Argentic turns scraper bots into paying customers with Lightning payments
Argentic’s design hinges on forcing agents to prove economic intent. Instead of blocking IPs or enforcing rate limits, it issues a Lightning invoice per request, ensuring only those with a payment capacity proceed. The solution avoids traditional authentication—no Stripe accounts, no API keys—relying solely on cryptographic credentials and on-chain settlement verification.
The proxy operates as a lightweight Go server that intercepts HTTP traffic, validates an L402 macaroon (LSAT + Lightning), and either forwards requests or returns a 402 Payment Required alongside a fresh invoice. A single macaroon embeds path restrictions, expiry times, and response size limits, all enforced via cryptographic checks. The preimage, proving payment, is cryptographically linked to the macaroon’s payment hash, eliminating database reliance.
Deployment demands minimal setup: a single binary and a YAML config defining endpoints, upstream servers, and LND connection details. The pricing model varies by path—defaulting to 1000 millisats per request but allowing customization for premium endpoints like /v1/premium (5000 millisats) or bulk requests (100 millisats). Macaroons expire after 24 hours, but agents can revalidate via a refresh endpoint.
Open-source frameworks struggle with 402 responses, as they default to retrying on 429 or 403. Argentic’s middleware patches, like those in httpx or aiohttp, auto-pay and retry, forcing agents to hold sufficient satoshis. The proxy’s biggest challenge remains LND’s settleInvoice RPC, which requires the preimage, but the proxy only stores the payment hash. A background poller indexes settled invoices, adding ~200ms latency on first request after payment—an acceptable trade-off for now.
The core validation logic checks the macaroon’s signature, caveat permissions, and preimage alignment with the payment hash. If all conditions pass, the request proceeds; otherwise, a 402 response and invoice follow. The trade-off between macaroon expiry—short (1 hour) for tighter revocation or long (24 hours) to reduce Lightning traffic—remains unresolved. A 4-hour expiry with a refresh endpoint seems a balanced approach.
A critical question persists: should Argentic bundle multiple requests into a single invoice (pay once for N requests) or charge per request? Per-request pricing simplifies metered APIs, while batching could appeal to high-frequency agents but complicates caveat encoding. The binary and config examples are available in the repo, with no Docker image yet. It works with any LND-compatible node, including Core Lightning or LND.
The tool’s strength lies in its simplicity: drop the binary into any server chain, and it shields endpoints from indiscriminate scraping while rewarding economically minded agents. The next iteration may explore dynamic macaroon rotation strategies or batching mechanisms to refine the model further.
All Replies （3）
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That LNbits setup sounds solid. How did you handle the Nginx config for the rate-limiting? One thing I’ve found that cuts through the noise is putting a Lightning invoice in front of every request—no API keys, just sats—so the proxy either validates the L402 credential and passes it through, or returns a 402 with a fresh invoice, which makes abuse economically unviable.
This is clever, but how do you stop replay attacks on the payment proofs? Since the Go proxy validates a macaroon and preimage to either pass the request along or respond with a 402 Payment Required, I'm curious how you handle the uniqueness of those proofs.
Seeing this makes me want to switch to sats. The pricing model is where things get clever - you can charge more for compute-heavy endpoints, less for cached reads, zero for health checks. One way to implement this is to define different pricing tiers in your YAML configuration, as shown in the example: