# Collection tokens · Elysium API · Femtos

> Tokens of a collection by id, with their owner and metadata URI.

- 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/nft-tokens

## Collection tokens — GET `/v1/nfts/tokens`

Tokens of a collection by id, with their owner and metadata URI.

| Param | In | Example or values |
|---|---|---|
| `layer` | query | `elysium` |
| `collection` | query | `<collection>` |
| `limit` | query | `20` |

```bash
curl -H "Authorization: Bearer $FEMTOS_KEY" "https://api.femtos.xyz/v1/nfts/tokens?layer=elysium&collection=<collection>&limit=20"
```

| Field | Type | Meaning |
|---|---|---|
| `tokens[]` | object | {tokenId, standard, owner, uri, firstSeenBlock, lastTransferBlock} |
| `owner` | string \| null | ERC-721 owner, 0x0 once burnt; null for ERC-1155 |
| `uri · uriLength` | string \| null · int | URI as returned; over 2,048 characters: null + its length |
| `next · after` | string · query | last token id, pass as after for the next page |

## Related (NFTs)

- [Active NFT collections](https://femtos.xyz/elysium/nft-collections.md): Collections with the most transfers over the last 1 h or 24 h.
- [NFT collection](https://femtos.xyz/elysium/nft-collection.md): Metadata, tokens seen and 24 h activity of one collection.
- [NFTs of a wallet](https://femtos.xyz/elysium/nft-owned.md): ERC-721 tokens owned and ERC-1155 balances of one address.
- [NFT transfers](https://femtos.xyz/elysium/nft-transfers.md): Transfers of a collection or one token, newest first.

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