# Freshness · Elysium API · Femtos

> Head and lag of each layer, measured now.

- 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/hypercore/status

## Freshness — GET `/v1/status`

Head and lag of each layer, measured now.

```bash
curl -H "Authorization: Bearer $FEMTOS_KEY" "https://api.femtos.xyz/v1/status"
```

| Field | Type | Meaning |
|---|---|---|
| `layers.hypercore` | object | {state, head, headTime, lagMs} |
| `layers.hyperevm` | object | {state: syncing \| live, head?, headTime?, lagMs?, chainHead?, blocksBehind?, behindMs?, clock?, reason?} |
| `layers.elysium` | object | {state, network, head, headTime, lagMs, chainHead?, blocksBehind?, behindMs?, clock?} |
| `chainHead · blocksBehind · behindMs` | int · int · ms | EVM layers: the node’s own head (pushed), how far our indexed head is behind it; behindMs = how long the next block has waited, on our receive clock (0 = in sync) |
| `stream · flows` | object | our two live feeds: {connected, lagMs} |
| `bridges` | object | HyperCore ↔ HyperEVM matching: {evm_to_core, core_to_evm: {legs, matched, coverage, p50Ms, p99Ms}} |
| `serverTime` | int | server clock (ms) |

## Related (Reference)

- [Blocks stream](https://femtos.xyz/elysium/ws-blocks.md): Each new Elysium block header, from our node.
- [Check your key](https://femtos.xyz/elysium/whoami.md): Answers the name your key is registered under, its tier, billing state and the limits in force.
- [OpenAPI document](https://femtos.xyz/elysium/openapi.md): The OpenAPI 3.1 contract of every REST call, public.

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