Backend developer

What does a backend developer do?

A backend developer builds the server-side part of a software product.

This is the code that stores data, applies business rules and answers requests from apps and websites.

In Singapore, backend developers work in banks, government agencies, startups, logistics firms and technology companies. They usually sit in a product or engineering team, reporting to a tech lead or engineering manager.

You work daily with frontend and mobile developers, product managers, QA engineers and DevOps or platform engineers. You also talk to business teams to understand what a feature must do.

What the work involves

• Write and review server-side code and APIs for new features.
• Write unit tests and fix defects found in testing or in production.
• Talk to product managers and business users to turn requests into technical specifications.
• Check new and changed code for security risks and follow secure-coding standards.
• Prepare software releases and check that they are ready to go live.
• Watch dashboards and logs, and respond when a service slows down or fails.

Pay in Singapore

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Skills a backend developer needs

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Backend developer job description

A Singapore employer hiring a backend developer wants someone to build and maintain the server-side systems, APIs and data stores behind its products.

You join a product or engineering team, ship features in sprints and work closely with frontend, QA and DevOps colleagues.

Responsibilities

• Design and build server-side services and APIs that are reliable and easy to maintain.
• Turn business needs into written technical requirements and specifications.
• Design database schemas and write efficient queries.
• Write unit and integration tests for the code you deliver.
• Follow secure-coding standards and help identify the attack surface of new and changed systems.
• Support threat modelling sessions and fix vulnerabilities found in scans or reviews.
• Run builds, verify releases and take part in release readiness reviews.
• Integrate your services with other internal systems and third-party providers.
• Monitor services in production, investigate incidents and write up the cause.
• Review teammates' code and share knowledge with junior developers.

Requirements

• A diploma or degree in computer science, information technology or a related field, or equivalent practical experience.
• Typically 2 to 5 years of experience for a mid-level role. Entry roles accept graduates with internships or strong projects.
• Working skill in at least one backend language such as Python, Java, Node.js or Go.
• Experience with a relational database such as PostgreSQL, and with caching tools such as Redis.
• Familiarity with Git, Docker, CI/CD pipelines and one major cloud platform (AWS, Azure or GCP).

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Backend developer career path

Most backend developers start by delivering features under guidance, then take on design decisions and mentoring.

After that, the path splits into deeper technical work or people management.

1. Junior backend developer

   Entry

   You build smaller features and fix bugs under guidance, and learn the team's code, tools and release process.

2. Backend developer

   Mid · SkillsFuture title

   You build server-side systems and APIs, write tests, follow secure-coding standards and support releases with little supervision.

3. Senior backend developer

   Senior · SkillsFuture title

   You lead the design of larger systems, set coding standards, guide quality and security practices and mentor other developers.

4. Tech lead or principal engineer

   Lead

   You set technical direction across several teams, decide on architecture and work with business leaders on priorities.

Steps marked "SkillsFuture title" follow the career pathway in the SkillsFuture Skills Framework. The others are titles commonly used in Singapore.

Related jobs and their pay

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Backend developer interview questions

We wrote these questions from the skills this job needs. They are not an official question bank.

1. Design a REST API for placing and cancelling food delivery orders. What endpoints, status codes and error responses would you use?

   What a good answer covers

   • Uses clear resource names and the right HTTP methods.
   • Returns suitable status codes such as 201, 400, 404 and 409.
   • Validates input and gives consistent error messages.
   • Mentions versioning and pagination for list endpoints.
   • Explains authentication and who may cancel an order.

2. A mobile app retries a payment request after a timeout. How do you stop the customer being charged twice?

   What a good answer covers

   • Explains idempotency keys sent by the client.
   • Stores the key and result so a repeat request returns the same response.
   • Uses a database transaction or unique constraint to block duplicates.
   • Handles the case where the payment provider's answer is unknown.
   • Logs the request so support can trace it.

3. A PostgreSQL query that ran in milliseconds now takes several seconds. How do you find the cause?

   What a good answer covers

   • Runs EXPLAIN ANALYZE and reads the query plan.
   • Checks for missing or unused indexes and full table scans.
   • Looks at table growth, outdated statistics and locking.
   • Rewrites the query or adds an index, then measures again.
   • Considers whether the load is better handled with caching or a read replica.

