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Runnable API Integrations
For Developers.

Build, test, and verify real API integrations with production-like environments, stateful APIs, and webhook flows.

Run Resend workflow
StripeTwilioGitHubOpenAIResendClerkPolar

How it works

Connect.
Run.
Ship.

01 —

Connect

Add the FetchSandbox MCP to your IDE in 30 seconds. Works with Cursor, Claude Code, Cline, Windsurf, and more.

02 —

Run

Pick an API. Your agent runs real workflows against a live sandbox — requests, state changes, webhooks. No keys, no setup.

03 —

Ship

Generated code is grounded in verified API contracts. Drop it into your repo and ship with confidence.

Proof, not promises

Test Webhooks, Retries,
And State Changes End-To-End.

A real Stripe accept_payment run — live animation on the left, the trace it produces on the right. Every state change and webhook is exercised exactly the way production does it.

Runnable integrationlive sandbox
POST /v1/charges…
customer.balance
charge.succeeded
verify final state

running workflow…

Stripe · accept_paymentpassed
POST /v1/customers200 · cus_NjxYy3kQ
POST /v1/payment_intents200 · pi_3NjxYy3kQ
customer.balance$0.00 → $20.00
webhook · payment_intent.succeededdelivered
verify final statepassed ✓
5 / 5 reconciliation fields verified

Why FetchSandbox

Most Integration Bugs Happen
After The 200 OK.

Postman
Mock servers
Static docs
FetchSandbox
Real API requests
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Stateful workflows (calls build on each other)
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Real webhooks delivered
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Verifies the API contract end-to-end
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Generates code grounded in proof
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