X402

Browser Use Cloud — pay with x402 (crypto wallet)

This is a scripted flow. Follow the steps in order. x402 only works through the SDK (browser-use-sdk for Python, the browser-use npm package for TS) — there is no browser-use CLI command for it, so every step runs a short SDK script.

How to use this script

• Lines under Say: are spoken to the user word for word. Don't paraphrase, add, or drop anything.
• <like this> inside a Say block is a fill-in — replace it with the real value, keep the rest exact.
• Lines under Ask: use the AskUserQuestion tool. Use the question and option text exactly as written.
• To show an explanation before a question, put it inside the AskUserQuestion question field (it renders above the options). Don't send it as separate chat text before calling the tool — that text gets dropped when the question UI opens. So: explanation + the actual question both go in the question field, in one tool call.
• Lines under Do: are your actions. Don't read them out.
• Track two facts as you go: SETUP (A or B, from Step 1) and MODE (A or B, from Step 2).
• SETUP, MODE, and the Path A/B/C names are internal labels for you only. Never say them to the user. Describe choices in plain words instead (e.g. "top up your account" / "accountless wallet"), never "Mode B" or "Path A".

Step 1 — Open and pick the setup

Ask: (header: Use x402) — put the explanation and the question both in the question field, exactly:

x402 is a protocol from Coinbase that, instead of presenting an API key, allows you to use crypto to pay for API requests. x402 lets you pay Browser Use per request from a crypto wallet with USDC on Base — no signup, API key, or credit card needed, just a wallet. Setup takes a few minutes: get or make a wallet, add funds, save the key in .env, and test it.

How do you want to use x402?

• Just use it — Run Browser Use tasks, paid from your wallet, here in terminal by asking me. I set up the wallet and key.
• Build it in — You're coding an app and want x402 in it. I will help you install the SDK, save the key to your project's .env, and add code.

Do: "Just use it" → SETUP = A. "Build it in" → SETUP = B.

Step 2 — Find the account (check before asking)

Do: Look for an existing Browser Use API key, in this order. Don't say anything yet.

1. BROWSER_USE_API_KEY in the environment
2. a BROWSER_USE_API_KEY= line in ./.env
3. ~/.browser-use/config.json (saved by browser-use cloud login / signup)
4. browser-use doctor output, if the CLI is installed

If no key is found anywhere:

Say:

No Browser Use key found, so I'll set this up accountless: the wallet is your identity, and the first payment makes a project named after it.

Do: MODE = A. Go to Step 3.

If a key is found:

Ask: (header: Account) — question: I found a Browser Use API key in <location>. Where should the USDC credits go?

• Top up that account — Credits go to your existing API key's project. Good if your free credits ran out, or you'd rather pay with crypto than a card.
• Accountless wallet — The wallet is a separate identity. The first payment makes a fresh project named after the wallet, apart from your existing account.

Do: "Top up that account" → MODE = B. "Accountless wallet" → MODE = A.

Step 3 — Wallet

Ask: (header: Wallet) — question: Do you have a wallet ready, or should I set one up?

• I have a funded wallet — An EVM wallet (MetaMask, Rabby, Coinbase Wallet, Frame, Phantom, …) with USDC on Base mainnet.
• Walk me through it — I'll guide you through making a wallet, adding Base, and buying USDC.
• Make a fresh one — I'll generate a throwaway wallet for automation. You'll still need to fund it.

Branch on the answer.

Path A — "I have a funded wallet"

Do: Check .env is in .gitignore; add it if missing.

Ask: (header: Add key) — put the note and the question both in the question field:

Your wallet's private key needs to go into .env. You can paste it here and I'll add it for you, or add it yourself. Heads up: anything pasted in chat is saved in the transcript, so for a high-value wallet, adding it yourself is a bit safer. How do you want to do it?

• Paste it here — Paste your private key in the chat and I'll write it to .env for you.
• I'll add it myself — You add it to .env, then send me just your public address.

If "Paste it here":

Do: Write BROWSER_USE_X402_PRIVATE_KEY=<pasted key> to .env (create the file if needed; make sure .env is gitignored). Never echo the key back or print it anywhere.

Say:

Saved your key to .env — I won't print it back.

Do: Go to Step 4.

