What is the max payload for a REST post request to AWS lamda?
This question is essentially this question, but for AWS Lambda HTTP events.
Also does AWS Gateway add any restriction of payload size?
Lambda has a strict payload limit size of 6MB. If you want to upload more than 6MB you can do like this,
Lambda (Create S3 Signed URL) --> Upload to S3 --> Trigger from S3 to lambda --> Process in lambda
Lambda Limits:
https://docs.aws.amazon.com/lambda/latest/dg/limits.html
API Gateway Limits:
https://docs.aws.amazon.com/apigateway/latest/developerguide/limits.html
Hope it helps.