How to Test Invincible Pay API Integrations Before Going Live
Testing a payment integration against real money movement is not something any developer wants to do by accident. Before you connect Invincible Pay's API to a live product, you need a safe way to confirm your authentication, transaction flows, and webhook handling all work as expected. This guide walks through how to structure that testing process, from getting credentials to simulating edge cases, so your integration is solid before it touches a real e-Transfer.
Why Test Before You Go Live
A payment integration has more failure points than most APIs: signed requests, asynchronous webhook events, multiple transaction states (pending, completed, failed, reversed), and money that has to end up in the right place every time. Skipping structured testing means finding these problems in production, with real customer funds involved. A deliberate testing pass, ideally with a non-production credential set >> CONFIRM WITH ENG: does InvinciblePay offer sandbox/test-mode API keys, or is testing done against production with small real amounts?, catches integration bugs before your customers do.
What You'll Need Before You Start
An Invincible Wallet account with API access enabled
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An API key and secret, generated from your dashboard
A way to receive and inspect webhook events (a tool like ngrok or a logging endpoint works well during development)
A Canadian bank account or e-Transfer-capable account to test with, if you're not using sandbox credentials
Setting Up Authentication Correctly First
Every request to the Invincible Pay API is signed, not just authenticated with a static key. This is one of the most common places integrations break during testing, so it's worth verifying in isolation before you test any actual payment flows.
The API uses HMAC-SHA256 signatures. Your request is signed using, in order: the current Unix timestamp in milliseconds, the HTTP method in uppercase, the request path (excluding query string), the query string if one exists (including the ?), and the request body. That signed value goes in an X-Signature header alongside an X-Timestamp header, with your API key passed as a bearer token in the Authorization header.
A few things worth testing explicitly here:
Confirm your signature matches when the request body is empty (some HTTP libraries send
nullversus an empty string, which breaks the signature)Confirm your JSON serialization doesn't change key order or formatting between signing and sending, since the signed body must exactly match what's transmitted
Test what happens with a clock that's out of sync, since the timestamp is part of the signed payload
Once you can hit the /health endpoint and get a clean response, and /v1/accounts/me returns your account context correctly, you know your authentication layer is solid and you can move on to testing actual transaction flows.
Testing Pay-In Flows
Pay-ins are how money enters a wallet through your integration, whether that's an e-Transfer, a payment link, or a checkout session. When testing pay-ins, work through each of these scenarios rather than just the happy path:
A successful transaction that completes end to end
A transaction that's initiated but never completed by the payer (an abandoned e-Transfer or an expired payment link)
A transaction that fails validation on your side before it's even sent (bad amount formatting, missing required fields)
A duplicate request, to confirm your integration handles retries without double-charging
Testing Payouts
Payouts, whether e-Transfer, EFT, or wire, need the same rigor in reverse. Since payouts move money out, an integration bug here is more consequential than one on the pay-in side. Test for:
A payout to a valid, verified beneficiary
A payout to a beneficiary with missing or invalid details, to confirm your error handling catches it before the request is sent
What your integration does if a payout is created but the confirmation response is delayed or lost, since you need to avoid firing a duplicate payout in that scenario
Testing Webhooks
Most of what happens after a transaction is created, like a payment completing, failing, or reversing, is communicated asynchronously through webhooks rather than the original API response. This means your webhook handler is just as important to test as your request-sending code.
At minimum, verify that your handler:
Correctly validates the authenticity of incoming webhook events rather than trusting any request that hits the endpoint
Handles events arriving out of order (a completion event arriving before a pending event, for example)
Is idempotent, so receiving the same event twice doesn't create duplicate records on your end
Has a retry or dead-letter strategy for events your endpoint fails to process the first time
Testing Error Handling
The API returns structured errors with standard HTTP status codes, so your integration should be built to parse and act on those rather than treating every non-200 response the same way. Before going live, confirm your integration correctly handles:
Authentication failures (expired or invalid keys, bad signatures)
Validation errors (malformed requests, missing required fields)
Rate limiting, if your integration sends requests in bulk (payroll runs or batch payouts, for example)
Downstream failures, like a bank rejecting a transfer after it was accepted by the API
A Pre-Launch Checklist
Before you point your integration at production, it's worth running through a short checklist:
Authentication and signing work correctly, including edge cases like empty bodies and clock drift
Pay-in flows are tested for success, failure, and abandonment
Payout flows are tested for success and for invalid beneficiary data
Webhook handling is idempotent and validates event authenticity
Error responses are parsed and handled explicitly, not treated as a generic failure
Your team has a plan for monitoring transactions once live, not just for the integration test phase
Invincible Pay's API gives you full programmatic access to e-Transfers, EFT, wire payouts, payment links, and checkout from a single wallet, so most integrations touch more than one of these flows. Testing each one on its own, rather than only testing your primary use case, is what prevents a working demo from becoming a production incident.
FAQ
How do I get API credentials to start testing? API keys and secrets are generated from your Invincible Wallet dashboard. >> CONFIRM WITH ENG: any additional steps for test credentials specifically.
What's the best way to test webhooks locally during development? A tunneling tool like ngrok lets you expose a local development server to receive webhook events while you build, so you can inspect and debug payloads before deploying your handler.
How do I know my request signature is correct? Start with a simple authenticated request, like /v1/accounts/me, and confirm you get a valid response before testing more complex, higher-stakes endpoints. If the signature is wrong, you'll get an authentication error rather than a business-logic error, which makes it easy to isolate.
Get Started
Ready to build on Invincible Pay's API? Open your Invincible Wallet to get access to your dashboard and API keys, or talk to our fintech team about white-label and custom payment flows.
