> For the complete documentation index, see [llms.txt](https://parad0xlabs.gitbook.io/parad0xlabs-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://parad0xlabs.gitbook.io/parad0xlabs-docs/dna-x402-payment-rail/dna-x402.md). # What It Is ### Get paid per API call. No Stripe. No PayPal. No platform cut. *** ## The Problem With Payments Today Stripe takes 2.9% + $0.30 per transaction. PayPal freezes accounts without notice. Banks block "high risk" merchants — often arbitrarily. Credit card chargebacks can wipe out months of revenue. Every payment goes through a company that can say no, freeze funds, or shut you down. For software and AI agents (autonomous programs that do work on the internet), subscriptions are a blunt instrument. You pay $20/month whether you make 1 API call or 10,000. There is no native "pay per use" at the HTTP layer — HTTP is the protocol that powers every web request you make, the foundation of the internet. Nobody ever built money into it. Until x402. *** ## What x402 Is **Plain English:** imagine if every webpage could say "that will be $0.001 please" and your browser just paid it automatically in the background, then delivered the content. No account signup. No password. No subscription. You pay exactly for what you use, only when you use it. x402 is that standard — a payment layer built directly on top of HTTP. When a server wants payment, it returns HTTP status code 402 ("Payment Required") with a machine-readable header describing the cost and where to send it. The client pays, attaches a cryptographic receipt to the retry request, and gets the resource. **DNA x402** is the Web0 implementation of this standard, running on Solana (a fast, low-cost blockchain), paying in USDC (a dollar-pegged stablecoin — 1 USDC = $1, always). **This is not experimental.** As of April 2026, x402 has processed approximately 165 million transactions, roughly $50 million in volume, with around 69,000 active AI agents using it. Solana alone accounts for 37 million+ transactions and 70% of monthly volume. The Linux Foundation governs the standard, with Coinbase, Cloudflare, Google, Visa, Anthropic, Circle, AWS, and Vercel as named partners. *** ## Why The Receipt Matters Every x402 payment produces a cryptographic receipt. This receipt is bound to a specific `request_hash` — a fingerprint of the exact API call that was made. The receipt proves two things simultaneously: 1. Payment happened (on-chain, immutable) 2. Which specific request triggered it No third party decides whether work was delivered. The receipt IS the proof. You cannot forge it for a different request. You cannot reuse it. This is fundamentally different from every DePIN network (decentralized physical infrastructure — distributed compute/bandwidth marketplaces) that exists today: | Network | What stands between work and payment | | -------- | --------------------------------------------------------------------------------------------------------- | | Grass | A single Validator controls reward allocation | | io.net | Platform controls job assignment and pricing; a 2024 attack forged 1.8M fake GPUs | | Helium | Nova Labs/Helium Foundation oracles compute rewards in a Foundation-owned database | | Render | OTOY validates output; nodes cannot participate without proprietary OctaneRender software | | Akash | True on-chain escrow, but no work verification — you get paid whether or not delivery happened | | **x402** | **No oracle. Receipt = proof. Facilitator cosigns but never gates payment amounts or allocates rewards.** | The x402 facilitator (a lightweight cosigning service) is not a judge. It signs receipts. It does not run a work-verification database. It does not control how much you earn. That distinction is what makes DNA x402 different from every other compute payment system. *** ## Who Uses This **AI agents paying other AI agents.** An autonomous research agent needs fresh price data. It hits an x402-gated endpoint, pays $0.0003, gets the data, moves on. No human in the loop. No credit card. **Traders paying for signals per call.** Why subscribe to a signal service for $299/month when you only trade Thursdays? Pay per signal. Stop paying when you stop trading. **Developers monetizing APIs without Stripe.** No business entity required. No KYC (Know Your Customer — identity verification). No 30-day payout delays. Revenue lands in your wallet per call. **Node operators earning per inference job.