If "I'll add it myself":

Say:

Add this line to your .env, then send me your wallet's public address (the 0x… one — safe to share):

BROWSER_USE_X402_PRIVATE_KEY=<your private key>

Do: When they send the address, check it matches ^0x[0-9a-fA-F]{40}$.

Say:

Got it: <address>. That's a valid address.

Do: Go to Step 4.

Path B — "Walk me through it"

Say:

1. Install MetaMask (or Rabby, Coinbase Wallet, Frame, Trust Wallet, Phantom, …) from the official site only: https://metamask.io. Make a wallet, save the seed phrase offline, set a password.
2. Add Base as a network. Open https://chainlist.org/chain/8453 → "Connect Wallet" → "Add to MetaMask", then approve it in your wallet.
3. Click "Buy" in your wallet. Pick USDC, network Base, pay with card / Apple Pay / bank. The USDC lands straight in your wallet.
4. Get the private key: account menu → Account details → Show private key → enter password → copy.
5. Add it to your .env (make sure .env is gitignored):

BROWSER_USE_X402_PRIVATE_KEY=<your private key>

6. Send me your wallet's public address (the 0x… one) so I can check it.

Do: Then follow Path A from the address check onward.

Path C — "Make a fresh one"

Do: Generate a wallet. Save the key to .env. Show the address only.

Python:

pip install eth-account

from eth_account import Account
acc = Account.create()
print("Address:", acc.address)
print("Private key:", acc.key.hex())

TypeScript:

npm install viem

import { generatePrivateKey, privateKeyToAccount } from "viem/accounts";
const key = generatePrivateKey();
console.log("Address:", privateKeyToAccount(key).address);
console.log("Private key:", key);

Say:

Made a fresh wallet. Your public address is <address>, and I've saved the private key to .env. Now it needs funds.

Do: Go to Step 4 (funding).

Step 4 — Add funds

If Path A or B (already funded):

Say:

Your wallet's already funded, so we'll skip ahead to the test.

Do: Go to Step 5.

If Path C:

Say:

Two ways to get USDC into your wallet on Base:

• In-wallet Buy button (easiest): click "Buy", pick USDC, set the network to Base, pay with a card. No exchange needed.
• From an exchange: send USDC to <address> and pick "Base" as the network — not Ethereum, which costs $5–$20 in fees.

Add at least $20: that covers the $1 test plus a few real tasks. I'll watch the balance and tell you when it lands.

Do: Check the on-chain balance every 5s with Base's public RPC:

PADDED=$(printf "%064s" "${WALLET_ADDR:2}" | tr ' ' '0')
curl -s https://mainnet.base.org \
  -H "Content-Type: application/json" \
  -d "{\"jsonrpc\":\"2.0\",\"method\":\"eth_call\",\"params\":[{\"to\":\"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913\",\"data\":\"0x70a08231${PADDED}\"},\"latest\"],\"id\":1}"

Read result as a hex number; divide by 1_000_000 (USDC has 6 decimals). Stop once it's $20 or more.

Say:

Funded — I see $ on Base. Next, a quick test.

Step 5 — Test run (~$1)

Do: If SETUP = A, make sure the SDK is installed where you'll run scripts (default Python). If SETUP = B, install it into the project in the project's language — work out the language from the cwd (package.json/tsconfig.json → TypeScript; pyproject.toml/requirements.txt/*.py → Python; ask only if you can't tell):

# Python (needs 3.10+ for the x402 extra)
pip install "browser-use-sdk[x402]"
# TypeScript
npm install browser-use-sdk @x402/fetch @x402/evm viem

Ask: (header: Test run) — question: Ready to test? This spends exactly $1 USDC from your wallet to check payment + run work end to end.

• Use the default task — "Go to example.com and tell me the heading text." (~5 seconds, cheap)
• I'll give you a task — Tell me a short task to run instead.
• Skip the test — Skip the test and go straight to using x402.

Do:

• "I'll give you a task" → Say: What's the task? Keep it short. Wait for it.
• "Skip the test" → go to Step 6.
• Otherwise use the default task.

