Knowledge & memory: MCP servers, A2A agents and x402 APIs

• agent.halowerk.com Live x402

  Takes two state documents — target (what the twin should look like) and observed (what was measured) — and returns a leaf-by-leaf comparison. Every leaf path carries one of five states: in_tolerance, out_of_tolerance, m…

  x402 paid API · 3 endpoints · check 88/100

• aialign.halowerk.com Live x402

  Calculates each group positive-outcome rate, compares it with an explicit or automatically selected reference group, and reports rate differences and selection-rate ratios. Aggregate disparity metrics do not establish d…

  x402 paid API · 10 endpoints · check 88/100

• billionaireorder.com Live x402

  For AI agents building agent swarms, synthetic users, NPCs, or trading bots. Input: archetype + prompt (e.g. 'risk-taking crypto founder'). Output: OCEAN Big Five + Dark Triad + trading psychology vector with emotional…

  x402 paid API · 6 endpoints · check 88/100

• intel.halowerk.com Live x402

  q verwendet echtes SQLite FTS5, zusätzlich stehen Namespace und Tagfilter bereit. Die verifizierte Zahleradresse ist der Eigentümer; Ergebnisse und gespeicherte Daten sind strikt auf diesen Zahler begrenzt. (6 paid endp…

  x402 paid API · 6 endpoints · check 88/100

• mpp.tracefast.xyz Live x402

  TraceFast knowledge graph: what an Ethereum address is, as proven facts — wallet or contract, proxy and upgradeable or not, a token and its standard, and for a token contract whether it can pause, mint or blacklist and…

  x402 paid API · 12 endpoints · check 88/100

• payload402.edgebytenet.workers.dev Live x402

  Convert amounts between ISO 4217 currencies using ECB daily reference rates (Frankfurter). Use for invoices, travel budgets, expense reports, and shopping comparisons when you need a verifiable rate instead of LLM arith…

  x402 paid API · 4 endpoints · check 88/100

• staging.toolkit.dev Live x402

  Add a new memory. This method is called every time the user informs anything about themselves, their preferences, or anything that has any relevant information which can be useful in the future conversation. This can al…

  x402 paid API · 1 endpoint · check 88/100

• aarn.space Live x402

  Read one public webpage URL and return clean, LLM-ready Markdown or plain text. Designed for AI agents that need webpage contents, RAG context, research or summarization. (2 paid endpoints on api.aarn.space.)

  x402 paid API · 2 endpoints

• agents.daedalusdevelopmentgroup.com Live x402

  DDG agent-payable service request (248 paid endpoints on agents.daedalusdevelopmentgroup.com.)

  x402 paid API · 12 endpoints

• agents.forwardlane.com Live x402

  Searches repository names and properties. Returns a paginated envelope with items, total, page, page_size, and total_pages, sorted by composite score. (25 paid endpoints on agents.forwardlane.com.)

  x402 paid API · 12 endpoints

• agentwholesale.vercel.app Live x402

  Search the live web for current information. Returns fresh structured organic search results with titles, URLs, snippets, domains, and ranks for agent research and retrieval. (2 paid endpoints on agentwholesale.vercel.a…

  x402 paid API · 2 endpoints

• aispace.bot Live x402

  Text-to-image generation on Venice models (Flux, SD3.5, GPT-Image, HunyuanImage, and more), paid per request in USDC on Base via x402, no API key. Resolve a model id from GET /api/v1/models?type=image and an optional st…

  x402 paid API · 11 endpoints

• charliemorrison.dev Live x402

  Web-content reader: fetch any http(s) URL and return clean readable text, title/description/canonical, and outbound links as JSON — the data an agent ingests on each step of a crawl or RAG loop. Input: url. (3 paid endp…

  x402 paid API · 3 endpoints

• embed.gedx402.com Live x402

  Rerank documents against a query with BGE Reranker Base (@cf/baai/bge-reranker-base). POST query plus documents[]; returns relevance scores for search and RAG pipelines.

  x402 paid API · 1 endpoint

• erb-llm.com Live x402

  Privacy-first chat API: prompts run on a local open-weight model on dedicated hardware - your data is never forwarded to OpenAI/Anthropic or any third-party LLM cloud. OpenAI-compatible chat completions: summarize, draf…

  x402 paid API · 5 endpoints

• familyofficeknowledgegraph.ai Live x402

  The Family Office Knowledge Graph index of record for $0.01 USDC — every node's record list (LEI, legal name, aliases, register ids, field states, as-of) as a signed statement (EdDSA, kid fo-kg-x402-2026-09) with a rece…

  x402 paid API · 1 endpoint

• forwardlane.pay.zeroclick.io Live x402

  The most recent quality snapshot for the repository. Returns 404 if no snapshot exists. (9 paid endpoints on forwardlane.pay.zeroclick.io.)

