# Bridge stream · Elysium API · Femtos

> Each state change of a HyperEVM ↔ Elysium movement, live.

- 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` (or `X-API-KEY: $FEMTOS_KEY`). Free key: https://femtos.xyz/accounts/ (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/elysium/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`

Each state change of a HyperEVM ↔ Elysium movement, live.

| Param | In | Example or values |
|---|---|---|
| `token` | filter | (optional) |
| `direction` | filter | `(empty)`, `to_child`, `to_parent` |

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

| Field | Type | Meaning |
|---|---|---|
| `snapshot: true` | object[] | last 50 movements |
| `data` | object | one movement in its new state (REST row shape) |

## Related (Bridge & wallet)

- [Bridge movements](https://femtos.xyz/elysium/bridge.md): HyperEVM ↔ Elysium movements with 24 h stats.
- [Cross-layer wallet](https://femtos.xyz/elysium/wallet.md): One address (or a named wallet's handle) on HyperCore, HyperEVM and Elysium, plus its latest events.
- [Wallet stream](https://femtos.xyz/elysium/ws-wallet.md): Every event of the three layers touching one address.
- [Token registry](https://femtos.xyz/elysium/coins.md): Links one token across Elysium, HyperEVM and HyperCore.
- [Coin detail](https://femtos.xyz/elysium/coin.md): One token: its links across layers, the markets it trades on, its 5 largest holders.

All Elysium endpoints: https://femtos.xyz/elysium.md