A backend developer's career description is where the reviewer checks how you design, operate and improve real systems. List projects under each company, and for every project state your role, the stack you used and what changed in numbers such as latency, error rate or cost. The resume says where you worked; this document shows what you built there.
For: Backend developers with three or more years of experience applying for an experienced-hire role
Start with this example ↗All people, companies and numbers here are fictional. Replace them with your own career.
Hyunwoo Lee
Backend Developer · 7 years
hyunwoo.lee@example.com
Core strengths
• Cut p95 API latency by 70%+ on 3 high-traffic services
• Split a 9-year-old monolith into 5 services without a single outage
• Built on-call runbooks that lowered MTTR from 55 to 18 minutes
• Mentored 4 junior developers through code review and pairing
Career details
Example Commerce Co. · Platform Engineering Senior Backend Developer
2021-04 – Present
Responsibilities Designs and operates the order, payment and settlement APIs for a marketplace with about 2 million monthly users.
Payment Domain Service Split
2023-02 – 2024-01
Role Tech lead · Team Team of 5 · Contribution 50%
Technologies Kotlin · Spring Boot · Kafka · PostgreSQL
• Extracted payment and refund logic from the monolith into 2 services with 0 downtime.
• Reduced payment-related deploy time from 40 minutes to 8 by separating pipelines.
• Introduced idempotency keys that cut duplicate charges by 98%.
Order API Performance Overhaul
2022-03 – 2022-10
Role Backend developer · Team Team of 3 · Contribution 60%
Technologies Java · Redis · MySQL
• Rewrote 3 N+1 queries and added a read-through cache for order lookups.
• Lowered p95 latency from 820 ms to 190 ms at 1,200 requests per second.
• Cut database CPU usage during peak sales events by 45%.
Observability and On-call Setup
2021-07 – 2021-12
Role Owner · Team Team of 2 · Contribution Lead
Technologies Prometheus · Grafana · PagerDuty
• Defined alerts for 14 core endpoints and wrote 6 incident runbooks.
• Lowered mean time to recovery from 55 minutes to 18 within 2 quarters.
Example Logistics Inc. · Delivery Systems Team Backend Developer
2018-03 – 2021-03
Responsibilities Built APIs for dispatch, driver tracking and delivery status used by partner shippers.
Real-time Delivery Tracking API
2019-05 – 2020-06
Role Backend developer · Team Team of 4 · Contribution 35%
Technologies Node.js · MongoDB · WebSocket · AWS
• Built a location ingestion pipeline handling 3,000 driver updates per minute.
• Reduced status-inquiry calls to the support center by 30%.
• Onboarded 12 partner shippers, including Company A, to the public API.
Reason for leaving Moved to a larger-scale platform role
Skills
Languages & frameworks Kotlin · Java · Spring Boot · Node.js
Data & messaging PostgreSQL · MySQL · Redis · Kafka
Three keys to a Backend Developer career description
01
Organize by company, then by project
Reviewers read a career description to find the two or three projects closest to the role they are hiring for. Group projects under each employer, most recent first, and give each project its own period, role, team size and stack so it can be read on its own without the rest of the page.
02
Separate your share from the team's result
Backend work is almost always done in teams, so state the team size and your contribution explicitly. A line such as 'Team of 6, contribution 40%' followed by the modules you owned lets the interviewer ask precise questions instead of guessing what part was yours.
03
Quantify with operational metrics
Response time, throughput, error rate, deployment frequency and infrastructure cost are the numbers backend reviewers trust. Give a before and after value, and when the real figure is confidential, write it as a ratio, for example 'p95 latency cut by 60%', rather than leaving the line vague.
Rewrite result lines like this
BeforeWorked on improving the performance of the order API.
AfterAdded a Redis read-through cache and rewrote 3 N+1 queries in the order API, cutting p95 latency from 820 ms to 190 ms at 1,200 requests per second.
The fix, the scale and the before-and-after numbers show both the technical judgment and the size of the impact.
BeforeWe migrated the monolith to microservices.
AfterLed the extraction of the payment domain from the monolith into 2 services (team of 5, contribution 50%), reducing payment-related deploy time from 40 minutes to 8.
Replacing 'we' with your role and contribution makes the scope of your own work clear, while the team size keeps it honest.
BeforeResponsible for server monitoring and incident response.
AfterBuilt Prometheus and Grafana alerts for 14 core endpoints and wrote 6 runbooks, lowering mean time to recovery from 55 minutes to 18.
A duty description says what was assigned; a result line says what improved because you were there.
Common mistakes
Listing every technology ever touched instead of the 2 to 5 used in each project
Writing 'we built' so the reader cannot tell which modules were yours
Describing performance work without a before-and-after number or ratio
Including internal service names or real traffic figures that are confidential
Frequently asked questions
How many projects should I include per company?
Two or three for your most recent employer and one or two for earlier ones is usually enough. Choose the projects closest to the posting, and move smaller maintenance work into a single summary line rather than giving each its own block.
What if I cannot share real traffic or revenue numbers?
Use ratios and relative changes such as '3x throughput' or '35% lower cost', or describe scale in ranges. Refer to clients as 'Company A' when the relationship is confidential. The reviewer needs the size of the change, not the internal figure.
Should I include a GitHub link or architecture diagram?
A link to a public repository or technical blog post is welcome if it relates to the projects listed. Keep diagrams out of the document itself; they take space and rarely print well. Mention that you can walk through the architecture in the interview instead.
Build your career description from this example
The button opens a career description filled with this example in the editor. You need to sign in, and you can change content and design freely. The editor's check panel flags result lines without numbers and the page count.