u/fizzl13

My agents pay for APIs on their own now (x402, USDC on Base and Solana). Handy, but I didn't want an agent with an open wallet that can spend everything. So I built a small layer in between: Fizzl Agent Wallet.

What it does:

- Limits per payment and per day, for each agent
- Over the limit, the agent waits and asks you on your phone (Face ID, a push notification or Telegram). No answer means no payment
- A readable receipt for every purchase: what was bought, from whom, for how much, and whether presign-guard found the transaction safe
- The agent keeps its own key. The server only counts, asks and records; it never holds keys or money
- Sign in with a wallet, e-mail or Face ID. It also installs as an app on your phone

You can look around without an account: wallet.fizzl.eu/demo

Free for 1 agent. Want to test Pro (unlimited agents, 90-day receipts, endpoint monitor)? DM me and I'll send you a personal code for 30 days free.

I'm looking for blunt feedback: what's unclear, what's missing, and what would you need before you'd trust something like this with your agent? There's a feedback box inside the wallet, and I read everything.

I run x402 Doctor, a free checker for x402 endpoints. Until today it failed every MCP server, because MCP servers don't return a 402 on their URL: payment happens inside the tool call.
What it checks now for an MCP URL:
1. initialize and tools/list work without payment
2. one unpaid tools/call per paid-looking tool (it skips tools described as free and tools marked destructive; never pays)
3. the payment requirement comes back in the tool result: isError: true, structuredContent, plus JSON text in content[0], which is what @x402/mcp clients read
4. the requirement then gets the normal checks: CAIP-2 network, payTo, amount in atomic units, EIP-712 domain, which wallets can pay
The most common issue in the first servers I tested: answering tools/call with an HTTP 402 instead of a tool result. Fetch-based x402 clients handle that; MCP clients built on @x402/mcp see a transport error.
Small tip for MCP builders: put one valid example call per tool in _meta.examples. Tools that validate input before payment (as they should) otherwise refuse the checker's guessed arguments.
Happy to run it on your server if you drop the URL.

I've been running three pay-per-call x402 APIs for a few weeks: a health checker for x402 endpoints, a pre-sign wallet check (token, approval and EIP-7702 delegate screening before you sign), and a crypto market data service. All accept USDC on Base and Solana, no accounts or API keys. I log every request, and I figured the numbers might be useful to others building here.

**One full day (26 Sep):**

- 4,605 requests across the services
- 29 paid calls, all from my own test wallets
- so: zero organic paid calls so far

**Six hours this morning, market data API only:**

- 433 requests from 118 distinct visitors
- 362 fetched the 402 price quote and left
- 51 hit the free endpoint
- 8 were bad input (`pair=TEST`, `pair=1`)
- 0 paid

**Who's actually calling:**

- **Uptime/price monitors.** One polls two paid endpoints every ~5 minutes and rotated through 32 IPs in 6 hours.
- **Directory verifiers** re-checking each listed route every 30 minutes.
- **Indexers and trust crawlers**: 402explorer, x402-census, ApisTrust, enclave402 and others.
- **Coinbase Bazaar discovery**, which re-checked a new route within hours of its first paid call.
- **MCP auth probes** calling tools that don't exist to see if the server requires auth.
- A handful of humans in a browser, and one developer trying the API with axios.

**What I learned:**

1. **Discovery works, demand is the hard part.** Getting indexed (Bazaar, directories, the MCP registry) was fast. Getting a stranger's agent to pay hasn't happened yet.
2. **Most of the ecosystem right now is infrastructure watching infrastructure.** Judge your service by request count and you're mostly counting other people's monitors.
3. **Your error messages are your docs.** Bots send garbage like `pair=TEST`. A clear 400 ("use e.g. BTC-USDT") is cheaper than a support channel.
4. **Behind a proxy, check you log the real client IP.** Mine logged my host's proxy address for weeks until I set the right number of trusted proxy hops.
5. **Price the decision, not the data.** People don't pay for "BTC is bullish", they pay for "here are 10 trades with entry, stop and targets". So that endpoint is now the most expensive one ($0.50) and the plain market scan dropped to $0.10.
6. **Be honest about what you sell.** I backtested my setups ranker on ~5,000 setups: no edge after fees. So it's sold as a screener, not a strategy.

**Questions for other builders:**

- Has anyone seen organic paid traffic yet? Where did it come from (Bazaar, MCP, a framework plugin, word of mouth)?
- How do you tell a real agent from a monitor in your logs? A user-agent is trivial to fake.
- What price point has converted for you, if anything?

Happy to share the endpoints in the comments if anyone wants to poke at them.