> ## Documentation Index > Fetch the complete documentation index at: https://docs.lasso.sh/llms.txt > Use this file to discover all available pages before exploring further. # Streams API reference > Streams read and management endpoints, filters, page fields, authentication, limits, and error behavior. Read contract logs or block headers over SSE or JSON polling. Read endpoints use an account RPC key; saved-stream management uses an account management Bearer token. Start with the [quickstart](https://docs.lasso.sh/cloud/streams/quickstart.md) for a working request. ```bash theme={null} curl -N -sS -H 'Accept: text/event-stream' \ "https://lasso.sh/streams/k/$LASSO_KEY/base/logs?address=$CONTRACT&from=0&wait=20" ``` The full machine-readable contract is in [OpenAPI](https://lasso.sh/openapi.json). ## Read endpoints | Method | Path | Items | | - | - | - | | GET | `/streams/k/{key}/{chain}/logs` | `eth_getLogs` objects plus validated-header `blockTimestamp`, without `removed` | | GET | `/streams/k/{key}/{chain}/blocks` | Block headers without transaction, uncle or withdrawal lists | | Parameter | Location | Contract | | - | - | - | | `key` | Path | Enabled account RPC API key. Keep the URL private. | | `chain` | Path | `ethereum` / `1`, `base` / `8453`, `arbitrum` / `42161` in the beta. | | `from` | Query, required | `latest`, unsigned 64-bit decimal block number, or opaque `next` from a page. Maximum 512 characters. | | `wait` | Query | Integer seconds, 0 to 30, default 20. Use 0 to drain available pages. | | `label` | Query | 1 to 100 characters; dashboard display name only. Does not affect data, billing identity or position. | | `address` | Query, logs only | Up to 100 comma-separated addresses, matched as alternatives. | | `topic0` through `topic3` | Query, logs only | Comma-separated alternatives at each position. Positions are ANDed. Omitted filters match anything. | | `Accept` | Header | `text/event-stream` for SSE; `application/json` for polling. | | `Last-Event-ID` | Header | SSE resume position, at most 512 characters. Block number or `next`, never `latest`. Wins over `from`. | Block headers accept no address or topic filters. `latest` includes the current published tip block. `cursor=` is invalid; send `next` as `from`. ## Page response Polling returns one page with status 200, never 204. SSE returns a sequence of frames with `id: ` and `data: `, no `event` field. Empty pages are also sent. Quiet SSE waits after the first page have a one-second minimum. | Field | Type | Meaning | | - | - | - | | `from` | Integer | First block to replace in this source. | | `through` | Block mark or null | Last covered block: `{number, hash}`. | | `tip` | Integer or null | Published tip block number. | | `safe`, `finalized` | Block marks or null | Chain block tags, each `{number, hash}` when available. | | `next` | String | Opaque position for the next request. | | `items` | Array | Complete-block items ordered by block number, then log index for logs. | | `reorg` | Optional boolean | `true` on correction pages. The apply rule does not branch on it. | An unreached position returns `items: []`, `through: null` and unchanged `next`. Item quantities are JSON-RPC hex; page numbers are decimal. See [consuming pages](https://docs.lasso.sh/cloud/streams/consuming-pages.md) for the required atomic apply rule, all error codes and reconnect behavior. A temporary handoff may return 307 with no `Location`; retry the same request. ## Saved-stream management Send `Authorization: Bearer ` and JSON bodies with `Content-Type: application/json`. RPC keys cannot manage streams. Profile-scoped agents cannot manage streams; read-only agents can read but cannot mutate. All management routes require beta access (`403 not_in_beta` otherwise). | Method | Path | Body or result | | - | - | - | | GET | `/api/v1/streams` | `{streams, limits}` | | POST | `/api/v1/streams` | `{name, chain_id, source, parameters}`; returns 201 recipe | | GET | `/api/v1/streams/{id}` | Saved recipe | | PATCH | `/api/v1/streams/{id}` | `{name}`; only the name is editable | | DELETE | `/api/v1/streams/{id}` | 204; does not revoke a key or erase a consumer checkpoint | | GET | `/api/v1/streams/usage` | Account `days` and attributed `sources` | | GET | `/api/v1/streams/{id}/usage` | Account `days` and sources matching this recipe | A recipe has `id`, `name` (1 to 100 characters), integer `chain_id`, `source` (`logs` or `blocks`), `parameters`, credential-free `url_template`, `inserted_at` and `updated_at`. Substitute your key into the template locally. Recipe `parameters` accepts `address` and `topic0` through `topic3` as strings or arrays of strings; `from` as a block number or `latest`; `wait` as 0 to 30; and `label`. A recipe never stores a consumer cursor. Create a new recipe to change its source. Duplicate names are allowed. Usage endpoints accept inclusive `from_day` and `through_day` UTC dates, defaulting to seven days with a maximum range of 31 days. Totals are flushed in the background. Identical normalized filters share source attribution. Account-day minimums belong to the account: never sum the repeated `days` charges across saved recipes. ## Limits At most 100 saved recipes per account; exceeding the cap returns `409 stream_limit`. Read limits are 10 concurrent readers and two history builds per key. Page boundaries are at most 10,000 whole blocks, targeting 1 MiB of items with a 4 MiB ceiling; a larger single block is served alone or returns 503. ## Next * [Consuming pages correctly](https://docs.lasso.sh/cloud/streams/consuming-pages.md) * [Integration guides](https://docs.lasso.sh/cloud/streams/integration.md) This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.