4. When would you add Redis in front of a database, and how do you keep cached data from going stale?

   What a good answer covers

   • Names read-heavy, slow or repeated queries as good cache candidates.
   • Describes time-to-live settings and explicit invalidation on writes.
   • Explains cache-aside and what happens on a cache miss.
   • Mentions risks such as a stampede when many keys expire together.
   • Notes that some data, such as account balances, needs care before it is cached.

5. Your team has one large application. Would you split it into microservices? What would you consider first?

   What a good answer covers

   • Starts with the problem being solved, not the trend.
   • Weighs team size, deployment needs and clear service boundaries.
   • Names the costs: network calls, data consistency, testing and monitoring.
   • Suggests splitting out one well-defined part first.
   • Explains how services communicate and handle failures.

6. Explain how injection and broken access control happen in a web backend, and how you prevent them in your code.

   What a good answer covers

   • Uses parameterised queries instead of building SQL from user input.
   • Checks permissions on the server for every request, not only in the interface.
   • Validates and encodes input and output.
   • Keeps secrets out of source code.
   • Mentions code review, dependency scanning and security testing.

7. A Kafka consumer is falling behind. How do you find out why and what do you change?

   What a good answer covers

   • Checks consumer lag per partition.
   • Looks at slow processing, database calls and failed messages.
   • Considers adding consumers up to the partition count.
   • Explains retries, dead-letter topics and handling duplicate messages.
   • Discusses delivery guarantees such as at-least-once.

8. You are given a Python service to run in Docker. How do you build a small, safe image and run it in different environments?

   What a good answer covers

   • Uses a slim base image and a multi-stage build where it helps.
   • Runs the process as a non-root user.
   • Keeps configuration and secrets in environment variables or a secrets manager, outside the image.
   • Pins dependency versions and scans the image.
   • Adds a health check so the platform can restart the container.

1. After a release, response times double and error alerts fire. Walk us through the first hour.

   What a good answer covers

   • Checks dashboards and logs to confirm scope and start time.
   • Compares the timing with the release and decides whether to roll back.
   • Tells stakeholders what is known and gives updates.
   • Finds the cause using traces, slow queries or resource use.
   • Writes a post-incident review with follow-up actions.

2. Design a service that sends booking confirmations to several hundred thousand users when a popular ticket sale opens.

   What a good answer covers

   • Asks about expected load, delivery time and what must not be lost.
   • Places a queue or stream between booking and notification.
   • Plans for retries, duplicate prevention and rate limits from email or SMS providers.
   • Scales workers separately from the booking service.
   • Describes monitoring and what happens when a provider is down.

3. A product manager wants a feature live in two days, but you spot a security weakness in the design. What do you do?

   What a good answer covers

   • Explains the risk and its likely impact without jargon.
   • Offers options, such as a smaller release or a quick fix.
   • Raises the issue openly and agrees any delay of the fix.
   • Involves the security team or tech lead when the risk is serious.
   • Records the decision and any follow-up work.

1. Tell us about a bug you introduced that reached production. What happened and what changed afterwards?

   What a good answer covers

   • Describes the issue honestly and owns their part.
   • Explains how it was found and fixed.
   • Names the test, alert or process added to prevent a repeat.
   • Shows how the team was informed.

2. Describe a code review where you disagreed with a teammate on the design. How did it end?

   What a good answer covers

   • Focuses on technical reasons.
   • Listens to the other view and asks questions.
   • Uses data, a small prototype or team standards to decide.
   • Accepts the outcome and moves on.

3. How do you use AI coding tools such as Copilot or Cursor in your work, and how do you check what they produce?

   What a good answer covers

   • Gives real examples, such as drafting tests or boilerplate.
   • Reads and understands every line before committing it.
   • Runs tests and checks for security issues and wrong assumptions.
   • Keeps secrets and customer data out of the tools.
   • Follows the employer's policy on approved tools.

1. Your service stores customers' NRIC numbers, phone numbers and addresses. How do you build it with the Personal Data Protection Act (PDPA) in mind?

   What a good answer covers

   • Collects only the data the service needs, for a stated purpose.
   • Checks whether NRIC collection is allowed and uses other identifiers where possible.
   • Encrypts data in transit and at rest and limits access by role.
   • Sets retention rules and deletes data that is no longer needed.
   • Supports access and correction requests and has a plan for reporting data breaches.

Common questions about a backend developer job

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