# Forming candle · Elysium API · Femtos

> The forming candle, pushed once per block where it changes.

- 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-candles

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

## Forming candle — WS `elysium.candles`

The forming candle, pushed once per block where it changes.

| Param | In | Example or values |
|---|---|---|
| `pair` | filter | `<pair>` |
| `tf` | filter | `1s`, `15s`, `1m`, `5m`, `15m`, `1h`, `4h`, `1d` |

```json
{"op":"subscribe","channel":"elysium.candles","filter":{"pair":"<pair>","tf":"1m"}}
```

| Field | Type | Meaning |
|---|---|---|
| `snapshot: true` | Candle[] | last 300 candles at subscribe |
| `data` | Candle | the forming candle, same shape as REST |

## Related (Market data)

- [Candles](https://femtos.xyz/elysium/candles.md): OHLCV of one pool in pair price, USD and market cap, ascending, UTC-aligned.
- [Trades](https://femtos.xyz/elysium/trades.md): Latest swaps of one pool, newest first.
- [Trades stream](https://femtos.xyz/elysium/ws-trades.md): The swaps of one pool, one message per block that has some.
- [Daily token volume](https://femtos.xyz/elysium/volume.md): USD swap volume of a token per UTC day, both sides of every priced swap. Testnet pool prices.
- [Token transfers](https://femtos.xyz/elysium/transfers.md): ERC-20 Transfer events of one token, newest first.
- [Liquidity events](https://femtos.xyz/elysium/liquidity.md): Liquidity added to and removed from one pool, newest first.

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