Agents that scrape or call LLMs get malformed JSON, captcha pages and empty payloads. A cheap check before acting saves retries and bad decisions. Listings below are ranked by payment evidence, then relevance.
Disclosure: Payload Check is an Agentropolis kit published by Seenly, which is affiliated with Agentropolis. It is shown in its own labelled block and not ranked.
| # | Listing | Listed price | Rail | Trust | Verified buyers 30d | Uptime 30d |
|---|---|---|---|---|---|---|
| - | Payload Check — data-quality filter for agent payloads (JSON, code, scrapes, LLM output) Kit · first-party (Seenly, affiliated) Payload in → 0-100 quality score, pass/warn/fail, tags and issues before your agent uses it: broken/truncated JSON (auto-repair), JSON Schema mismatch, syntax errors, cut-off code, Source: Seenly (first-party). | $0.03 USDC per call on Base via x402 | x402 | none | 0 | n/a |
| # | Listing | Listed price | Rail | Trust | Verified buyers 30d | Uptime 30d |
|---|---|---|---|---|---|---|
| 1 | HALOWERK Agent Tools Pay-per-call API Public utility and validation APIs for software agents: data normalization, time-series analysis and traffic classification. Execution uses POST with published JSON schemas and per Source: x402-list.com. | $0.002–$0.004 per call | x402 | 78 | 36 | 99.9% |
| 2 | Toolrail Pay-per-call API Pay-per-call utility API for AI agents: PDF generation (invoice/report/contract from JSON or raw HTML), public holidays & business-day math for 187 countries, EU VAT rates for 44 c Source: x402-list.com. | $0.002–$0.01 per call | x402 | 51 | 10 | 100% |
| 3 | TaskFleet Pay-per-call API Structured-data and data-access APIs for AI agents: web search (with recency filter) via Serper+Brave failover, JS-rendering scraper to clean Markdown or schema-driven JSON, on-cha Source: x402-list.com. | $0.01–$0.25 per call | x402 | 50 | 8 | 100% |
| 4 | Data Quality Gate Pay-per-call API Clean scraped data and assess data quality before an agent acts on it. Three POST endpoints, all deterministic and LLM-free: identical input always returns byte-identical output, s Source: x402-list.com. | $0.01–$0.12 per call | x402 | 47 | 11 | 99.3% |
| 5 | Genesis Pay-per-call API Autonomous x402 machine-to-machine API providing JSON repair and normalization, web extraction, data transformation, verification, hashing, attestation, and deterministic utility s Source: x402-list.com. | $0.001–$0.03 per call | x402 | 45 | 6 | 100% |
| 6 | Blue Cap Machine Commerce Pay-per-call API Machine-readable deterministic utilities for evidence verification, schema validation, and cryptographic hashing, purchasable via x402 v2 on Base using USDC. Source: x402-list.com. | $0.01 per call | x402 | 39 | 4 | 99.4% |
| 7 | jsonguard Pay-per-call API · shares a payout wallet with other services Repair malformed JSON and validate against a JSON Schema. POST malformed JSON (and an optional schema); returns repaired text, the parsed value, and validation errors. 0.01 USDC on Source: x402-list.com. | $0.01 per call | x402 | none | 0 | 98.9% |
| 8 | MakeStack Schema text→JSON Pay-per-call API Schema text→JSON agent API — unpaid POST returns HTTP 402 with x402 PAYMENT-REQUIRED; settle Base USDC. Source: x402-list.com. | $0.01 per call | x402 | none | 0 | 99.9% |
| 9 | JSON Validator API MCP server · remote endpoint JSON syntax validation, JSON Schema checking, structure stats. x402 micropayment. Source: MCP Registry. | n/a | n/a | none | n/a | n/a |
| 10 | Jsonschema MCP server · remote endpoint JSON Schema validation MCP. Source: MCP Registry. | n/a | n/a | none | n/a | n/a |
| 11 | JSON Schema keyword count, body discarded MCP server · remote endpoint JSON Schema keyword count, body discarded Source: MCP Registry. | n/a | n/a | none | n/a | n/a |
| 12 | io.github.ryuamarines/json-schema-validator MCP server · remote endpoint Validates JSON against a JSON Schema, lists violations. x402 payment required (testnet USDC). Source: MCP Registry. | n/a | n/a | none | n/a | n/a |
| 13 | Apify Actors API Pay-per-call API · multi-endpoint (topic is one of many) · shares a payout wallet with other services Run Apify Actors (scrapers, crawlers and web automation tools) paying per call in USDC on Base via x402, with no account or API key. The 402 challenge declares a cap of 1 USDC per Source: x402-list.com. | $1.00 per call | x402 | 67 | 41 | 100% |
| 14 | Interzoid Pay-per-call API · multi-endpoint (topic is one of many) Data-quality APIs — name matching, company standardization, email validation, company intelligence. 50+ endpoints x402-payable. Source: x402-list.com. | $0.01 per call | x402 | 62 | 22 | 99.9% |
| 15 | agent-reader Pay-per-call API · multi-endpoint (topic is one of many) Two cheap, agent-native utility endpoints paid per call over x402 on Base: POST /extract turns any public URL into clean, LLM-ready Markdown with metadata (title, author, published Source: x402-list.com. | $0.005 per call | x402 | 53 | 12 | 99.9% |
| 16 | Devryno Pay-per-call API · multi-endpoint (topic is one of many) Tiny paid web services for agents. Current commerce wedge: compare merchant feed price/currency/availability with public product-page signals, audit Product/Offer JSON-LD/OpenGraph Source: x402-list.com. | $0.001–$0.05 per call | x402 | 39 | 5 | 99.9% |
| 17 | Strale Pay-per-call API · multi-endpoint (topic is one of many) Business data and compliance APIs for AI agents. 250+ independently quality-tested capabilities: company registry lookups across 20+ countries, KYB and sanctions/PEP screening, VAT Source: x402-list.com. | $0.02–$0.22 per call | x402 | none | 24 | 100% |
Machine-readable: JSON for this page · llms.txt · Corrections: hello@agentropolis.io