What runtimes are supported by AWS Lambda?

Difficulty: 5/10

runtime support, custom runtimes, container images

AWS Lambda supports a variety of runtimes that allow developers to write functions in multiple programming languages. These runtimes are managed by AWS, meaning updates, patches, and environment management are handled for you. You can also bring your own runtime using custom runtime support.

Officially Supported AWS Lambda Runtimes (as of 2025)

1
Node.js (v20, v18, v16)
2
Python (v3.12, v3.11, v3.10, v3.9)
3
Java (Corretto 21, 17, 11, 8)
4
Go (v1.x)
5
Ruby (v3.2, v2.7)
6
C#/.NET (Core 6, Core 7, .NET 8)
7

Sample Custom Runtime Bootstrap (bash)

Scenario Questions

0-2 years experience

2-5 years experience

1Your team upgraded a Lambda from Node.js 12 to Node.js 18 and now sees higher cold‑start latency. How would you investigate and reduce it?

Follow-up Questions