On-chain marketplace · USDC on Base · No accounts
Buyers pay per call in USDC, a digital US dollar. Sellers earn directly to their wallet. Agents plug in with one HTTP request. No accounts, no API keys, no chargebacks — your wallet handles the crypto for you.
Free to test — fund any wallet from the Base Sepolia faucet.
ChefBot Kitchen
recipe-suggest
{
"recipe": "Garlic-spinach pasta",
"minutes": 12,
"steps": 5
}API Wrappers
weather
{
"temperature_c": 18.4,
"humidity_pct": 62,
"wind_mps": 4.1
}Pixel Press
qr-code
{
"kind": "qr-code",
"url": "https://.../qr.png",
"content_type": "image/png"
}7
Shops
33
Products
6
Reviews
6
Verified purchases
Featured
Shields-style status badge as SVG — label, message, colour customizable.
Pixel Press $0.003
per call
Generate a downloadable QR-code PNG for any string. Size configurable.
Pixel Press $0.005
per call
Classify text as positive, neutral, or negative with confidence + reasoning.
AI Claude Shop $0.03
per call
Fetch a web page and return a structured summary with key points.
AI Claude Shop $0.08
per call
Verifiable dice roll with NdM+K spec (e.g. 2d20+5). Returns rolls + total.
Oddities $0.003
per call
Render an ASCII-art banner from a short string. 5-row block font.
Oddities $0.004
per call
Use cases
Six concrete ways the marketplace gets used today — from agentic shopping to selling generated assets one piece at a time.
AI agents
Wire the obolium MCP server into Claude Desktop (or any MCP client) and your agent gets a budget-capped wallet plus live discovery of every paid endpoint. No per-tool API key management.
Indie developers
Stop signing up for trial accounts to test ideas. Fund a burner wallet once, then pay fractional cents per call to every API you need. Bills are denominated in dollars; receipts are auditable.
API owners
Wrap any HTTP endpoint in seller-svc. No Stripe integration, no chargeback risk, no API-key issuance, no support tickets for failed cards — USDC settles instantly to your wallet.
Content + media sellers
Markdown articles, HTML reports, audio essays, generated images — set a USDC price per fetch. Buyers see the result rendered natively in the browser; you keep the work behind a paywall without a subscription system.
Generative artists
Image generators, QR codes, badges, ICS invites. Each call is paid + receipted; you keep the model, the marketplace handles billing and discovery. Results return either inline JSON or a downloadable URL with content_type set.
AI service builders
Ship an MVP for fractional cents, watch who pays, raise the price when ratings come in. Reputation is anchored on chain to real payments — early adopters' reviews carry weight forever, not just until you change platforms.
Marketplace
Download-kind assets on demand — QR codes, barcodes, status badges. Pay per generation; output URLs are stable and embeddable.
Three Claude-backed prompts wrapped as paid x402 endpoints — sentiment, code review, URL summarization.
Misc-kind utilities — .ics calendar invites, dice rolls, ASCII banners. Single-purpose, deterministic, fun.
Thin paid wrappers around free public APIs — weather, crypto price, IP geo. One billing relationship instead of N signups.
Cooking and food services on obolium.
Writing assistance for agents — paraphrase, headline, tone-shift, grammar, summaries. Pay per call.
How it works
Every purchase is a single on-chain USDC transfer through an immutable Solidity contract. No platform middleman holds your funds.
USDC
A stablecoin pegged 1:1 to the US dollar, issued by Circle. Held in a self-custodial wallet. 1 USDC always = $1.
Base
An Ethereum Layer 2 by Coinbase. Same security as Ethereum, ~$0.0001 per transaction so micro-payments are practical.
No accounts
Your wallet address is your identity. No signup, no API keys, no chargebacks — what you sign is what you pay.
Pick a paid endpoint. Each shop publishes a manifest listing its capabilities, input schemas, and per-call price in USDC.
Read-only · no wallet needed yet
Your wallet signs one USDC transfer. A marketplace contract atomically splits it — 97% to the seller, 3% to the marketplace.
splitter.pay() · ~$0.0001 gas on Base
The endpoint runs your request and returns the result plus a signed receipt that ties the response to the on-chain payment.
EIP-712 receipt · verifiable forever
Optionally publish a 0–5 rating tied to your payment tx. Reputation lives on chain — portable, verifiable, no platform lock-in.
reputation.rate(...) · one rating per payment
The splitter contract
When you pay $0.10 USDC, the marketplace's immutable Solidity contract atomically routes $0.097 to the seller and $0.003 to the marketplace treasury in a single on-chain transaction. No escrow, no settlement period, no hidden fee tier.
Buyer
$0.10
Seller 97%
$0.097
Market 3%
$0.003
Safe + transparent
Self-custody, immutable contracts, signed receipts, automatic refunds, and an open codebase — the guarantees are properties of the system, not promises from us.
The marketplace never holds your USDC. Funds move from your wallet straight to the seller in one transaction — there is no escrow account we can freeze or drain.
wallet → seller, one tx
The splitter and reputation contracts are deployed Solidity with no admin keys, no upgrade proxies, no pause switches. The 97/3 split and rating rules cannot be changed after deploy.
No proxy, no admin, no upgradeability
Every successful purchase returns an EIP-712 receipt signed by the seller. Anyone can verify on chain that the payment tx, the input, and the response are bound to that signature.
EIP-712 typed data
If a seller endpoint errors after payment, the seller wallet automatically broadcasts a USDC refund back to the buyer. The refund tx hash is recorded in your /orders so the trail is auditable.
On-chain refund · idempotent by payment_tx
Contracts, marketplace API, seller-svc, and this website are open source. The reputation graph is readable from any client — nothing here requires our marketplace to keep working.
gitea.hubje.nl/brian/obolium
For sellers
Wrap your existing API in seller-svc. Set per-call prices. Earn USDC directly to your wallet. The marketplace handles discovery and reputation.
For developers
Standard x402 wire format. SDKs and a CLI for buyers; an MCP server for AI agents. No proprietary glue.
# Pay a capability with x402 + USDC on Base.
$ curl -X POST https://api.chefbot.example/recipe-suggest \
-H "x-payment: $X402_BASE64" \
-d '{"ingredients": ["pasta", "garlic", "spinach"]}'
{ "recipe": "Garlic-spinach pasta in 12 minutes...",
"receipt": { "tx": "0xabc...", "amount_usdc": "0.10" } }x402 for payments. JSON manifests for discovery. Solidity contracts on Base. The marketplace is just one client of the data — anyone can build another.