Overview
What this challenge is about.
Add Idempotency Keys to a Payment Webhook System. Advanced challenge in code. Writing production code that solves real engineering problems, earn a blockchai...
The Brief
What you'll do, and what you'll demonstrate.
Design and implement an end-to-end idempotency-key mechanism for the merchant webhook system that proves zero duplicates under realistic retry storms.
This is not a coding exercise. It is the work a software engineer does between a Jira ticket and a merged PR. That distinction matters to every hiring manager who has seen candidates solve LeetCode problems and none who have shipped production code under real constraints.
When you finish, you will have something most graduates do not: a real-world deliverable, verified by Ewance, that you can show to a hiring manager and say "I did this. Here is the proof."
Earning criteria — what you'll demonstrate
- Design an end-to-end idempotency scheme for a payment system
- Implement at-most-once semantics with Postgres-backed storage
- Validate idempotency under chaos-test conditions
- Communicate a public-API contract change to external partners
Program Fit
Where this fits in your program.
Sharpens the same skills your degree expects you to demonstrate.
Aligned coursework coming soon.
Skills
Skills you'll demonstrate.
Each one shows up on your verified credential.
- Api Design
Design RESTful and GraphQL APIs that are intuitive, consistent, and well-documented.
- Idempotency
Apply idempotency to solve real industry problems and demonstrate production-level capability.
- Webhooks
Apply webhooks to solve real industry problems and demonstrate production-level capability.
- Go
Apply go to solve real industry problems and demonstrate production-level capability.
- Postgresql
Apply postgresql to solve real industry problems and demonstrate production-level capability.
- Documentation
Apply documentation to solve real industry problems and demonstrate production-level capability.
Careers
Career paths this challenge builds toward
Completing this challenge demonstrates skills that transfer directly to these roles: