WiFiManager
WiFi Connection manager with web captive portal
...The configuration portal is of the captive variety, so on various devices it will present the configuration dialogue as soon as you connect to the created access point. When your ESP starts up, it sets it up in Station mode and tries to connect to a previously saved Access Point. If this is unsuccessful (or no previous network saved) it moves the ESP into Access Point mode and spins up a DNS and WebServer (default ip 192.168.4.1). Using any wifi enabled device with a browser (computer, phone, tablet) connect to the newly created Access Point. ...