** Run a local model (an AI running on your own hardware). The NULLA mesh (Web0's peer-to-peer compute layer — in development) routes jobs to you. DNA x402 handles settlement. You earn per task completed, not per hour. *** ## The Two Pieces DNA x402 ships in two halves — one for each side of a payment: **`x402-gate` — the server side** (in development). Drop it in front of any API endpoint and it starts charging. When a request arrives without payment, it returns the 402 "Payment Required" challenge; when the payment receipt comes back, it checks the receipt and lets the request through. For a developer, turning payments on is essentially a one-line change. **`x402-pay` — the client side, with a hard spending cap** (in development). It reads the challenge, pays, attaches the receipt, and retries — automatically, no human in the loop. The cap is enforced **on your own device before anything is signed**: the agent cannot spend more than you allow, ever, no matter what the server asks for. V1 settles in USDC. NULL token support comes in V2. > Want the actual code and the integration walkthrough? It's all in [**How It Works**](/parad0xlabs-docs/dna-x402-payment-rail/how-it-works.md) — this page stays jargon-light on purpose. *** ## Gaps DNA x402 Fills These are confirmed open gaps in the x402 ecosystem as of June 2026: 1. **Self-custodial Solana facilitator with non-USDC token support** — all existing Solana facilitators are USDC-only. DNA x402 V2 adds NULL. 2. **Agent wallet with hard spend caps on Solana** — existing solutions (AgentPay MCP, Harvey Budget) are EVM/Base only (Ethereum-compatible chains). No Solana equivalent exists. 3. **x402 + local LLM mesh integration** — no prior implementation connects x402 payment rails to a local compute mesh. This is the keystone of the NULLA layer. 4. **Receipt-DAG audit trail** — a DAG (Directed Acyclic Graph — like a blockchain but for linking events) that chains x402 receipt IDs to task IDs to work proofs to on-chain SPL Memo transactions. No existing x402 project builds this graph layer. 5. **Dark Passport-gated x402 endpoints** — gate access to an x402 endpoint behind a ZK proof (zero-knowledge proof — proves a fact without revealing the underlying data) of reputation. No existing project combines ZK identity verification with x402 payment. In development as part of Layer 3. *** ## Where This Fits in Web0 Web0 is a six-layer protocol stack. DNA x402 is Layer 4 (Payments). ``` Layer 1 .null domains — decentralized naming, no DNS, no ICANN [LIVE] Layer 2 Arweave content — permanent storage, censorship-resistant [LIVE] Layer 3 Dark Passport — ZK identity and reputation [LIVE primitive — reputation gate on mainnet] Layer 4 DNA x402 — pay-per-call HTTP payments [PARTIAL — access gate live on mainnet] <-- you are here Layer 5 NULLA mesh — peer-to-peer compute market [LIVE, local only] Layer 6 Receipt-DAG + NULL — proof chain and settlement [PARTIAL — receipts anchored on mainnet] ``` The immediate build target is the wire between Layer 5 and Layer 4: NULLA nodes earn credits in a local SQLite database today. DNA x402 settles USDC on Solana. Connecting these two systems — so that compute delivered on the mesh pays out through x402 receipts — is what makes the full loop close. *** ## Status | Component | Status | | --------------------------------- | ------------------------------------------------------------------------------------------- | | x402 standard | Live, 165M+ transactions globally | | Solana x402 ecosystem | Live, 37M+ transactions | | `x402-gate` middleware | In development | | `x402-pay` client | In development | | USDC settlement | In development | | Hard spend caps | In development | | NULL token support | V2, planned | | Dark x402 access gate (on-chain) | Deployed on mainnet; program id being finalized (retired/superseded — see config (pending)) | | Dark Passport / reputation gating | **LIVE primitive on mainnet** (`9nN7…`); Passport circuits in progress | | Receipt anchoring (on-chain) | **LIVE on mainnet** (`6HSRGiv…`, `8jC8…`) | | Receipt-DAG graph | Planned | | NULLA mesh wire | Immediate build target | *** ## Related * [NULLA local mesh](/parad0xlabs-docs/nulla-local-compute-mesh/nulla-local.md) — the compute layer that DNA x402 will settle * [null-resolver](/parad0xlabs-docs/null-resolver-.null-domains/null-resolver.md) — Chrome extension for .null domain resolution * [Dark Null Protocol](/parad0xlabs-docs/dark-null-protocol-zk-privacy-and-identity/dark-null-protocol.md) — ZK identity layer * [Web0 stack overview](/parad0xlabs-docs/web0-how-it-all-connects/web0-stack.md) --- # Agent Instructions This documentation is published with GitBook. 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