India's state-run railways have received more than 20 million applicants for about 100,000 jobs, a railway ministry official has said.
The number of applicants is expected to rise further as the deadline for applications will end on Saturday, the official told Press Trust of India.
Online tests will be held for jobs in the railway police, locomotive drivers and technicians in 15 languages.
Unemployment is a huge challenge in India where millions are out of work.
Officials said they were overwhelmed by the response to the medium and low-level jobs.
"A lot of applicants are overqualified, and even PhD holders are applying for the technicians job," a railway official was quoted by the Economic Times newspaper as saying.
The Press Trust of India news agency reported that more than five million people had applied online for the positions of technicians and locomotive drivers alone.
India has one of the largest railway networks in the world, used by around 23 million passengers daily. Built mostly under British colonial rule, the railway network is the backbone of public transport.
With more than a million workers, India's railways is also one of the world's largest employers.
Government recruitment drives have attracted massive responses in other parts of India, too.
In 2015, authorities in India's most populous state Uttar Pradesh received 2.3 million applications for 368 low-level government jobs.
During the same year, several people were injured in a stampede when thousands turned up to join the Indian army in the southern city of Visakhapatnam.
In 2010, one man was killed and 11 others were injured in the crush when more than 10,000 candidates gathered to join the police in Mumbai.
In 1999, the government in West Bengal state was deluged with responses when they advertised 281 jobs and received nearly one million applications.