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Sly runs two isolated environments. Your data, keys, and agents in one environment are invisible to the other.

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Test (sandbox) vs. Live

TestLive
Base URLhttps://sandbox.getsly.ai/v1https://api.getsly.ai/v1
API key prefixpk_test_*pk_live_*
Agent token prefixagent_test_*agent_live_*
MoneyFake (Base Sepolia stablecoin, mock cards)Real
KYC/KYBSimulated (instant approval)Real third-party verification
Rate limitsGenerous (1,000 req/min)Standard (100 req/min)
Webhook deliveryDelivered, marked testDelivered, marked live
SettlementInstant mockReal settlement windows
Test and live are fully isolated. Test agents cannot see live accounts. Test transfers do not affect live balances. This includes webhooks, exports, and reports.

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Discovering which environment you’re in

Every response includes an X-Environment header: 
X-Environment: test
And every API key self-identifies by prefix: 
# Test key → sandbox
pk_test_abc123...

# Live key → production
pk_live_xyz789...

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Sandbox conveniences

Only available in test:
  • Instant KYC/KYB — any verify endpoint approves immediately.
  • Faucet funding — agents can call /v1/wallets/:id/fund to self-credit test stablecoin.
  • Skip approval — payments marked requires_approval auto-approve after 2 seconds.
  • Webhook playground — replay any event to your local tunnel via /v1/webhooks/:id/replay.
  • Mock settlement — scheduled transfers execute every 30 seconds instead of the 60-second live cadence.

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Going live

  1. Complete organization KYB via the dashboard: app.getsly.ai → Settings → Compliance.
  2. A Sly operator reviews (typically <24 hours).
  3. Live API keys unlock in the dashboard.
  4. Swap pk_test_* → pk_live_* and sandbox.getsly.ai → api.getsly.ai. Nothing else in your code changes.
Before going live, run the full sandbox testing checklist — especially webhook signature verification. Every production incident we’ve seen at onboarding is either a webhook-signature bug or a rate-limit-retry loop.

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Using both at once

If you run test and live traffic from the same server (common for customer-support tooling that needs to inspect both), route by the caller’s API key prefix rather than by URL. The SDK does this for you: 
import { Sly } from '@sly_ai/sdk';

// Client picks the correct base URL from the key prefix
const sly = new Sly({ apiKey: process.env.SLY_API_KEY });