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Dexter Ships x402 Config Lint Engine in SDK Debug Page

Dexter Ships x402 Config Lint Engine in SDK Debug Page

FOR IMMEDIATE RELEASE

Real-Time Protocol Validation, Format Detection, and Agent Discovery Analysis — Built Into the Debug Page Developers Already Use

Paste a URL. Get a full spec compliance report before you ship.

The Problem With Shipping x402 Endpoints Today

FEBRUARY 2026 — Building an x402-enabled API endpoint means getting dozens of details right: the correct version field, CAIP-2 network identifiers, properly formatted payment addresses, amount fields in the right type, and — increasingly — Bazaar discovery extensions so AI agents can find and call your API automatically.

Until now, the only way to check was to deploy and hope. Facilitators would reject malformed configs silently. Agents would skip endpoints with no discovery schema. Developers had no feedback loop.

Dexter today announces a built-in x402 config lint engine in the SDK Debug Page — the same page developers already use to test facilitators, compare protocol versions, and run live settlements.

What It Does

Format Detection That Actually Understands Backward Compatibility

The lint engine does not simply check if x402Version equals 2. It independently analyzes both the PAYMENT-REQUIRED header and the response body, detects the format of each (v2, v1, flat, or unknown), and then performs compatibility analysis:

  • v2 header + v1 body → Hybrid. Intentional backward-compat — v2 clients read the header, v1 clients read the body. Both paths work.
  • v2 header + no body → Header-only. Fine for v2 clients, but v1 clients get nothing.
  • v1 body + no header → Legacy. v2 clients looking for the PAYMENT-REQUIRED header will not find it.
  • Both match → Consistent. Clean.

This is not a boolean pass/fail. It is an explanation of what works, what does not, and why.

14 Structural Validation Checks

Every field in the 402 response is validated with specific error codes and field paths:

CheckWhat It Catches
MISSING_VERSIONNo x402Version field
NETWORK_NOT_CAIP2Using "solana" instead of "solana:5eykt4UsFv8P..."
INVALID_SOLANA_ADDRpayTo address is not valid base58
INVALID_EVM_ADDRpayTo address is not valid 0x hex
V1_ONLY_AMOUNTOnly maxAmountRequired present, missing amount for v2
AMOUNT_MISMATCHamount and maxAmountRequired both present but different
AMOUNT_NOT_STRINGamount is a number instead of string
RELATIVE_RESOURCE_URLresource.url is "/api/endpoint" instead of a full URL
MISSING_PAY_TONo payment address at all
MISSING_NETWORKNo chain specified
MISSING_ASSETNo token contract address
MISSING_SCHEMENo payment scheme (defaults to "exact")
AMOUNT_COMPATBoth amount fields present and match — full v1+v2 compat confirmed
FLAT_FORMATLegacy flat format with no accepts array

Each issue includes severity (error, warning, info, or pass), a monospace field path like accepts[0].payTo, and a human-readable message.

Agent Discovery & Bazaar Schema Explorer

The v2 spec includes extensions.bazaar — the standard way AI agents learn how to call your API before paying. The lint engine checks for its presence and structure:

  • Full Bazaar (info + schema) → Agents can auto-discover your API. Green.
  • Partial Bazaar (missing info or schema) → Agents get incomplete picture. Amber warning.
  • Legacy outputSchema only → Works but not the standard going forward. Blue info.
  • Nothing → Agents have no idea what parameters to send. Red warning.

When Bazaar extensions are found, the debug page renders them as expandable JSON viewers — the info section (showing an example request/response agents use at a glance) and the schema section (the JSON Schema contract agents validate against). Developers can inspect exactly what agents will see.

How It Works

  1. Paste any x402 endpoint URL into the SDK Debug Page
  2. The page auto-probes both GET and POST, decodes the 402 response
  3. The lint engine runs instantly — analyzing the PAYMENT-REQUIRED header and response body
  4. Results appear inline: format badge, compat analysis, expandable lint issues, and Bazaar explorer

No signup. No CLI install. No separate tool. It is part of the same debug page where developers already test facilitator compatibility and run live payments.

Built On What Already Exists

This is not a standalone tool. It extends the SDK Debug Page that already offers:

  • Facilitator Leaderboard — Compare all 14+ x402 facilitators at once
  • SDK vs API Comparison — See which facilitators work with the SDK endpoint vs the Dexter API hybrid response
  • Live Settlement — Verify and settle payments through any compatible facilitator
  • Protocol Analysis — Decoded 402 response field inspection with spec compliance notes
  • Smart URL Input — Auto-detects methods, pricing, and chain info on paste

The lint engine adds the missing piece: structural validation before you go live.

About Dexter

Dexter is payment infrastructure for the AI economy. Operating on Solana, Base, Polygon, Arbitrum, Optimism, and Avalanche, Dexter's x402 facilitator has processed 3.5M+ autonomous settlements. From facilitation to marketplace to trust layer, Dexter handles the complete payment stack for machine-to-machine commerce.

  • Dexter Facilitator: x402 payment settlement across 6 chains
  • Dexter Marketplace: Discover and monetize AI services
  • Dexter Trust Layer: ERC-8004 identity and AI-powered reputation
  • Dexter MCP: 70+ AI tools via Model Context Protocol
  • Dexter Lab: Deploy and monetize x402 APIs with managed wallets
  • Dexter SDK: @dexterai/x402 npm package for building paid endpoints

$DEXTER | dexter.cash | @dexteraisol

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Media Contact: [email protected]

The SDK Debug Page is a free developer tool. No payment or authentication required to use the lint engine, facilitator comparison, or protocol analysis features.