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Create a stream in the dashboard, then open its URL over SSE. Streams is an allowlisted beta: open Streams in the dashboard and choose Request access. You also need an enabled account RPC API key (keys) and enough balance for delivery.

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1. Create a stream

Sign in at lasso.sh and open Streams. Choose a chain, enter your contract addresses, select events, and choose a starting block. Leave From block blank to start at the latest block, or enter 0 for genesis. Save the stream, then copy its read URL with your account RPC key. Store the URL privately. This example selects all logs at one contract on Base:
The examples append parameters with &. For a URL without filters, such as .../base/blocks, add the first one with ? instead. If you use the copied dashboard URL, keep its filters. The examples below set from themselves; remove an existing from query parameter before appending it.

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2. Open an SSE connection

One connection pushes pages as blocks arrive. Each complete frame looks like:
items holds matching logs, ordered by block number then log index. A quiet filter can produce an empty page. Stop curl with Ctrl-C. To backfill, replace from=latest with your starting block number. Curl displays pages but does not persist them. In an app, apply each page and save next in one transaction. After a disconnect, resume from that saved value:
Last-Event-ID wins over from. Set SAVED_NEXT to your last committed cursor, not merely the last frame received.

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3. Try polling

For cron, serverless or batch jobs, omit the SSE header. Each request returns one JSON page and waits up to 20 seconds at the tip:
Use wait=0 to drain available pages in a scheduled job; stop when next stays unchanged. A 503 response means retry the same position after Retry-After.

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Positions

from is required. Use a decimal block number, latest, or the opaque next from a page. Never reuse a cursor with a changed chain, source or filter.

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