What Language Is Amazon Written In?
Amazon is not written in one language. Java carries most of the backend, with C++ and Rust underneath and Python, Go and TypeScript around them.
Amazon is not a single program. It is thousands of small services that talk over the network. Each team picks the language that suits its service, inside a short approved list.
That design has a name. It is a service oriented architecture, meaning each part is deployed and scaled on its own. So the honest answer is a list, not one word.
The Main Languages and Where They Are Used
| Language | Where Amazon uses it |
|---|---|
| Java | Most backend services, retail order flow, many AWS control planes |
| C++ | Low latency and high throughput parts, some AWS data planes |
| Rust | Newer systems work, including the Firecracker virtual machine monitor |
| Python | Automation, data pipelines, machine learning, internal tools |
| JavaScript and TypeScript | The website front end and Node.js services |
| Go | Some microservices and internal infrastructure tools |
| Kotlin and Swift | The Android and iOS shopping apps |
Java is the safest single answer if someone asks you to name one. It is the default for new backend services on many teams.
What AWS Is Written In
AWS is built by Amazon, so it shares the same language set. The split inside AWS follows performance needs.
The control plane is the part that handles your API calls, such as creating a server. Much of it is Java.
The data plane is the part that moves your actual traffic and data. That is where C++ and Rust appear, because every microsecond is repeated billions of times.
Rust is the clearest public example. Amazon released Firecracker, the virtual machine monitor behind AWS Lambda and Fargate, as open source, and it is written in Rust. Amazon has also said publicly that it uses Rust for parts of S3 and other services.
Note that AWS itself is not a programming language. It is a set of cloud services you call from any language through an SDK.
How Amazon's Language Mix Changed
Amazon's website did not start on Java. The early store was built largely in C and C++ with Perl on top.
As traffic grew, the single large application was split into services. Java became the common choice for those services because of its libraries and its stable performance under load.
Rust arrived much later and is still a smaller share. It is chosen when a team wants C++ speed with stronger memory safety.
Amazon does not publish a count of its lines of code. Any total you see online is a guess.
Which Language You Should Use in an Amazon Interview
This is the part that matters if you are preparing.
Amazon lets you choose your own language in a coding interview. Java, Python, C++, C#, JavaScript, Go and Ruby are all commonly accepted.
Your choice does not raise or lower your score. Fluency does. Pick the language you can write in without looking things up.
Python is popular because it is short to type on a shared screen. Java is popular because many Amazon interviewers read it daily. Either is fine.
One exception is worth knowing. If the job description names a language, expect some questions in that language.
| Question | Short answer |
|---|---|
| Does Amazon use Java? | Yes, heavily, especially on backend services |
| Does Amazon use Python? | Yes, for data, machine learning, scripting and tools |
| Does Amazon use Go? | Yes, but less than Java or Python |
| Does Amazon use Rust? | Yes, in systems and AWS infrastructure work |
| Can I interview in any language? | Yes, any mainstream language you know well |
For more detail see what coding language Amazon uses and which programming language is best for getting a job at Amazon.
How to Prepare
- Choose one language and stay with it. Switching mid preparation costs weeks. Learn its standard library well, especially maps, sets, heaps and sorting.
- Practice patterns, not the language. Amazon repeats a small set of problem shapes. Grokking the Coding Interview teaches those shapes directly.
- Work the Amazon question set. Grokking the Amazon Coding Interview covers the problems Amazon asks most.
- Learn service design, not just syntax. Amazon's architecture is the subject of its design rounds. Grokking the System Design Interview covers scaling, storage and failure handling.
- Prepare Leadership Principle stories too. Language knowledge never rescues a weak behavioral round. Start with the top behavioral questions for Amazon.
- Read the full process once. The Amazon interview guide shows every round in order.
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