, size and time. (Elysium, HyperEVM)
- [Transfers by wallet](https://femtos.xyz/reference/wallet-transfers.md) `GET /v1/transfers`: ERC-20 transfers sent and received by a wallet, newest first, filterable by token, direction, size and time. (Elysium, HyperEVM)
- [Ledger stream](https://femtos.xyz/reference/ws/ledger.md) `WS hc.ledger`: Deposits, withdrawals, transfers and other non-trade balance moves. (HyperCore)
- [Bridge movements](https://femtos.xyz/reference/bridge.md) `GET /v1/bridges`: Matched HyperCore ↔ HyperEVM transfers with 24 h stats. (Elysium, HyperCore, HyperEVM)
- [Bridge coverage](https://femtos.xyz/reference/bridge-coverage.md) `GET /v1/bridges/coverage`: Every HyperCore ↔ HyperEVM leg since our data starts, paired with its other leg: matched share per direction and token, why the others are not, latency. (HyperCore, HyperEVM)

Every page: https://femtos.xyz/reference.md