x402-gateway — 43 Pay-Per-Call APIs for AI Agents (USDC on Base)
**43 pay-per-call APIs for AI agents — blockchain data, web scraping, document/PDF-to-Markdown conversion, ZK proof verification, image & 3D model generation, QR/diagram/OG-image rendering, LLM chat, gift cards, short links, ephemeral webhook receivers. Settled in USDC on Base via the x402 payment protocol.** No accounts, no API keys: agents pay per request via the x402 protocol.
Pay-per-call MCP.
No accounts. No logins. No keys.
43 tools on Base via the Coinbase CDP x402 facilitator. Agents pay per request in USDC — settled on-chain in seconds. No API keys to provision, no subscriptions to manage.
How it works
The x402 protocol turns HTTP 402 Payment Required into an onchain payment flow.
Agent reads metadata
GET the endpoint. Receive an OpenAPI spec + x402 payment details (payTo, amount, asset, network).
Sees 402 response
Server returns HTTP 402 with a signed payment requirement in USDC on Base or Solana.
Signs & pays onchain
Agent wallet broadcasts a USDC microtransaction on Base. No human needed, no account to create.
Gets the result
Server verifies the payment header and returns the API response. Done.
All APIs
Each tool is a standalone paid endpoint. Browse the catalog — click any card for details.
Fetch a URL and convert its main content to clean, LLM-ready Markdown. Strips nav/ads/sidebars.
Get the live USD price of any token by symbol (e.g. BTC, ETH, SOL, PEPE).
Get a complete wallet portfolio: native ETH balance, ERC-20 balances, NFT holdings, recent transfers.
Scan recent blocks for large ETH transfers involving an address. Filter by direction and threshold.
Aggregate native balance and token/NFT counts for an address across eth, arb, base, polygon, opt.
Diff two OpenAPI specs and generate a structured breaking-change changelog. Deterministic, no LLM.
Diff git commits and generate a structured breaking-change changelog. Provide repo URL + base commit.
Render a Mermaid diagram to an image (PNG or SVG). Returns base64-encoded image.
Convert an HTML string to clean, LLM-ready Markdown. Handles headings, links, tables, code blocks.
Generate a QR code or barcode as an image (SVG or PNG). QR, Code128, EAN, UPC, ISBN, and more.
Generate an Open Graph social-card image (1200x630 PNG) from a title and description.
Search live job postings by keywords and locations. Returns structured results: title, company, location, salary, and more.
Verify a Semaphore ZK proof locally using Groth16 (embedded official vkey). No external dependency — pure on-device verification.
Verify a World ID 4.0 proof via the Worldcoin Developer Portal API. Generates RP signature, proxies to Worldcoin, returns nullifier + validity.
Batch verify up to 10 Semaphore proofs in a single request. Returns per-proof results with timing stats.
Verify a Sign-In-With-Ethereum (EIP-4361) signature as a paid oracle: returns wallet address + chainId, mints nothing.
Verify a NIP-98 Nostr HTTP auth event with replay protection (each event id verifies once). Returns the signer pubkey.
Verify an ed25519 Solana wallet signature over a nonce-bearing message. One verification per nonce; returns signer pubkey.
Convert an Ethereum address to its EIP-55 checksummed form — required on SIWE message line 2 before signing.
Chat with a language model. OpenAI-compatible /v1/chat/completions. 50+ models — free (auto, eco, premium) are $0, paid models at cost.
Convert a PDF document to clean, LLM-ready Markdown. Direct URL or base64 file bytes. Reports, papers and contracts become RAG-ready text.
Convert a DOCX (Word) document to Markdown. Contracts, resumes, reports and letters — headings, lists and tables preserved.
Convert a PPTX (PowerPoint) presentation to Markdown. Each slide becomes a heading — pitch decks turn into LLM-readable text.
Convert XLSX or CSV to a Markdown table AND a JSON array of row objects in one call. All sheets included, flattened in order.
Convert an EPUB e-book to Markdown. Chapters become headings; metadata included — feed whole books into LLM context.
Convert any document to Markdown with automatic format detection — pdf, docx, pptx, xlsx, csv, epub, html, text. One endpoint for all of them.
Verify a stablecoin: issuer identity, GENIUS Act qualification status, and latest reserve attestation. Resolves the token from chain+address, a known symbol, or a tx hash. Free preview validates the input and returns the issuer only.
Buy a digital gift card code (Foot Locker, Target, AMC, 1000+ brands). Search the catalog free, pay the face value + fee in USDC — code delivered instantly, settled on Base via x402.
Create a permanent short link on freeq.one (custom or random slug, optional TTL expiry). Returns the short URL plus a one-time manage_secret that gates free stats and deletion of the link.
Click stats for a freeq.one short link: total clicks and last-30-day daily counts. Free for the link owner (pass the manage_secret); paid calls serve agent link-verification flows.
Ephemeral webhook receiver: creates a single-use HTTPS URL that catches any POST (Stripe, GitHub, internal) for up to an hour. Sender ingest is free; reads are $0.01, +1h extends are $0.05. In-memory, auto-deletes on expiry.
RaaS — Referral-as-a-Service: short-link referrals that turn verified on-chain x402 payments on Base into service credits. Provision a project with one paid x402 call to /tools/raas_project_provision ($0.05, one-time) and get back a project_id plus an API key; mint links at freeq.one/{code} and read stats with that key at no extra cost. Rewards are credits redeemable for API access, never USDC.
Live Google organic results for any keyword. Returns top 10 titles, URLs, snippets, and rank. Priced below typical SEO-data APIs.
Google search volume, CPC, and competition for up to 100 keywords. Priced below typical SEO-data APIs.
Generate keyword ideas from a seed keyword with volume data. Priced below typical SEO-data APIs.
Find organic competitors for any domain. Priced below typical SEO-data APIs.
Get all keywords a domain ranks for with position and volume. Priced below typical SEO-data APIs.
Backlink overview for any domain — referring domains, backlink count, authority. Priced below typical SEO-data APIs.
Detect search intent (informational, transactional, commercial) for a keyword. Priced below typical SEO-data APIs.
Text-to-image generation (fast tier, 2-6s). Returns a permanent hosted image URL. Game assets, avatars, illustrations, concept art.
Premium text-to-image generation (10-30s) — better prompt adherence and typography. Returns a permanent hosted image URL.
Photo to 3D model (fast tier, 10-30s). Single 2D image URL to a textured low-poly GLB mesh + preview thumbnail. Game-ready — Three.js, Unity, Godot.
Photo to 3D model (high-detail tier, 1-3 min). High-poly textured GLB with PBR-like shading + preview thumbnail. Game-ready — Three.js, Unity, Godot.