WiFiClient client = server.available();
      client.setNoDelay(1);
      // stuff...
      client.println("HTTP/1.1 200 OK");
      client.println("Content-Type: image/bmp");
      client.println("Content-Length: 307254");
      client.println();
      webFile = SPIFFS.open("/2016b.BMP", "r");

      if (webFile) {
        const int bufSize = 1760; 
        byte clientBuf[bufSize];
        int clientCount = 0;
        prevTime=millis();

        while (webFile.available())
        {
          clientBuf[clientCount] = webFile.read();
          clientCount++;

          if (clientCount > bufSize-1)
          {          
            client.write((const uint8_t *)clientBuf, bufSize);
            clientCount = 0;
          }
        }
        // final < bufSize byte cleanup packet
        if (clientCount > 0) client.write((const uint8_t *)clientBuf, clientCount);

        // close the file:
        webFile.close();
      } else {
        Serial.println("file !fnd");
      }

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
//#include <SD.h>
#include <SPI.h>
#include "FS.h"

const char* ssid     = "linksys"; //change it
const char* password = "******";
File webFile;
char servername[] = "192.168.1.100"; //change it
WiFiClient client;

unsigned long laikas;

void setup() {
  Serial.begin(230400);
  // We start by connecting to a WiFi network
 SPIFFS.begin();
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("WiFi connected,");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
  // print the received signal strength:
  long rssi = WiFi.RSSI();
  Serial.print("signal strength (RSSI):");
  Serial.println(rssi); 

  laikas = millis();
  webFile = SPIFFS.open("/u1.png", "r"); //change it

  //webFile.close();
  laikas = millis() - laikas;
  //prints time since program started
  Serial.println(laikas);
  laikas = millis();
  //SIUNTIMAS HTTTP
    if (client.connect(servername, 80)) {
      client.setNoDelay(true);
      Serial.println("Connected to Server");

      laikas = millis();
      // Make a HTTP request:
      client.println("POST /~Carre/errtest.php?azyx=1&d=1 HTTP/1.1");
      client.println("Host: 192.168.1.1"); //change it
      client.println("Connection: close");
      //client.println("Cache-Control: max-age=0");
      client.println("Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryjg2qVIUS8teOAbN3");
      client.println("Content-Length: 1048772"); //file size  //change it
      client.println();
      client.println("------WebKitFormBoundaryjg2qVIUS8teOAbN3");
      client.println("Content-Disposition: form-data; name=\"FileGDF\"; filename=\"pic.png\""); //change it
      client.println("Content-Type: application/octet-stream");
      client.println();
      client.write(webFile);
      client.println(); //file end

      client.println("------WebKitFormBoundaryjg2qVIUS8teOAbN3--");
      client.println();
      webFile.close();
      Serial.println("done");}
  laikas = millis() - laikas;
  //prints time since sending started
  Serial.println(laikas);
  if(!eRcv());
  client.stop();
  SPIFFS.end();
}

void loop() {
}

byte eRcv()
{
  byte respCode;
  byte thisByte;
  while(!client.available()) delay(1);
  respCode = client.peek();
  while(client.available())
  {  
    thisByte = client.read();    
    Serial.write(thisByte);
  }
  return 1;
}

<?php
$target_dir = "uploads/";
$filename = basename(@$_FILES["FileGDF"]["name"]);
$target_file = $target_dir . $filename;
$uploadOk = 0;
$FileType = pathinfo($target_file,PATHINFO_EXTENSION);

if(isset($_GET["azyx"])&&(isset($_GET["d"]))) {
  if (file_exists($target_file)) {
    if (file_put_contents($target_file,file_get_contents(@$_FILES["FileGDF"]["tmp_name"]))){
      echo "The file ". $filename. " has been uploaded.<br />";
      $uploadOk = $uploadOk + 1;
    } else {
      echo "Sorry, there was an error uploading your file.<br />";
    }
  }else{
    if (move_uploaded_file(@$_FILES["FileGDF"]["tmp_name"], $target_file)) {
      echo "The file ". basename($filename). " has been uploaded.<br />";
      $uploadOk = $uploadOk + 1;
    } else {
      echo "Sorry, there was an error uploading your file.<br />";
    }
  }
}
?>

 #include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <SD.h>
#include <SPI.h>
//#include "FS.h"

//const char* ssid     = "linksys";
//const char* password = "*******";

File webFile;
char servername[] = "192.168.1.1";
WiFiClient client;

unsigned long laikas;


#define MTU_Size    2*1460  // this size seems to work best

// file sending from SD card
byte clientBuf[MTU_Size];
int clientCount = 0;
int progresas = 0;
int zenklas   = 0;
int zenklas2   = 0;

