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Stamp

Refundable paid inbox · Arc

Your attention has a price. Set it.

Strangers attach a USDC stamp to reach you. Reply and they're refunded. Spam pays you. Cold DMs and AI-agent blasts finally cost something. Real people pay nothing.

Open my inbox Try the demo inbox

Non-custodial · Immutable contract · No admin keys

Live stats from Arc

Stamps sent
Refunded to real people
Spam paid to receivers

Live from the StampBox contract on Arc0x654A…56D4 ↗

How it works

Postage for your DMs

  1. 01

    They stamp it

    A stranger writes to your link and attaches your price in USDC. It's held by the contract, not by you.

  2. 02

    You triage

    Every envelope shows its stamp. Keyboard shortcuts get you to inbox zero fast.

  3. 03

    Refund or keep

    Reply and the stamp goes back. Spam? You keep it. Ignored for 7 days, the sender can reclaim it.

Why Arc

Money that moves like messages

A $1 refundable stamp only works where money is dollars, fees are cents and finality is instant.

  • Dollars in, dollars out

    Arc pays gas in USDC. A sender needs exactly one thing in their wallet: dollars.

  • A $1 stamp makes sense

    Fees are fractions of a cent. On most chains the gas would cost more than the stamp.

  • Sub-second finality

    Deterministic finality in under a second. Sending a stamp feels like sending a DM.

  • One click, no approvals

    The stamp rides along as native USDC. No approve-then-transfer, no allowances to revoke.

For AI agents

Agents pay to reach humans

Outreach bots get a public quote API and a ready-to-sign transaction. They put down a refundable deposit, the human decides whether it was worth their time, and nobody needs an API key.

Read the developer guide 
// 1. quote + ready-to-sign tx
const q = await fetch("/api/v1/stamp?to=@alice&message=Hi")
  .then((r) => r.json());

// 2. pay in native USDC, final in <1s
await wallet.sendTransaction({ ...q.tx, value: BigInt(q.tx.value) });

Demo inbox

Send me a stamp. I'll refund you.

Say hi to the builder of Stamp. I reply to every genuine message, so your USDC comes straight back, and you get to see the whole flow end to end.

0x9802…CCD2
Try the demo inbox

Reply and they're refunded.
Spam pays you.

Pick a price, share your link. Thirty seconds, one transaction.

Set your price