I'm exploring an idea for a developer-focused SaaS: A unified UAT environment for payment gateways — essentially a sandbox simulator that lets developers integrate payments without creating multiple sandbox accounts or dealing with inconsistent/mock behaviors across gateways.
The Problem
If you’ve ever integrated payments, you know:
Stripe has excellent test tooling
Razorpay is decent
Paytm/PayU/etc vary a lot
Many banks don’t have predictable UAT behavior
Webhooks arrive differently, some delayed, some flaky
Testing disputes/refunds/settlements is nearly impossible
For dev teams building complex flows, they end up writing internal mocks, maintaining them, and still missing edge cases.
The Idea (SaaS)
A unified Payment Sandbox Simulator that:
Mock APIs for multiple gateways
Stripe
Razorpay
Paytm
PayU
Cashfree
Worldline
Visa/Mastercard tokenization mock
UPI PSP simulators
Simulate real-world scenarios
Captures
Refunds
Partial refunds
Chargebacks
Disputes
Settlement delays
Failed payouts
KYC verification
Randomized webhook delays/skips
Network downtime simulation
3-D Secure / OTP mock pages
UPI timeouts / pending states
Hosted dashboards
View mock transactions
Trigger lifecycle events (manually or timed)
Trigger webhooks again
Create custom gateway profiles
Define “rules” to simulate: failure %, latency, webhook disorder, retries
For engineering teams
Private UAT environment in one URL
No more creating 10 sandbox accounts
CI-friendly “headless payment” flows
Add Mock PG in local → swap to real PG in staging
Automatic contract testing
Pricing thought
Free Tier → 100 test transactions/mo $29/mo → small teams $99/mo → startups $499/mo → enterprise / white-label
Ask to HN
Would you use this? What’s missing? Would payments teams trust a 3rd-party simulator? Which gateways or scenarios matter most?
Happy to answer questions
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