  x402 paid API · 9 endpoints

• gamemaxxing.baes.so Live x402

  Search GAMEMAXXING's video games and gaming knowledge base for game concepts across game design, game business, game culture, and gaming history, then return ranked JSON hits with full content first and source URLs seco…

  x402 paid API · 1 endpoint

• madoromi.fun Live x402

  Japanese dream-interpretation agent API. Returns a Gemini-generated full interpretation from madoromi's curated dream-motif knowledge base (result schema agent-dream-insight.full.v1). Japanese output only. Dream text is…

  x402 paid API · 1 endpoint

• marketplaceforaiagents.com Live x402

  Google Search API: Give a query, get ranked organic results with title, link, snippet, plus knowledge graph and related searches. $0.003 USDC per call on Base. (2 paid endpoints on marketplaceforaiagents.com.)

  x402 paid API · 2 endpoints

• mcp.whitemagic.dev Live x402

  WhiteMagic hosted recall: read-only hybrid memory search (BM25 + vector + associative) over a curated public corpus for agent continuity. Call when an agent needs durable context from prior sessions or the public knowle…

  x402 paid API · 1 endpoint

• midax402.com Live x402

  MIDAX402: Evidence+ x402 intelligence with expanded corpus retrieval, local risk brief, contradiction scan and concrete action plan. We do not grade our own answer: the verdict is answered or needs_more_data (grounded i…

  x402 paid API · 1 endpoint

• particle.pro Live x402

  Search entities. Find a person, company, or knowledge graph entity by free-text query — a name, partial name, nickname, stock ticker, @handle, or website domain. (19 paid endpoints on api.particle.pro.)

  x402 paid API · 12 endpoints

• posttosource.com Live x402

  Convert a Twitter/X, LinkedIn, Medium, Substack, Beehiiv, or public Notion page URL into clean markdown.

  x402 paid API · 1 endpoint

• robbiegeorgephotography.com Live x402

  Atomic canonical resolution for the registered Robbie George Biography Plate™ identifier. x402 payment grants one endpoint-level retrieval only. It does not grant training, embedding, bulk ingestion, redistribution, res…

  x402 paid API · 1 endpoint

• scopeapi.dev Live x402

  Generate text embeddings and semantic embedding vectors using OpenAI text-embedding-3-small for vector search, semantic similarity, clustering, retrieval, and RAG workflows. (12 paid endpoints on scopeapi.dev.)

  x402 paid API · 12 endpoints

• ta.lonestaroracle.xyz Live x402

  Multi-timeframe analysis — all 4 timeframes (15m, 1h, 4h, 1d) with confluence score and AI summary (2 paid endpoints on ta.lonestaroracle.xyz.)

  x402 paid API · 2 endpoints

• web.tollkit.dev Live x402

  PDF to text: give a PDF URL, get the text of every page with the title, author and page count. For RAG, research and summarizing reports, filings and papers. (6 paid endpoints on web.tollkit.dev.)

  x402 paid API · 6 endpoints

• wiki.use.x402atlas.com Live x402

  Wikipedia article summary — plain-text and HTML extract, short description, thumbnail and Wikidata id for any title, in a clean normalized envelope with CC-BY-SA attribution.

  x402 paid API · 1 endpoint

• x402-data-api.onrender.com Live x402

  IP geolocation: country, region, city, coordinates, and timezone for any IPv4 or IPv6 address. Fast in-memory lookup for analytics, fraud, and personalization agents. (2 paid endpoints on x402-data-api.onrender.com.)

  x402 paid API · 2 endpoints

• x402-trends-server.onrender.com Live x402

  Scrape a public webpage and extract clean readable text. Use this web scraping endpoint when an AI agent needs page content for summarization, research, retrieval, content extraction, indexing, or downstream analysis wi…

  x402 paid API · 4 endpoints

• xhagents.xyz x402

  Ask the XH Agents knowledge base (15 field notes on infrastructure, x402 and agent tooling) (24 paid endpoints on xhagents.xyz.)

  x402 paid API · 12 endpoints · check 88/100

Related capabilities

x402 paid APIsAI models & inferenceResearchAgent infrastructureEmailDocuments & PDFsVideo & audioCoding & dev tools

How to use one

MCP servers plug into Claude, ChatGPT, Cursor and other AI clients; A2A agents take tasks over JSON-RPC; x402 APIs charge per call in USDC with no account. Guides: A2A vs MCP · How to call an A2A agent · x402 for agents.

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