The API Review: Integrating Airwallex into Custom Apps
Man, let me tell you about diving headfirst into integrating Airwallex’s API into a couple of our custom apps. It was a ride, starting from just poking around their docs to actually getting transactions flowing. I figure I should share the whole messy process, just how it went down.
First Contact: The Documentation Dive
I started where everyone starts: their API documentation. Honestly, the docs were pretty decent. They lay out the basics clearly enough—authentication, endpoints, expected payloads. My first hurdle was just figuring out which specific services we needed. We weren’t just taking payments; we needed to handle multi-currency conversions and refunds smoothly. So I spent the first few hours mapping out which API calls corresponded to our existing application logic. Things like /payment_intents for setting up a transaction and /charges for actually processing it were obvious, but the finer points of their foreign exchange API, /fx, took a bit more digging.
Setting Up the Sandbox Environment
You can’t just hit the live servers, right? So the next step was getting the sandbox set up. This involved creating an Airwallex developer account, getting the necessary API keys (a Client ID and API Key), and making sure I could actually authenticate. This part was straightforward. I used Postman initially just to ensure my authentication headers—which are typically a JWT token you generate—were correctly formatted and accepted. I was hitting their /token endpoint constantly until I got that sweet 200 OK response. Little victories, you know?
- Acquire developer credentials.
- Configure environment variables for sandbox keys.
- Test token generation via Postman.
Coding the Integration: Talking to Airwallex
Once I knew I could talk to them, I moved to the actual app codebase. We primarily use Python for our backend services, so I started writing a dedicated service class to wrap all the Airwallex communication. I didn’t bother using any community SDKs if they had them; I prefer raw HTTP requests to keep control of the data structure.
The first feature I tackled was creating a new payment intent. This involved constructing a JSON payload with the amount, currency, and a description. The tricky part was managing idempotency. Airwallex strongly recommends using an idempotency-key header to prevent accidental duplicate charges. Implementing a reliable mechanism to generate and track those unique keys across our system took a little bit of refactoring on our end.
Dealing with Webhooks and Asynchronous Updates
Payments aren’t instant. You send a request, but the final status—success, failure, or requiring 3D Secure—comes back later, usually through a webhook. This was the next major chunk of work. I had to set up an endpoint on our side that Airwallex could call.
This webhook endpoint needed robust validation. You can’t just trust that the call is from Airwallex. Their solution is signing the webhook payload with a secret key. So I had to write the verification logic to calculate the signature based on the incoming data and compare it with the signature in the header. If it didn’t match, immediate rejection. It was fiddly—getting the exact byte string and hashing algorithm right always is—but crucial for security.
Refining Currency Exchange Logic
Our app deals with multiple currencies, so the FX API was critical. Initially, I just hardcoded the exchange rate calculation using a daily feed, but that’s sloppy. I switched to querying Airwallex’s live FX rates when generating the payment intent. This meant making a quick API call to their /fx/quotes endpoint before initiating the primary charge. This ensures we are using the most current, locked-in rate for the transaction, reducing risk and improving accuracy for the user.
Testing and Going Live
I hammered the sandbox environment with every possible scenario: successful payments, declined cards (using their test card numbers), refunds, partial refunds, and expired quotes. Only once I was confident that our error handling was solid and every webhook was properly processed did we move to production keys. The switch itself was just swapping out the environment variables, which is always nice and clean. The first live transaction? Smooth as butter. Seeing that first real money flow through the system was a great payoff after all the detailed setup work.