Uploading file to serverless

If I want to upload a file to serverless, then what is the way to do this? Somewhere I saw to use intermediate base64 representation. Setting aside the latency issues for encoding and decoding, what if my file is very large? I have to convert to base64 and then append a very large string to my request, which is not very neat. Also as the file grows larger, we would send large strings, is there any throughput loss compared to multidata-format upload?