// change fileName to your file (8.3 format!)
char fileName[13] = "pic.png";

void setup() {
  Serial.begin(230400);
  // We start by connecting to a WiFi network

  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.print("WiFi connected,");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
  // print the received signal strength:
  long rssi = WiFi.RSSI();
  Serial.print("signal strength (RSSI):");
  Serial.println(rssi); 
  if(SD.begin(SS,50000000) == 0){    // clk 50MHz
    Serial.println(F("SD init fail"));          
  }else{
    Serial.println(F("SD init success"));   
  }
/** part of timing only to check how long to read file takes  */
  laikas = millis();

  webFile = SD.open(fileName,FILE_READ);
  while(webFile.available())
  {
    if (webFile.available()>= MTU_Size){
      clientCount = MTU_Size;
      webFile.read(&clientBuf[0],clientCount);
    }else{
      clientCount = webFile.available();
      webFile.read(&clientBuf[0],clientCount);
    }
    if(clientCount > 0)
    {
      //client.write((const uint8_t *)&clientBuf[0],MTU_Size);
      clientCount = 0;
    }
  }
  webFile.close();
  laikas = millis() - laikas;
  //prints time since program started
  Serial.println(laikas);
/** END of read file test time   */

  laikas = millis();
  webFile = SD.open(fileName,FILE_READ);
  //SIUNTIMAS (POST) HTTTP
    if (client.connect(servername, 80)) {
      client.setNoDelay(true);
      Serial.println("Connected to Server");

      laikas = millis();
      // Make a HTTP request:

      client.println("POST /~Carre/errtest.php?azyx=1&d=1 HTTP/1.1");
      client.println("Host: 192.168.1.1");
      client.println("Connection: close");
      client.println("Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryjg2qVIUS8teOAbN3");
      client.print("Content-Length: ");client.println(webFile.size()+196);  //+196 is owerhead form boundary tags
      client.println();
      client.println("------WebKitFormBoundaryjg2qVIUS8teOAbN3");
      client.println("Content-Disposition: form-data; name=\"FileGDF\"; filename=\"pic.png\"");
      client.println("Content-Type: application/octet-stream");
      client.println();
      //Serial.println(F("Writing"));
  progresas = 0;   
  while(webFile.available())
  {
    if (webFile.available()>= MTU_Size){
      clientCount = MTU_Size;
      webFile.read(&clientBuf[0],clientCount);
    }else{
      clientCount = webFile.available();
      webFile.read(&clientBuf[0],clientCount);
    }
    if(clientCount > 0)
    {
      client.write((const uint8_t *)&clientBuf[0],clientCount);
      progresas += clientCount;
      clientCount = 0;
      // some kind of progress output
      zenklas = (progresas * 100)/webFile.size();
      if (zenklas != zenklas2){
        zenklas2 = zenklas;
        Serial.print(".");
      }
      // end of progress output
    }
  }
  client.println();//file end

/** if another field required it can be started here **/
//      client.println("------WebKitFormBoundaryjg2qVIUS8teOAbN3");
//      client.println("Content-Disposition: form-data; name=\"okey\"");
//      client.println();
//      client.println("SEND");
      client.println("------WebKitFormBoundaryjg2qVIUS8teOAbN3--"); //form end
      client.println();
      webFile.close();
      Serial.println("done");
    }
  laikas = millis() - laikas;
  //prints time since program started
  Serial.println(laikas);
  if(!eRcv());
  client.stop();
}

void loop() {
}

byte eRcv()
{
  byte respCode;
  byte thisByte;

  while(!client.available()) delay(1);
  respCode = client.peek();
  while(client.available())
  {  
    thisByte = client.read();    
    Serial.write(thisByte);
  }
  return 1;
}

[const char largeFile[] PROGMEM ={ 0xff,0x7f,0xff,0x7f,0xff,0x7f,0xff,0x7f,0xff,0x7f,0x01
,0x50,0x75,0x41,0xae,0x4e,0xa9,0x42,0x97,0x4d ..... (around 150KB in size....)