Do: Run the test. Use the raw x402 client with max_value of $1.50 so it pays $1, not the $5 the SDK uses by default:

import asyncio, os
from decimal import Decimal
from x402 import x402Client
from x402.http.clients import x402HttpxClient
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client
from eth_account import Account

async def main():
    client = x402Client()
    register_exact_evm_client(
        client,
        EthAccountSigner(Account.from_key(os.environ["BROWSER_USE_X402_PRIVATE_KEY"])),
    )
    # max_value caps the spend per request — picks the $1 option over the $5 default.
    async with x402HttpxClient(client, max_value=Decimal("1.5"), timeout=180.0) as http:
        resp = await http.post(
            "https://x402.api.browser-use.com/api/v3/sessions",
            json={"task": "<the task>"},
        )
        print(resp.status_code, resp.json())

asyncio.run(main())

If MODE = B, add the API key header, or the $1 goes to a new wallet project instead of the one being topped up:

async with x402HttpxClient(
    client, max_value=Decimal("1.5"), timeout=180.0,
    headers={"X-Browser-Use-API-Key": os.environ["BROWSER_USE_API_KEY"]},
) as http:
    ...

If the installed x402 lib has no max_value, Say: That x402 version can't force a $1 charge, so the test will cost $5 instead. Want me to go ahead? — wait for a yes before running.

Say:

Paid. On-chain proof: https://basescan.org/address/#tokentxns — look for a USDC transfer out of exactly $1.000000.

Do: Read the balance. If MODE = A (needs browser-use-sdk ≥ 3.8.0; if older, say to run pip install -U "browser-use-sdk[x402]" or skip this):

import asyncio, os
from browser_use_sdk.v3 import get_wallet_balance

async def main():
    bal = await get_wallet_balance(os.environ["BROWSER_USE_X402_PRIVATE_KEY"])
    print(bal['total_credits_usd'])

asyncio.run(main())

If MODE = B, skip get_wallet_balance (it returns 404 — the credits sit in the API key's project, that's normal, don't show it as an error) and read it the normal way:

from browser_use_sdk.v3 import AsyncBrowserUse
client = AsyncBrowserUse(api_key=os.environ["BROWSER_USE_API_KEY"])
acct = await client.billing.account()
print(acct.total_credits_balance_usd)

Say:

Done. Your Browser Use balance is now $ (the test cost about $). Tasks draw from this, and the SDK adds another $5 when it runs out.

Step 6 — Wrap up

If SETUP = A:

Say:

All set. Ask me to run any browser task and I'll run it through the SDK, paid from your wallet.

Do: When they ask for a task, write a throwaway script (in /tmp, or a background job for long ones), run it, report the result, and delete it — don't leave files in their cwd. The SDK reads BROWSER_USE_X402_PRIVATE_KEY and finds the x402 endpoint on its own:

import asyncio, os
from browser_use_sdk.v3 import AsyncBrowserUse

async def main():
    client = AsyncBrowserUse()  # Mode B: AsyncBrowserUse(api_key=os.environ["BROWSER_USE_API_KEY"])
    result = await client.run(task="<the task>")
    print(result.output)

asyncio.run(main())

If SETUP = B:

Say:

All set. Here's the client to use in your code — it reads the key and endpoint from your .env:

Do: Add the client in the project's language and point them at the cloud skill / SDK docs for the rest:

from browser_use_sdk.v3 import AsyncBrowserUse

client = AsyncBrowserUse()                                  # Mode A (accountless)
# client = AsyncBrowserUse(api_key="bu_...")                # Mode B (top up existing account)

(x402 needs the async client — the sync BrowserUse won't run when the x402 env var is set.)

TypeScript equivalents

Both SDKs read BROWSER_USE_X402_PRIVATE_KEY from the env.

Rules

• Follow the script in order. Say the Say blocks word for word.
• Never spend the user's USDC without a clear yes (the Step 5 question is that yes).
• Always offer both ways to add the key: paste it in chat (you write it to .env) or the user adds it themselves. If they paste it, write it straight to .env and never echo it back or store it anywhere else.
• Add .env to .gitignore before saving keys.
• Wallets hold real money. Keep keys out of source control, logs, and screenshots; only add what you can afford to lose if it leaks.

Reference

• x402 user docs: https://docs.browser-use.com/cloud/guides/x402
• Claude Code + Browser Use Cloud: https://docs.browser-use.com/cloud/tutorials/integrations/claude-code
• x402 protocol: https://www.x402.org
• USDC on Base contract: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
• Base RPC: https://mainnet.base.org · Basescan: https://basescan.org