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Production RPC for a viem and Next.js app on Ethereum and Base

viem’s chain configs ship with public RPC URLs. They rate limit, they come from one provider each, and they are not meant for production traffic. Before launch, give each chain an endpoint that routes across several providers and keeps answering when one of them doesn’t. Lasso gives you that as one standard JSON-RPC URL per chain. The app keeps plain viem; nothing else changes.

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1. Get a key

The response holds key, rpc_url_template, a management_token and a claim_url. There is no signup: open claim_url within 24 hours to attach the account to your login, and every URL keeps working. Store the key and token in your secret store, not in the repo. rpc_url_template contains {chain}. Replace it with ethereum and base. These URLs use balanced-fast, the Premium default for user-facing reads: it spreads traffic across providers, favoring the recently fast ones.

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2. Wire it into env config

The URL carries the key, so keep it server-side: no NEXT_PUBLIC_ prefix.
Use these clients in server components and route handlers. Browser code calls your route handlers instead of RPC directly, so the key never ships in the bundle.

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3. What it does behind the URL

  • Routes every request across several providers per chain, chosen by latency and health that Lasso measures live in each region.
  • Moves a replay-safe read to the next provider within the same request when one fails or rate limits.
  • Resends a signed transaction as the same bytes to the next provider, and returns the hash if the transaction turns out to be pending or mined.
  • Reports which provider served a request when you add ?include_meta=body.
When you want your own provider accounts or nodes in the mix, a Custom profile lists providers per chain in preference order, under the same key and a new path segment.

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4. Estimate the cost

Each method has a flat compute-unit (CU) rate at $0.000005 per CU, multiplied by the strategy: load-balanced 1×, balanced-fast 1.5×, fastest 2×. eth_call is 3 CU. A new key starts with a $0.025 balance. To fund it, subscribe to Pro from the dashboard after claiming, or add credit with POST /api/v1/accounts/<id>/credit, which any x402 or MPP client can pay. Other methods have their own rates; every method’s price per strategy is in agent.json. A paid account keeps serving on public providers for 30 days if its balance runs out, so the app doesn’t go dark on an empty balance.

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5. Check it

lasso_meta.selected_provider names the provider that answered, and upstream_latency_ms its latency.