Polling Solana for USDC on a public RPC: what the rate limits mean
GetAgentCap team · published 10/4/2026
Public RPC endpoints are free and keyless, which makes them a reasonable place to start. They are also shared, rate-limited and offered without a service guarantee, and that shapes how you can poll for agent payments.
What a public endpoint is
The public Solana mainnet endpoint is operated for general use and applies limits per client IP address. The exact numbers are documented by the operator and can change, so check the current figures rather than relying on a blog post, including this one.
Because the limit is per IP, serverless platforms matter: many invocations can share egress addresses, so your effective budget may be smaller than a single script's.
Design for being told no
Expect HTTP 429 responses and treat them as normal. Back off with a delay that grows on repeated failures, add random jitter so parallel jobs don't retry in lockstep, and cap total retries so a bad window can't run forever.
A poller that fails closed on rate limiting and picks up where it left off on the next run loses nothing, provided it stores its position and doesn't skip ahead.
Ask for less
Query by the specific address you care about instead of scanning broad ranges, and request only the signatures and transactions you haven't recorded yet.
Remember that USDC on Solana lives in token accounts, so the addresses worth watching are the token accounts associated with a wallet, not only the wallet's own address.
When to move to a keyed provider
Switch when you see sustained throttling, when you need guaranteed freshness, or when you track many wallets. A paid or keyed provider gives you higher limits and a support path, in exchange for a secret to manage.
Until then, a careful poller on a public endpoint is a fine starting point, and it carries no credentials that could leak.