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"Since ESP8266 is very limited in RAM, it cannot handle the HTTP POST data that over around 1 KB."This sounds solvable. I didn't like the size and feature matrix of nodemcu-httpdserver, so I wrote a very tiny httpd server for nodemcu too: it is less than 4KB in a single file, leaving over 31KB free according to node.heap() (and there's also removable websocket support). I also reused and tweaked the cool ide from the ESPAsyncWebServer project. I can POST over 500KB of data with no problems in a multipart form request: after finding the start boundary the callback function receives all the data continuously in chunks of about 1,5KB stopping at Content-Length bytes. I tested the upload with chrome and firefox. Here's my approach:https://github.com/harrytuttle/nodemcu-httpd/