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Fiverr Pro
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$
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I will integrate wechat pay API v3 into your existing backend
Haohce
About this gig
You have a backend and a merchant entity. You need WeChat Pay wired in.
The endpoints are documented. Production failures usually come from trust and ordering: the client's success callback is not proof of payment, a notification may arrive more than once or before the client returns, and a valid signature still does not prove the amount matches the order.
I work on that layer. Prepay parameters, callback signature verification, merchant and amount checks before any state change, idempotent paid transition, order query and close, refunds where your permissions allow.
You keep your merchant ID, API v3 key, certificates and private keys. Do not paste secrets into an order requirement or ordinary chat. For implementation work, use a buyer-controlled test environment and rotate any temporary credentials after delivery.
I will not claim a merchant qualification or category restriction can be bypassed. Where the platform is the blocker, I will tell you which requirement it is.
Basic is a review: your stack, your merchant readiness, a written integration checklist and the state machine I would build. No keys, no production changes.
Written-first and asynchronous.
Get to know Haohce
Haohce
China side QA and WeChat Mini Program developer
- FromChina
- Member sinceOct 2025
- Avg. response time2 hours
Languages
Chinese, English
I am a developer based in mainland China. I test websites, apps and payment flows that may behave differently for users in China, using real devices here. You receive screen recordings, screenshots and a written report with steps to reproduce.
I also build and fix WeChat Mini Programs, CloudBase functions and WeChat Pay API v3 backends. I separate AppID permissions, legal domains, HTTPS, development builds, trial versions, releases and callback verification, so you know the exact state of the work.
I work written-first and asynchronously, with clear scope and evidence for each result.
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FAQ
Do you need my API v3 key and certificates?
Not for Basic. For implementation work I need access to a test configuration, and we agree the channel before anything is sent. Never paste keys or private keys into chat. You keep ownership throughout.
Can you get me a merchant account?
No. The merchant account belongs to a legal entity and requires that entity's own materials and verification. I can tell you what the application will ask for, but I cannot hold or obtain it for you, and I do not review your corporate or legal documents.
Will the integration be tested with a real payment?
Only where your merchant conditions allow it and you agree to it. I report that step separately because a test-environment pass is not the same as a settled real charge.
Why is the client-side success callback not enough?
Because it only proves the payment UI returned. The authoritative event is the signed asynchronous notification from the provider, checked for merchant identity and amount, and applied idempotently. Treating the client event as payment is how orders get marked paid that were never charged.
What about refunds?
Refund is a separate permission from payment on the merchant side, and having one does not mean having the other. If refunds are in scope we confirm the permission exists first.
Which backends do you work with?
Node.js primarily; also Python (FastAPI) and comparable server stacks. Tell me your stack and I will say honestly whether it is a fit.
What if my merchant application is still pending?
Then Basic is the right package. You get the architecture, technical prerequisites and state-machine checklist, ready to implement when the account clears. I do not review your legal or corporate application materials.
Can we do a call?
Written-first and asynchronous. For payment work a written record of exactly what was agreed and what was verified is worth more than a call, for both of us.
