Taking attendance in college classes usually wastes lecture time or requires costly hardware like fingerprint readers, RFID cards, or Bluetooth beacons. Simple web forms are cheaper, but students can easily share access links or class codes with absent friends who punch in from outside the room. This paper presents a practical, low-cost attendance system that needs no extra hardware or paid server hosting. The teacher’s mobile phone serves as the location anchor. When an attendance session opens, the app records the teacher’s GPS coordinates. Students then open the web portal on their own phones, select their name, type in a temporary 6-digit code shown on the board, and fetch their device location. The system calculates the distance between the student and the teacher using the standard Haversine formula. If the student is within a preset boundary (such as 35 to 50 meters), the punch is recorded as present. We tested the system with a class of 78 engineering students in a multi-story concrete college building in Kerala. The test verified 98.7% of in-class submissions accurately while blocking students outside the boundary. The app also prevents duplicate submissions from the same phone, giving colleges an easy, free way to run quick roll calls.