Comparing Bundle Sizes of AWS SDK for JavaScript v2 and v3

This is a small test project to compare the bundle size of Node.js files using the new v3 and old v2 AWS SDK for JavaScript. I wanted to see the differences after reading What's new about AWS SDK for JavaScript v3? on cloudonaut.io. So I created small test files based on the example code of the blog post which was making calls to DynamoDB.

Why It's Important to Know

Knowing these numbers might definitely be interesting for people wanting to use the AWS SDK on an environment like AWS Lambda where bigger artifact size means slower startup time. Especially since AWS Lambda still only provides AWS SDK v2 as a "pre-loaded" module. It means if you want to use AWS SDK v2, you don't need to bundle it with your Lambda function. However, if you want to use AWS SDK v3, you need to bundle the SDK with your Lambda function. This has a negative impact on the artifact size as you can see below.

Results

SDK Version	Included	Minified	Bundler	Variation	File Size (pretty)	File Size
v2	❌	❌	esbuild		206 Byte	206 Byte
v2	❌	✅	esbuild		132 Byte	132 Byte
v2	✅	❌	esbuild		11 MB	11,000,000 Byte
v2	✅	✅	esbuild		5.1 MB	5,100,000 Byte
v2	❌	❌	esbuild	direct	231 Byte	231 Byte
v2	❌	✅	esbuild	direct	140 Byte	140 Byte
v2	✅	❌	esbuild	direct	640 KB	640,000 Byte
v2	✅	✅	esbuild	direct	306 KB	306,000 Byte
v2	❌	❌	esbuild	es6	1.3 KB	1,300 Byte
v2	❌	✅	esbuild	es6	701 Byte	701 Byte
v2	✅	❌	esbuild	es6	11 MB	11,000,000 Byte
v2	✅	✅	esbuild	es6	5.1 MB	5,100,000 Byte
v2	❌	❌	webpack		1.5 KB	1,500 Byte
v2	❌	✅	webpack		297 Byte	297 Byte
v2	✅	❌	webpack		7.1 MB	7,100,000 Byte
v2	✅	✅	webpack		5.7 MB	5,700,000 Byte
v2	❌	❌	webpack	direct	1.5 KB	1,500 Byte
v2	❌	✅	webpack	direct	288 Byte	288 Byte
v2	✅	❌	webpack	direct	742 KB	742,000 Byte
v2	✅	✅	webpack	direct	311 KB	311,000 Byte
v2	❌	❌	webpack	es6	2.0 KB	2,000 Byte
v2	❌	✅	webpack	es6	471 Byte	471 Byte
v2	✅	❌	webpack	es6	7.1 MB	7,100,000 Byte
v2	✅	✅	webpack	es6	5.1 MB	5,100,000 Byte
v3	❌	❌	esbuild		1.3 KB	1,300 Byte
v3	❌	✅	esbuild		690 Byte	690 Byte
v3	✅	❌	esbuild		935 KB	935,000 Byte
v3	✅	✅	esbuild		435 KB	435,000 Byte
v3	❌	❌	esbuild	send	1.4 KB	1,400 Byte
v3	❌	✅	esbuild	send	720 Byte	720 Byte
v3	✅	❌	esbuild	send	936 KB	936,000 Byte
v3	✅	✅	esbuild	send	435 KB	435,000 Byte
v3	❌	❌	webpack		547 Byte	547 Byte
v3	❌	✅	webpack		206 Byte	206 Byte
v3	✅	❌	webpack		1.4 MB	1,400,000 Byte
v3	✅	✅	webpack		350 KB	350,000 Byte
v3	❌	❌	webpack	send	586 Byte	586 Byte
v3	❌	✅	webpack	send	246 Byte	246 Byte
v3	✅	❌	webpack	send	1.3 MB	1,300,000 Byte
v3	✅	✅	webpack	send	131 KB	131,000 Byte

Glossary

For generating the results, I have used different options of esbuild and webpack:

• Included means whether the AWS SDK is included in the output file,
• Minified means whether the output file is minified.

There are also a few code variations:

• a normal one, see sdk-v2/index.js and sdk-v3/index.js,
• direct is referencing the DynamoDB client directly in the code using require('aws-sdk/clients/dynamodb'), see sdk-v2/index_direct.js,
• es6 is using ES6 syntax, see sdk-v2/index_es6.js,
• send is using dynamodb.send(<new command>) for AWS SDK v3, see sdk-v3/index_send.js.

See the run.sh script for details and try reproducing them on your machine :)

Interpretation

1. If you don't include the AWS SDK v2 and you minify it, the resulting artifact has the smallest size.

2. In case you need to bundle the AWS SDK with your code, then better choose AWS SDK v3 because it results in much smaller artifact sizes. In this case it's a factor of 11x smaller - this is quite a difference!

3. There's no consistent winner between esbuild and webpack about which tool is producing the smallest artifact. Often it's just a difference of a few KB. However, it looks like webpack can better handle external dependencies with AWS SDK v2 but esbuild is better in doing that with AWS SDK v3.

Questions?

Feel free to reach out via Twitter or visit my website - I'm a Freelance Software Engineer focusing on serverless cloud projects.