Currently google-swiffy can only convert .swf files under 1MB. The file I have in mind is 3.2MB. Thank you.
https://github.com/blvz/swiffy-convert
I am using this with nodeJS. I feel that it's still using online server to convert swf, but it somehow can convert swf file bigger than 1MB. Probably the file size limit is in client side. I am not sure.
There also is a benefit that, by adding some script I can convert tons of swf in one click
PS I feel that if your swf is really too big, the server still block our request