#define MTU_SIZE 2*1460
      for (int i=0; i<150000; i=i+MTU_SIZE) client.write(&largeFile[i],MTU_SIZE);   
      client.println();]

SPIFFS.begin();
File spiFile = SPIFFS.open("/big.bin", "r");
if (!spiFile) USE_SERIAL.println("file open failed");
else             USE_SERIAL.println("wav file opened");
client.write(spiFile);  //but I need to cast this to get it to work client.write((char)spiFile) and I'm not sure it's working?
spiFile.close();

In file included from C:\Users\Administrator\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\ESP8266WiFi\src/ESP8266WiFi.h:39:0,

                 from C:\Users\Administrator\Documents\arduino\POST-example\POST-example.ino:1:

C:\Users\Administrator\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\ESP8266WiFi\src/WiFiClient.h: In instantiation of 'size_t WiFiClient::write(T&, size_t) [with T = unsigned char [1460]; size_t = unsigned int]':

C:\Users\Administrator\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\ESP8266WiFi\src/WiFiClient.h:84:55:   required from 'size_t WiFiClient::write(T&) [with T = fs::File; size_t = unsigned int]'

C:\Users\Administrator\Documents\arduino\POST-example\POST-example.ino:63:27:   required from here

C:\Users\Administrator\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\ESP8266WiFi\src/WiFiClient.h:123:36: error: request for member 'available' in 'source', which is of non-class type 'unsigned char [1460]'

     size_t left = source.available();

                                    ^

C:\Users\Administrator\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\libraries\ESP8266WiFi\src/WiFiClient.h:127:5: error: request for member 'read' in 'source', which is of non-class type 'unsigned char [1460]'

     source.read(buffer.get(), will_send);

     ^

exit status 1
Error compiling for board NodeMCU 1.0 (ESP-12E Module).

#include "FS.h"
#include "WiFiClient.h"
#include <ESP8266WiFi.h>

const char *ssidAP = "ESP";
const char *passwordAP = "12345678";
String http_header = ("HTTP/1.1 200 OK\r\n"
                  "Content-Type: text/html\r\n"
                  "\r\n"
                  "<!DOCTYPE HTML>\r\n"
                  "<html>\r\n"
                  "<!DOCTYPE html>\n"
                  "<html>\n");
WiFiServer server(80);
WiFiClient client;

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_AP);
  WiFi.softAP(ssidAP, passwordAP);
  IPAddress myIP = WiFi.softAPIP();
  Serial.print("AP IP address: ");
  Serial.println(myIP);
  server.begin();
  SPIFFS.begin();
}
void loop() {
  client = server.available();
  if (!client) {
    Serial.println("I'm in loop");
    delay(1000);
    return;
     }
 
  File  webFile = SPIFFS.open("/YourFile.html", "r"); // I use html file because .html and .txt has the simplest header
  client.println(http_header);
  client.write(webFile);
  webFile.close();
}

#include "Arduino.h"
#include <ESP8266WiFi.h>
#include <FS.h>

WiFiServer server(80);
WiFiClient client;

void setup()
{
  WiFi.mode(WIFI_AP);
  WiFi.softAP("Hello-World");

  //start UART and the server
  Serial.begin(74880);

  server.begin();
  server.setNoDelay(true);

  //Mount file system
  SPIFFS.begin();
}

void loop()
{
  client = server.available();
  if (!client)
  {
    Serial.println("I'm in loop");
    delay(1000);
    return;
  }

  File webFile = SPIFFS.open("/test.gif", "r");

  client.println("HTTP/1.1 200 OK");
  client.println("Connection: close");
  client.println("Content-Type: image/gif");
  client.println("Content-Length: " + String((webFile.size())));
  client.println();

  client.write(webFile);
  webFile.close();
}

/* SearchSPIFFS.ino 6 May 2017
   SPIFFS plain text file has 100 lines, each line approx 1kb
   After reading 30 lines (30kb) in less than 2 seconds it takes several seconds PER line
 */
#include "FS.h"

String line;
unsigned int lineNumber;
unsigned int line2Find = 32;
File MyFile = SPIFFS.open("SomeData.txt", "r");

void test(){
      while(MyFile.available()) {   // we could open the file, so loop through it to find the record we require
        lineNumber++;        
        Serial.println(lineNumber);          // show line number of SPIFFS file
        line = MyFile.readStringUntil('\n'); // Read line by line from the file
        if(lineNumber == line2Find){        
          Serial.println(F("Found record"));                             
          break;                             // exit while loop once record is found
        }
      }   
}

void setup() {
  Serial.begin(115200);
  Serial.println(F("\nStarted"));
  test();                                    // find line 32 of plain text SPIFFS file
}

void loop() {
  yield();
}

  String File_name = dir.fileName();
  Serial.print("File_name : ");
  Serial.println(File_name);
  file = SPIFFS.open(File_name, "r");
  client.println(Link);
  client.print("Host: ");
  client.println(host);
  client.println("Connection: close");
  client.println("Content-Type : application/x-www-form-urlencoded");

  client.println("Content-Length: 124354");
  Serial.println(file.size());
  client.println();
  client.write("Large_data=");   // Variable Name
  client.write(file);     // Send file 
}