Converting Yaml cloudformation template to Json

AWS Console can help you with that. Open your CloudFormation template in template designer.

CloudFormation > Select your stack > Template > View in designer

You can then easily convert your template by choosing your template language as Json.

In case you wanted a command-line solution for converting from JSON to YAML and vice versa, consider the aws-cfn-template-flip project.

Install the library:

▶ pip install cfn_flip

Usage:

▶ cfn-flip 
Usage: cfn-flip [OPTIONS] [INPUT] [OUTPUT]

  AWS CloudFormation Template Flip is a tool that converts AWS
  CloudFormation templates between JSON and YAML formats, making use of the
  YAML format's short function syntax where possible.

Options:
  -i, --input [json|yaml]   Specify the input format. Overrides -j and -y
                            flags.
  -o, --output [json|yaml]  Specify the output format. Overrides -j, -y, and
                            -n flags.
  -j, --json                Convert to JSON. Assume the input is YAML.
  -y, --yaml                Convert to YAML. Assume the input is JSON.
  -c, --clean               Performs some opinionated cleanup on your
                            template.
  -l, --long                Use long-form syntax for functions when converting
                            to YAML.
  -n, --no-flip             Perform other operations but do not flip the
                            output format.
  --version                 Show the version and exit.
  --help                    Show this message and exit.

And if you have your CloudFormation template in a YAML then you can flip it to JSON using:

▶ cfn-flip -j cloudformation.yml | jq . > cloudformation.json

Use of the JQ there is optional, just to clean the formatting.

I use this and it works like a charm: https://cfnflip.com/

You can convert JSON to YAML and YAML to JSON.

Copy/Paste either, will detect and flip. Opensource and Source Code available if you want to set this up as your own internal too. (no, this is NOT mine nor sponsored).

This is not just a normal Flipping tool, this works specifically with CloudFormation in mind.