Show HN: Mock PSP API – simulate payments and webhooks

I’ve been tinkering on a side project: a mock PSP (Payment Service Provider) API.

It’s meant for developers who want to:

- test payment workflows without touching Stripe/Adyen/etc. - quickly simulate authorise / decline / capture states - practice handling webhook events in their apps

No signup needed — you can grab an API key in the console and start calling endpoints. Free tier: 100 requests/day.

Live console: https://paylab-ui.vercel.app/ Docs: https://paylab-ui.vercel.app/dashboard/docs

Right now MVP supports:

- POST /payment-intents - POST /payment-intents/:id/payments (supported payment statuses: initiated, authorising, authorised, declined, capturing, expired, captured, capture_failed) - GET /payment-intents/:id - Webhook subscription + delivery history

Would love your feedback!

What’s missing for it to be useful in your dev/test workflow? Should I add another API that you find more useful, or continue developing mock PSP API first?

Thanks!

3 points

・

d_sai

・

2 days ago

2 comments

Dell3420 ・ 2 days ago

Probably something minor, usually people also need to get fraud rate? probably something like that, before transacting (usually score based).

Also probably something else like personal data, will be able to set rule to reject based on country and residence when transacting.

  • d_sai ・ 2 days ago

    Great point! That’s definitely something worth adding to make the API feel more realistic. I’ll look into incorporating a fraud rate simulation along with a simple rule engine in the next version.

    Really appreciate the feedback!