here is the question, is there any limit in HTTP headers? The Answer is No.
there is no limit but web-servers are limiting their incoming request header size even in POST requests therefore we getting 413 (Request header is too large). This limitation is including request line and header fields.
http://httpd.apache.org/docs/2.2/mod/core.html#limitrequestfieldsize
https://tomcat.apache.org/tomcat-5.5-doc/config/http.html
http://nginx.org/en/docs/http/ngx_http_core_module.html#large_client_header_buffers
Maximum on http header values?
In my case, I had SpringBoot 1.5.8 and used HTTP POST, however I had to add:
server.max-http-header-size=10000000
in application.properties.