A coding assessment platform is software that sets a candidate a timed programming problem in a web browser, grades the code automatically and watches for cheating. It is also called an online coding test, a hiring test or a developer screening platform. Most software engineers in India take one before their first interview. Two of the best-known coding test platforms began in Bengaluru. India needed such tests early, because its IT companies hire tens of thousands of engineering graduates every year.
The candidate receives a link and opens the test in a browser. A problem appears, for example: "Given a list of delivery times, find the longest period in which no two deliveries overlap." The candidate writes code in a language of their choice and runs it. When they submit, the platform runs the code against hidden test cases. A test case is one input together with the correct output. Some hidden cases are large, to check that the code is fast enough. The score is the share of cases passed.
Take, for example, an IT services company that recruits freshers from 40 engineering colleges in Tamil Nadu. In one week, 9,000 final-year students take the same 90-minute test, with two problems. One problem has 15 hidden test cases. A student whose code passes 12 of them in time scores 80% on that problem. The company sets a cut-off, and about 1,100 students go on to interviews. No engineer at the company had to read the 9,000 answers.
The platform must also check that the student did the test alone. Online proctoring watches through the webcam, records when the candidate switches to another browser tab, and flags a second face in the frame. The platform also compares every answer with every other answer, to find copied code.
The newest problem is AI. An AI coding assistant can solve most standard test problems in seconds. So the platforms now look for signs that an AI model wrote the answer. For example, a whole function may be pasted at once, instead of typed and corrected. Some employers go the other way. They allow the AI tool, and test what the candidate does with its answer. Others move the test into a live conversation on a technical interview platform.
The test invitation usually comes from the employer's applicant tracking system, and the scores go back into it. Students often practise on hackathon platforms first, or prepare at a coding bootcamp.