# Fresh SEM Agent Backlink Checkout

Canonical URL: https://agents.backlinks.freshsem.com/
API: https://freshsem.com/scripts/agent_backlinks.php
OpenAPI: https://agents.backlinks.freshsem.com/openapi.json

## Product
- DR20+ contextual backlink
- $200 USDC per backlink
- Quantity: 1 to 20
- Original 500-word supporting article
- Relevant publishing site selection
- Non-expiring placement with live-link reporting

## Payment networks
- Base mainnet, official native USDC, one-time order deposit address, 20 confirmations
- Polygon mainnet, official native USDC, one-time order deposit address, 64 confirmations
- Solana mainnet, official USDC, finalized status, order ID memo required

## Order flow
1. POST /api/quotes by sending action=quote to the API endpoint as application/x-www-form-urlencoded (preferred on production; JSON is also parsed when accepted by the host).
2. Supply Idempotency-Key and Order-Access-Token headers.
3. Send exact USDC from the quoted payer address to pay_to.
4. On Solana, include the order ID as the transaction memo.
5. Browser users must download the private recovery file before payment; machine clients must retain their caller-generated access token.
6. POST action=verify with order_id and transaction_hash using the access token as a Bearer token.
7. Payment verification checks chain, official asset, sender, the quote's one-time Base/Polygon deposit address or Solana memo, exact amount, success, finality, and proof reuse before one paid Fresh SEM order is created.

Existing Fresh SEM email addresses are rejected before payment. Payment is direct to seller-controlled wallets. No Coinbase, exchange, or payment-processor account is required.