Pay App Portal
Learn

Guides and docs.

Start here to get the most out of U.CASH. Each guide links to the live app and its developer documentation.

How U.CASH works

The same four steps power every app. Set up once, then the whole network is one click away.

Step 01

Create one account

Sign up once at the U.CASH Portal. One login spans pay, swap, buy, names, agents, send, and verify.

Step 02

Connect your wallets

Add addresses you already control: Bitcoin xpubs, EVM, Solana, Tron, and more. Optionally add card-processor keys for cards.

Step 03

Use any app

Accept a checkout, swap a token, buy UCASH, claim a .u name, or put an agent on HTTP-402. Start anywhere.

Step 04

Funds settle to you

Money lands in wallets you control, never on U.CASH. Signed webhooks confirm each step in your own systems.

Quick start

Three things you can do in the next few minutes, right from the live apps.

Accept your first payment

  1. Sign up at pay.u.cash and create a store.
  2. Connect a wallet, such as an EVM address or a Bitcoin xpub.
  3. Add your card-processor keys if you want to take cards.
  4. Share your checkout link or embed the widget.

Open Pay →

Make your first swap

  1. Open swap.u.cash and connect your wallet.
  2. Pick the asset you hold and the one you want.
  3. Review the route and the flat 0.30% fee.
  4. Sign once; the output lands in your wallet.

Open Swap →

Buy UCASH

  1. Open buy.u.cash.
  2. Choose how much UCASH to buy.
  3. Pay with any asset you hold, swapped at market price.
  4. UCASH settles to your wallet on Ethereum, Polygon, or Base.

About UCASH →

Guides

Accept crypto and cards

Set up a checkout, connect wallets, add a card processor, and get paid. Open Pay →

Swap across chains

Trade 30+ chains non-custodially and understand the 0.30% fee. Networks →

Buy UCASH

Buy the network access and loyalty token in one step, non-custodial. About UCASH →

Claim a web3 name

Get a .u or @u name and point it at your wallets. Names →

Build agent payments

Put an AI agent on HTTP-402 and sell per request. Agent docs →

Integrate a store

Install a plugin or use the universal embed. Plugins →

Developer documentation

Concepts

Non-custodial

U.CASH never holds your funds or your keys. Payments settle straight to wallet addresses you control, so there is no central pool to lose. See Technology.

Converters

Retail merchants who use U.CASH Pay to move cash and crypto for customers in person, a real-world on and off ramp alongside the digital rails. See Network.

HTTP-402

The standard that turns any URL into a priced resource. An agent gets a 402 Payment Required, pays, retries, and gets through automatically. See Agents.

UCASH

The network access and loyalty token of the ecosystem: an ERC-20 on Ethereum, Polygon, and Base, used for access, discounts, and rewards. See UCASH token.

Web3 names

Human-readable identities like .u and @u that resolve to a wallet address, so you can pay a name instead of pasting hex. See Names.

Settlement

The moment a payment is final on its chain. You set confirmation policies per coin to balance speed against finality. See Technology.

Have a question? Check the FAQ or contact us.