Runnable API integrationsfor developer and agents

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Runnable API integrationsfor developer and agents

The memory graph that lets your AI ship integrations without burning real APIs.

• Pre-configured APIs ready to use
• Works with Cursor, Claude, Codex CLI & more
• Test webhooks, auth, requests, and responses easily
• Go from idea → working integration in minutes

Start Testing APIsBrowse API Catalog

Pre-built support for Stripe, GitHub, OpenAI, Paddle, Twilio and more

Build and test API integrations without leaving your AI coding assistant.

Pre-configured integrations available today

StripeTwilioResendClerkPPrivyAAgentMailSSurgeKKulipaWWorkOSStripeTwilioResendClerkPPrivyAAgentMailSSurgeKKulipaWWorkOS

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Most API tests stop at successful responses.

FetchSandbox verifies webhook delivery, workflow state,

Your agent stops shipping integrations that “work” in tests but break in production. Every workflow run includes the spec of what success looks like — terminal state, required webhook events, invariants — verified end-to-end.

\>\_

Traditional Integration Testing

$ curl -X POST https://api.example.com/charge \\

\-d '{"amount":1000}'

200 OK

Response time: 142ms

✗ No webhook delivery confirmation

✗ Agent infers: did it actually work?

✗ Drift between test setup and prod

✗ Burns real API quota during dev

✗ No visibility into workflow state

Dev@08 \~ %

Using FetchSandbox

\> ./fetchsandbox <your bug or task>

brain.matched correct bug pattern

scenario.run reproduces deterministically

fix.applied from brain's fix\_pattern

audit.surfaced check\_for items as checklist

receipt.url public, replayable proof

✓ Brain encodes spec-specific failure modes

✓ Reproduces bugs without touching real API

✓ Receipt URLs you can paste in PRs and Slack

✓ Zero real-API quota burned

✓ Same prompt = same outcome, every time

Dev@08 \~ %

Api Request

Webhook Sent

Validation

State Verified

Production Safe

Build and test APIs without complex setup

Connect your tools, test real API workflows, and ship integrations with confidence.

Connect

Add FetchSandbox to your IDE and start testing APIs in minutes. Works with Cursor, VS Code, Claude Code, Windsurf, and more.

Run

Simulate real API behavior like webhooks, retries, failed requests, and async events. No mock servers. No complicated setup.

Ship

Generate reliable integrations using real API responses and verified workflows. Ship faster with fewer production issues.

Most API tests stop at successful responses.

Run complete workflow simulations with live events, edge cases, and failure states in one sandbox.

Start Testing APIs

FetchSandbox · Watch a real workflow run, end to end

Powering the Next Generation of API Development

Used to test webhooks, retries, async workflows, and production-ready integrations.

1,500+

Monthly Active Users

1,600+

MCP Installs

60+

APIs live

Frequently asked questions

Everything you need to know about testing APIs, simulating workflows, and shipping reliable integrations with FetchSandbox.

What exactly does FetchSandbox do (for developers)?

Is there a free tier? How many requests?

Can I simulate 4xx/5xx errors, rate limiting, or delays?

Does it have a CLI or GitHub Action?

Is my data secure? SOC2? Self-hosted?

How is this different from Postman mocks or WireMock?

From API request to production ready integration.

Build, test, and validate API integrations in realistic environments before deployment. Catch failures early, reduce debugging time, and ship with confidence.

Try FetchSandboxUpload OpenAPI spec