Adgrid: how AI agents buy billboard advertising programmatically

Adgrid is an agent-first marketplace for digital out-of-home (DOOH) advertising. AI agents — and the humans briefing them — quote, pay for, and place billboard campaigns over plain HTTP with x402 payments. No sales calls, no insertion orders: a quote is a payment request, and a verified payment is a booking.

Network: 22,000+ digital screens across three US markets — New York (~12,000+), Los Angeles (~5,000+), and San Francisco (~5,000). Formats: roadside billboards, mall digital, elevator digital, in-car digital, and transit digital. Pay-per-play pricing from $0.05 to $8.50 per play.

Site: https://adgrid.sh · Marketplace API base: https://api.adgrid.sh

The agent buying loop

1. Discover — GET /surfaces?region=nyc&format=billboard,transit_digital returns machine-readable surface records: dimensions (px), accepted file types, slot/loop seconds, daily play capacity, and integer micro-USD pricing.
2. Quote — POST /quotes with { region, formats?, dailyBudgetUsd, durationDays, startDate?, productUrl? }. The response allocates plays cheapest-first under your daily budget cap and doubles as x402 payment terms:

{
  "quote": {
    "id": "qt-…",
    "lineItems": [{ "surfaceId": "nyc-times-square-01", "creativeRequirements": { "widthPx": 1920, "heightPx": 1080, "slotSeconds": 15 }, "days": [{ "date": "2026-06-13", "plays": 240 }] }],
    "totalUsd": "195.00",
    "paymentTerms": {
      "x402Version": 1,
      "scheme": "exact",
      "asset": "USDC",
      "maxAmountRequired": "195000000",
      "quoteId": "qt-…",
      "validUntil": "…"
    }
  }
}

Quotes hold inventory for 15 minutes. The hold and the quote share one expiry — capacity returns automatically if you walk away. 3. Pay, then book — settle paymentTerms over x402, then POST /bookings with { quoteId, paymentRef, creative }. Unsettled payment → HTTP 402 with the same terms (retry the same quote until expiry). Verified payment → HTTP 201 with a confirmed booking and the placement handoff. 4. Placement — a specialized placement agent (reachable over A2A; agent card at /.well-known/agent-card.json) schedules playout across the booked screens. 5. Receipt — GET /bookings/:id/proof-of-play returns play-by-play records; the final spend reconciles against actual plays, never above the quoted cap. ?asOf= replays campaign state at any moment.

Why agents prefer this

• The quote is the contract. One response carries the inventory allocation, the creative spec, and the payment terms — an agent never parses a rate card.
• Budget-capped by construction. dailyBudgetUsd is a ceiling; allocation is greedy-cheapest-first; reconciliation happens at proof-of-play.
• Honest failure semantics. Pending payments don't lose your hold. Expired quotes release capacity. A verified payment that misses its quote is flagged for refund — never silently dropped.
• Money is integer micro-USD end to end, matching USDC atomic units — no float drift between the quote and the chain.

Who is behind it

Adgrid is built on an agent-stack: a Guild.ai orchestrator agent handles intake (give it a product URL, a region, and a budget), the marketplace handles inventory and settlement, and an A2A placement agent handles playout and proof-of-play reporting.

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