x402 explained · pay-per-call · USDC on Base

What is x402?

x402 is an open payment protocol that uses the HTTP 402 "Payment Required" status code to quote and settle a payment inline with the request itself. Instead of registering an account and authenticating with an API key, software holds a small balance of digital dollars (USDC) and pays the exact quoted price the moment it asks for a resource. x402video is a pay-per-call AI video and image generation gateway built on this protocol — no account, no API key, settled in USDC on Base.

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What does the HTTP 402 status code do?

402 Payment Required has been reserved in the HTTP specification for decades, waiting for a payment standard to use it. The x402 protocol fills that gap. When a client requests a paid resource, the server replies 402 Payment Required with a machine-readable quote: the asset (USDC), the exact amount, the network (Base), and the address to pay. The client signs a payment authorization and retries the same request with the payment attached. The server verifies, settles on-chain, and returns the result.

The key idea: price discovery and payment happen inside the normal request/response cycle, with no out-of-band signup, invoicing, or key management.

How does x402video use x402?

x402video puts AI video and image models behind x402 endpoints. You POST a prompt; the gateway screens it and replies with a 402 quote; your client pays in USDC on Base; the video generates. A 5-second 720p clip starts around $0.67. Here is the flow, step by step:

POST your prompt to a generation endpoint. The gateway screens the prompt and replies 402 with a signed quote.
Pay & retry — automatically. @x402/fetch signs the USDC transfer and retries the request for you. One line of setup.
Poll the job at GET /jobs/:id (free) until status is succeeded.
Download within 24h. The response carries a signed video_url that expires, so grab it promptly.

Because there is no human step anywhere in that loop, an autonomous agent can run it end-to-end on its own.

Who is x402video for?

x402video serves two audiences on the same rails:

Developers and AI agents that need media generation without onboarding friction — buy a single clip programmatically with no account, no key, and no minimum commitment.
People, through MakeReel.xyz — the consumer-facing app built on x402video, where a wallet signs in and pays per clip on the exact same protocol.

Do I hand over custody of my money?

No. You keep your own wallet. Each 402 quote names the exact amount and recipient before anything is signed, so you can verify the charge. Payments are EIP-3009 authorizations signed locally — only the signature travels over the network — and they are gasless for the buyer, so you only need USDC, not ETH. Prompts are screened before the quote is issued, and a rejected request is never charged.

How much does x402video cost?

Pricing is programmatic: upstream model cost × markup, tracking the upstream price cards automatically. Representative reference prices (verify the live 402 quote before paying):

What	Endpoint	Price
Seedance 2.0 Fast · 5s 720p video	`POST /generate/seedance-fast/5s-720p`	~$1.05 / call
Seedance 2.0 · 5s 720p video	`POST /generate/seedance/5s-720p`	~$1.33 / call
Image — Standard	`POST /generate/grok-imagine/image`	$0.05 / image
Image — Quality	`POST /generate/grok-imagine/image-quality`	$0.10 / image

Live quotes always at api.x402video.com. See full pricing on the home page and the pricing calculator.

x402 — frequently asked questions

What is x402 in one sentence?

x402 is an open payment protocol that uses the HTTP 402 Payment Required status code to quote and settle a payment inline with the request itself — so software can pay for a resource the moment it asks for it.

What is x402video?

x402video is an agent-native, pay-per-call AI video and image generation gateway built on the x402 protocol. There is no account and no API key: each call is quoted via HTTP 402 and paid in USDC on Base, starting around $0.67 per 5-second 720p video.

How is x402 different from an API key?

With an API key you register an account, pre-pay or attach a credit card, and authenticate every request with a secret. With x402 your wallet is your identity: you hold a small balance of USDC on Base, and your client pays the exact quoted amount per request. No signup, no stored card, no rate-limit tiers. See the full comparison.

Why is x402 good for AI agents?

Autonomous agents cannot fill in a signup form or paste a credit card. x402 lets an agent discover a price (the 402 quote), pay it programmatically, and receive the result in a single automated loop — no human in the loop. @x402/fetch handles 402 → pay → retry in one line of setup.