I don't know why these programmers don't have a button. But you need to solder a button to connect one of the pins to ground before you can flash the esp01. Luckily I had something in my spares basket. I didn't read the description carefully so I had trouble flashing before I went back and read the review and problem description. You need to change it as soon as you receive it. I would deduct more stars but I think it's a design issue with programmers like this.
π Ximimark 1Pcs ESP8266 Network Relay WIFI Module 220V 10A DC 7-30V 4 Layers Board TVS Input Automatic Protection: Enhanced Home Automation Solution
8 Review
MikroTik S+RJ10 Ethernet Transceiver
10 Review
TRENDnet TC-TP1 Network Signal Testing Probe with Adjustable Volume, Speaker and Compatibility for TC-NT2
8 Review
π SFP Copper RJ45 Transceiver Gigabit Module 1000Base-T Compatible: Cisco GLC-T/SFP-GE-T, Meraki MA-SFP-1GB-TX, Mikrotik, Ubiquiti, Netgear, D-Link, TP-Link, Broadcom - 100 Reach, 2 Pack
8 Review
π CERRXIAN RS232 to Ethernet Serial Device Server - TCP/IP Converter with 1Port DB9 RS232 Serial to Ethernet Connectivity
3 Review
π StarTech.com NETRS2321P: 1-Port RS232 to Ethernet IP Converter, Serial over IP Device Server - Black
5 Review
UGREEN USB 3.0 Ethernet Adapter Hub with RJ45: Fast Gigabit Ethernet Converter, 3 Ports USB 3.0 Hub Compatible for MacBook, iMac, Surface Pro, Chromebook, Laptop, PC
11 Review
π USR-TCP232-410s: RS232/RS485 Serial to Ethernet Adapter/IP Device Server with DHCP/DNS Support
4 Review