Slide 1
You told your coding agent to wire up Stripe. The mock returned two hundred OK, then production threw a four-oh-four on the next call. Meet FetchSandbox.
An ordinary mock has no memory.
Here's why. An ordinary mock keeps no memory between calls, so the second one comes back a four-oh-four. FetchSandbox is a stateful fake of fifty-plus real APIs that actually remembers.
The whole lifecycle, not one green check.
Stateful means four things a plain mock can't do. What you POST is there on the next GET. Resources move through real states. Webhooks actually fire. And IDs chain. The whole lifecycle, not one green check.
One line in your MCP config.
{
"mcpServers": {
"fetchsandbox": {
"command": "npx",
"args": ["-y", "fetchsandbox-mcp"]
}
}
}It installs as an MCP server in one line, no keys, no accounts, into Cursor, Claude Code, and Codex. So the agent that just wrote your integration can test it itself, headless.
Every run is a replayable receipt.
And here's the clever part. Every run hands you a replayable receipt link . Drop it in a pull request or Slack, and anyone replays the exact bug, no real API, no burned quota. It even fakes the failures, retries, duplicate webhooks, auth errors.
Product, not a feature.
So, product or feature? Definitely a product, a real engine with fifty-plus pre-built APIs. But two things worth knowing. Stateful mocking isn't brand new, and it's a modeled fake, so it mirrors behavior and state, not every vendor quirk. Its real edge is being MCP-native, out of the box.
Free tier, five dollars a month after.
Pricing is plain, free tier, five dollars a month after. It's built by Raj Nagulapalle, who spent years wiring API integrations. If your AI writes integrations, this catches the bug before production does.
