At work 2023-now
Backend services
Designed and built; set the standards
Small services, each owning one business area, such as rules, payments, offers or login. All share one framework, so one fix reaches all.
01 The problem
The backend covers many business areas, such as rules, pricing, offers and login. Each area is its own service. Each service solved the same basics, like login checks, databases and caching, in its own way.
02 What I built
- 01
Shared Python framework
One versioned library that every service is built on. It has tested parts, such as a lock that a late worker cannot break and a rate limiter that stays fair across many servers. Its shared database layer also has a text search that combines exact word ranking with typo-tolerant matching.
- 02
Admin app, moved in steps
A small admin backend needed to change faster, so it was moved into separate services one area at a time, with no big rewrite, until only a thin gateway was left. This fit that app and that team; it is not a rule for every team.
- 03
Business rule engine
Customer staff write "if this, then that" rules, and the system applies each rule to every matching item at once. One rule runs as a database or search query and is explained back in plain English.
- 04
Pricing system
A payment service shows correct monthly payment plans on customer websites, also in reverse (from a monthly budget to a price). The data collectors that feed it find hidden rates from an outside calculator's public payments with exact math, and save a value only when exactly one answer fits.
- 05
Offers engine
Picks which sales offers each customer site shows and where, by walking ordered rules. A failed stock count freezes the offer state instead of deleting, and a person's locked edits survive data imports.
- 06
API gateway
The front door for all backend APIs: it checks every login token once, passes a trusted identity to the services, and was hardened after security audits.
- 07
Login service
One login and single sign-on for every app, where reuse of an old refresh token cancels the whole token family, so a stolen token stops working.
03 How it works
- 01Every service is built on one shared, versioned framework.
- 02An API gateway checks each login once, at the front door.
- 03It passes a trusted identity on to the right service.
- 04Each service runs its own business area.
04 Result
- One fix in the shared framework reaches every service.
- Customer staff write simple rules that are explained back in plain English.
- Customer websites show correct monthly payment plans, also from a budget.
- A stolen login token stops working.
Stack
- Python
- FastAPI
- PostgreSQL
- SQLAlchemy
- Redis
- Celery
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